Building an integrated neurodegenerative disease database at an academic health center

Seizures exacerbate excitatory: inhibitory imbalance in Alzheimer's disease and 5XFAD mice

Approximately 22% of Alzheimer's disease (AD) patients suffer from seizures, and the co-occurrence of seizures and epileptiform activity exacerbates AD pathology and related cognitive deficits, suggesting that seizures may be a targetable component of AD progression. Given that alterations in neuronal excitatory:inhibitory (E:I) balance occur in epilepsy, we hypothesized that decreased markers of inhibition relative to those of excitation would be present in AD patients. We similarly hypothesized that in 5XFAD mice, the E:I imbalance would progress from an early stage (prodromal) to later symptomatic stages and be further exacerbated by pentylenetetrazol (PTZ) kindling. Post-mortem AD temporal cortical tissues from patients with or without seizure history were examined for changes in several markers of E:I balance, including levels of the inhibitory GABAA receptor, the sodium potassium chloride cotransporter 1 (NKCC1) and potassium chloride cotransporter 2 (KCC2) and the excitatory NMDA and AMPA type glutamate receptors. We performed patch-clamp electrophysiological recordings from CA1 neurons in hippocampal slices and examined the same markers of E:I balance in prodromal 5XFAD mice. We next examined 5XFAD mice at chronic stages, after PTZ or control protocols, and in response to chronic mTORC1 inhibitor rapamycin, administered following kindled seizures, for markers of E:I balance. We found that AD patients with comorbid seizures had worsened cognitive and functional scores and decreased GABAA receptor subunit expression, as well as increased NKCC1/KCC2 ratios, indicative of depolarizing GABA responses. Patch clamp recordings of prodromal 5XFAD CA1 neurons showed increased intrinsic excitability, along with decreased GABAergic inhibitory transmission and altered glutamatergic neurotransmission, indicating that E:I imbalance may occur in early disease stages. Furthermore, seizure induction in prodromal 5XFAD mice led to later dysregulation of NKCC1/KCC2 and a reduction in GluA2 AMPA glutamate receptor subunit expression, indicative of depolarizing GABA receptors and calcium permeable AMPA receptors. Finally, we found that chronic treatment with the mTORC1 inhibitor, rapamycin, at doses we have previously shown to attenuate seizure-induced amyloid-β pathology and cognitive deficits, could also reverse elevations of the NKCC1/KCC2 ratio in these mice. Our data demonstrate novel mechanisms of interaction between AD and epilepsy and indicate that targeting E:I balance, potentially with US Food and Drug Administration-approved mTOR inhibitors, hold therapeutic promise for AD patients with a seizure history.

Pathologic and cognitive correlates of plasma biomarkers in neurodegenerative disease

INTRODUCTION

We investigate pathological correlates of plasma phosphorylated tau 181 (p-tau181), glial fibrillary acidic protein (GFAP), and neurofilament light chain (NfL) across a clinically diverse spectrum of neurodegenerative disease, including normal cognition (NormCog) and impaired cognition (ImpCog).

METHODS

Participants were NormCog (n = 132) and ImpCog (n = 461), with confirmed β-amyloid (Aβ+/-) status (cerebrospinal fluid, positron emission tomography, autopsy) and single molecule array plasma measurements. Logistic regression and receiver operating characteristic (ROC) area under the curve (AUC) tested how combining plasma analytes discriminated Aβ+ from Aβ-. Survival analyses tested time to clinical dementia rating (global CDR) progression.

RESULTS

Multivariable models (p-tau+GFAP+NfL) had the best performance to detect Aβ+ in NormCog (ROCAUC = 0.87) and ImpCog (ROCAUC = 0.87). Survival analyses demonstrated that higher NfL best predicted faster CDR progression for both Aβ+ (hazard ratio [HR] = 2.94; p = 8.1e-06) and Aβ- individuals (HR = 3.11; p = 2.6e-09).

DISCUSSION

Combining plasma biomarkers can optimize detection of Alzheimer's disease (AD) pathology across cognitively normal and clinically diverse neurodegenerative disease.

HIGHLIGHTS

Participants were clinically heterogeneous, with autopsy- or biomarker-confirmed Aβ. Combining plasma p-tau181, GFAP, and NfL improved diagnostic accuracy for Aβ status. Diagnosis by plasma biomarkers is more accurate in amnestic AD than nonamnestic AD. Plasma analytes show independent associations with tau PET and post mortem Aβ/tau. Plasma NfL predicted longitudinal cognitive decline in both Aβ+ and Aβ- individuals.

Cytoarchitectonic gradients of laminar degeneration in behavioral variant frontotemporal dementia

Behavioral variant frontotemporal dementia (bvFTD) is a clinical syndrome primarily caused by either tau (bvFTD-tau) or TDP-43 (bvFTD-TDP) proteinopathies. We previously found lower cortical layers and dorsolateral regions accumulate greater tau than TDP-43 pathology; however, patterns of laminar neurodegeneration across diverse cytoarchitecture in bvFTD is understudied. We hypothesized that bvFTD-tau and bvFTD-TDP have distinct laminar distributions of pyramidal neurodegeneration along cortical gradients, a topologic order of cytoarchitectonic subregions based on increasing pyramidal density and laminar differentiation. Here, we tested this hypothesis in a frontal cortical gradient consisting of five cytoarchitectonic types (i.e., periallocortex, agranular mesocortex, dysgranular mesocortex, eulaminate-I isocortex, eulaminate-II isocortex) spanning anterior cingulate, paracingulate, orbitofrontal, and mid-frontal gyri in bvFTD-tau (n=27), bvFTD-TDP (n=47), and healthy controls (HC; n=32). We immunostained all tissue for total neurons (NeuN; neuronal-nuclear protein) and pyramidal neurons (SMI32; non-phosphorylated neurofilament) and digitally quantified NeuN-immunoreactivity (ir) and SMI32-ir in supragranular II-III, infragranular V-VI, and all I-VI layers in each cytoarchitectonic type. We used linear mixed-effects models adjusted for demographic and biologic variables to compare SMI32-ir between groups and examine relationships with the cortical gradient, long-range pathways, and clinical symptoms. We found regional and laminar distributions of SMI32-ir expected for HC, validating our measures within the cortical gradient framework. While SMI32-ir loss was not related to the cortical gradient in bvFTD-TDP, SMI32-ir progressively decreased along the cortical gradient of bvFTD-tau and included greater SMI32-ir loss in supragranular eulaminate-II isocortex in bvFTD-tau vs bvFTD-TDP ( p =0.039). In a structural model for long-range laminar connectivity between infragranular mesocortex and supragranular isocortex, we found a larger laminar ratio of mesocortex-to-isocortex SMI32-ir in bvFTD-tau vs bvFTD-TDP ( p =0.019), suggesting select long-projecting pathways may contribute to isocortical-predominant degeneration in bvFTD-tau. In cytoarchitectonic types with the highest NeuN-ir, we found lower SMI32-ir in bvFTD-tau vs bvFTD-TDP ( p =0.047), suggesting pyramidal neurodegeneration may occur earlier in bvFTD-tau. Lastly, we found that reduced SMI32-ir related to behavioral severity and frontal-mediated letter fluency, not temporal-mediated confrontation naming, demonstrating the clinical relevance and specificity of frontal pyramidal neurodegeneration to bvFTD-related symptoms. Our data suggest loss of neurofilament-rich pyramidal neurons is a clinically relevant feature of bvFTD that selectively worsens along a frontal cortical gradient in bvFTD-tau, not bvFTD-TDP. Therefore, tau-mediated degeneration may preferentially involve pyramidal-rich layers that connect more distant cytoarchitectonic types. Moreover, the hierarchical arrangement of cytoarchitecture along cortical gradients may be an important neuroanatomical framework for identifying which types of cells and pathways are differentially involved between proteinopathies.

The Effect of Gender and APOE ɛ4 Status on Brain Amyloid-β Deposition in Different Age Groups of Mild Cognitively Impaired Individuals: A PET-CT Study

BACKGROUND

Gender, APOE ɛ4 status and age have different effects on brain amyloid deposition in patients with mild cognitively impaired (MCI).

OBJECTIVE

To investigate the effect of gender×APOE ɛ4 status interaction on Aβ deposition in the brains of individuals with MCI in different age groups by PET scanning.

METHODS

204 individuals with MCI were classified into younger or older groups based on whether they were under or over 65 years of age. APOE genotyping, structural MRI, amyloid PET scans, and neuropsychological tests were performed. The effect of gender×APOE ɛ4 status interaction on Aβ deposition was assessed in different age groups.

RESULTS

APOE ɛ4 carriers had higher amyloid deposition than noncarriers in the whole group. Females with MCI had more amyloid deposition in the medial temporal lobe than males in the whole cohort and younger group. Older individuals with MCI had higher amyloid deposition than younger individuals. In stratified analysis by age, female APOE ɛ4 carriers had significantly increased amyloid deposition compared to their male counterparts only in the medial temporal lobe in the younger group. Amyloid deposition was increased in female APOE ɛ4 carriers compared to noncarriers in the younger group, whereas higher amyloid deposition was observed in male APOE ɛ4 carriers in the older group.

CONCLUSION

Women in the younger group with MCI who were APOE ɛ4 carriers had more amyloid deposition in the brain, while men in the older group with MCI who were APOE ɛ4 carriers had higher amyloid deposition.

Awareness of diagnosis predicts changes in quality of life in individuals with mild cognitive impairment and mild stage dementia

BACKGROUND AND OBJECTIVE

This observational study examined how awareness of diagnosis predicted changes in cognition and quality of life (QOL) 1 year later in older adults with normal cognition and dementia diagnoses.

RESEARCH DESIGN AND METHODS

Older adults (n = 259) with normal cognition, mild cognitive impairment (MCI), or mild stage Alzheimer's disease (AD) completed measures of diagnostic awareness, cognition, and multiple domains of QOL. We compared 1-year change in cognition and QOL by diagnostic group and diagnostic awareness.

RESULTS

Patients who were unaware of their diagnosis at baseline showed average decreases in both satisfaction with daily life (QOL-AD; paired mean difference (PMD) = -0.9, p < 0.05) and physical functioning (SF-12 PCS; PMD = -2.5, p < 0.05). In contrast, patients aware of their diagnosis at baseline showed no statistically discernable changes in most QOL domains (all p > 0.05). Of patients aware of their diagnosis at baseline (n = 111), those who were still aware (n = 84) showed a decrease in mental functioning at follow up (n = 27; SF-12 MCS). Change in MoCA scores in patients unaware of their diagnosis was similar to that in patients aware of their diagnosis, -1.4 points (95% CI -2.6 to -0.6) and -1.7 points (95% CI -2.4 to -1.1) respectively.

DISCUSSION AND IMPLICATIONS

Awareness of one's diagnosis of MCI or AD, not the severity of cognitive impairment, may predict changes in patients' mental functioning, expectations of their memory, satisfaction with daily life, and physical functioning. The findings may help clinicians anticipate the types of threats to wellbeing that a patient might encounter and identify key domains for monitoring.

Retinal photoreceptor layer thickness has disease specificity and distinguishes predicted FTLD-Tau from biomarker-determined Alzheimer's disease

While Alzheimer's disease (AD) is associated with inner retina thinning (retinal nerve fiber layer and ganglion cell layer), we have observed photoreceptor outer nuclear layer (ONL) thinning in patients with frontotemporal lobar degeneration tauopathy (FTLD-Tau) compared to normal controls. We hypothesized that ONL thinning may distinguish FTLD-Tau from patients with biomarker evidence of AD neuropathologic change (ADNC) and will correlate with FTLD-Tau disease severity. Predicted FTLD-Tau (pFTLD-Tau; n = 21; 33 eyes) and predicted ADNC (pADNC; n = 24; 46 eyes) patients were consecutively enrolled, underwent optical coherence tomography macula imaging, and disease was categorized (pFTLD-Tau vs. pADNC) with cerebrospinal fluid biomarkers, genetic testing, and autopsy data when available. Adjusting for age, sex, and race, pFTLD-Tau patients had a thinner ONL compared to pADNC, while retinal nerve fiber layer and ganglion cell layer were not significantly different. Reduced ONL thickness correlated with worse performance on Folstein Mini-Mental State Examination and clinical dementia rating plus frontotemporal dementia sum of boxes for pFTLD-Tau but not pADNC. Photoreceptor ONL thickness may serve as an important noninvasive diagnostic marker that distinguishes FTLD-Tau from AD neuropathologic change.

Digital Histological Study of Neocortical Grey and White Matter Tau Burden Across Tauopathies

3R/4R-tau species are found in Alzheimer disease (AD) and ∼50% of Lewy body dementias at autopsy (LBD+tau); 4R-tau accumulations are found in progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). Digital image analysis techniques can elucidate patterns of tau pathology more precisely than traditional methods but repeatability across centers is unclear. We calculated regional percentage areas occupied by tau pathological inclusions from the middle frontal cortex (MFC), superior temporal cortex (STC), and angular gyrus (ANG) from cases from the University of Pennsylvania and the University of California San Diego with AD, LBD+tau, PSP, or CBD (n = 150) using QuPath. In both cohorts, AD and LBD+tau had the highest grey and white matter tau burden in the STC (p ≤ 0.04). White matter tau burden was relatively higher in 4R-tauopathies than 3R/4R-tauopathies (p < 0.003). Grey and white matter tau were correlated in all diseases (R2=0.43-0.79, p < 0.04) with the greatest increase of white matter per unit grey matter tau observed in PSP (p < 0.02 both cohorts). Grey matter tau negatively correlated with MMSE in AD and LBD+tau (r = -4.4 to -5.4, p ≤ 0.02). These data demonstrate the feasibility of cross-institutional digital histology studies that generate finely grained measurements of pathology which can be used to support biomarker development and models of disease progression.

Distinguishing Frontotemporal Lobar Degeneration Tau From TDP-43 Using Plasma Biomarkers

Importance

Biomarkers are lacking that can discriminate frontotemporal lobar degeneration (FTLD) associated with tau (FTLD-tau) or TDP-43 (FTLD-TDP).

Objective

To test whether plasma biomarkers glial fibrillary acidic protein (GFAP), neurofilament light chain (NfL), or their ratio (GFAP/NfL) differ between FTLD-tau and FTLD-TDP.

Design, Setting, and Participants

This retrospective cross-sectional study included data from 2009 to 2020 from the University of Pennsylvania Integrated Neurodegenerative Disease Database, with a median (IQR) follow-up duration of 2 (0.3-4.2) years. The training sample was composed of patients with autopsy-confirmed and familial FTLD; nonimpaired controls were included as a reference group. The independent validation sample included patients with FTD with a clinical diagnosis of progressive supranuclear palsy syndrome (PSPS) associated with tau (PSPS-tau) or amytrophic lateral sclerosis (ALS) associated with TDP-43 (ALS-TDP). In patients with FTLD with autopsy-confirmed or variant-confirmed pathology, receiver operating characteristic (ROC) curves tested the GFAP/NfL ratio and established a pathology-confirmed cut point. The cut point was validated in an independent sample of patients with clinical frontotemporal dementia (FTD). Data were analyzed from February to July 2022.

Exposures

Clinical, postmortem histopathological assessments, and plasma collection.

Main Outcomes and Measures

ROC and area under the ROC curve (AUC) with 90% CIs evaluated discrimination of pure FTLD-tau from pure FTLD-TDP using plasma GFAP/NfL ratio; the Youden index established optimal cut points. Sensitivity and specificity of cut points were assessed in an independent validation sample.

Results

Of 349 participants with available plasma data, 234 met inclusion criteria (31 controls, 141 in the training sample, and 62 in the validation sample). In the training sample, patients with FTLD-tau were older than patients with FTLD-TDP (FTLD-tau: n = 46; mean [SD] age, 65.8 [8.29] years; FTLD-TDP: n = 95; mean [SD] age, 62.3 [7.82] years; t84.6 = 2.45; mean difference, 3.57; 95% CI, 0.67-6.48; P = .02) but with similar sex distribution (FTLD-tau: 27 of 46 [59%] were male; FTLD-TDP: 51 of 95 [54%] were male; χ21 = 0.14; P = .70). In the validation sample, patients with PSPS-tau were older than those with ALS-TDP (PSPS-tau: n = 31; mean [SD] age, 69.3 [7.35] years; ALS-TDP: n = 31; mean [SD] age, 54.6 [10.17] years; t54.6 = 6.53; mean difference, 14.71; 95% CI, 10.19-19.23; P < .001) and had fewer patients who were male (PSPS-tau: 9 of 31 [29%] were male; ALS-TDP: 22 of 31 [71%] were male; χ21 = 9.3; P = .002). ROC revealed excellent discrimination of FTLD-tau from FTLD-TDP by plasma GFAP/NfL ratio (AUC = 0.89; 90% CI, 0.82-0.95; sensitivity = 0.73; 90% CI, 0.65-0.89; specificity = 0.89; 90% CI, 0.78-0.98), which was higher than either GFAP level alone (AUC = 0.65; 90% CI, 0.54-0.76) or NfL levels alone (AUC = 0.75; 90% CI, 0.64-0.85). In the validation sample, there was sensitivity of 0.84 (90% CI, 0.66-0.94) and specificity of 0.81 (90% CI, 0.62-0.91) when applying the autopsy-derived plasma GFAP/NfL threshold.

Conclusions and Relevance

The plasma ratio of GFAP/NfL may discriminate FTLD-tau from FTLD-TDP.

Neuropsychological and Neuroanatomical Features of Patients with Behavioral/Dysexecutive Variant Alzheimer’s disease (AD): A Comparison to Behavioral Variant Frontotemporal Dementia and Amnestic AD Groups

Background: An understudied variant of Alzheimer’s disease (AD), the behavioral/dysexecutive variant of AD (bvAD), is associated with progressive personality, behavior, and/or executive dysfunction and frontal atrophy. Objective: This study characterizes the neuropsychological and neuroanatomical features associated with bvAD by comparing it to behavioral variant frontotemporal dementia (bvFTD), amnestic AD (aAD), and subjects with normal cognition. Methods: Subjects included 16 bvAD, 67 bvFTD, and 18 aAD patients, and 26 healthy controls. Neuropsychological assessment and MRI data were compared between these groups. Results: Compared to bvFTD, bvAD showed more significant visuospatial impairments (Rey Figure copy and recall), more irritability (Neuropsychological Inventory), and equivalent verbal memory (Philadelphia Verbal Learning Test). Compared to aAD, bvAD indicated more executive dysfunction (F-letter fluency) and better visuospatial performance. Neuroimaging analysis found that bvAD showed cortical thinning relative to bvFTD posteriorly in left temporal-occipital regions; bvFTD had cortical thinning relative to bvAD in left inferior frontal cortex. bvAD had cortical thinning relative to aAD in prefrontal and anterior temporal regions. All patient groups had lower volumes than controls in both anterior and posterior hippocampus. However, bvAD patients had higher average volume than aAD patients in posterior hippocampus and higher volume than bvFTD patients in anterior hippocampus after adjustment for age and intracranial volume. Conclusion: Findings demonstrated that underlying pathology mediates disease presentation in bvAD and bvFTD.

Ex vivo MRI and histopathology detect novel iron-rich cortical inflammation in frontotemporal lobar degeneration with tau versus TDP-43 pathology

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Comparative study of whole-hemisphere ex vivo T2*-weighted MRI and histopathology.

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Sample of FTLD-Tau and FTLD-TDP subtypes with reference to healthy and AD brain.

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Novel focal upper cortical-layer iron-rich pathology distinguishes FTLD-TDP from clinically-similar FTLD-Tau and AD.

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Distinct novel iron-rich FTLD-Tau pathology in mid-to-deep cortical-layers and WM.

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T2*-weighted MRI signatures offer in vivo biomarker targets for FTLD proteinopathy.

Frontotemporal lobar degeneration (FTLD) is a heterogeneous spectrum of age-associated neurodegenerative diseases that include two main pathologic categories of tau (FTLD-Tau) and TDP-43 (FTLD-TDP) proteinopathies. These distinct proteinopathies are often clinically indistinguishable during life, posing a major obstacle for diagnosis and emerging therapeutic trials tailored to disease-specific mechanisms. Moreover, MRI-derived measures have had limited success to date discriminating between FTLD-Tau or FTLD-TDP. T₂*-weighted (T2*w) ex vivo MRI has previously been shown to be sensitive to non-heme iron in healthy intracortical lamination and myelin, and to pathological iron deposits in amyloid-beta plaques and activated microglia in Alzheimer’s disease neuropathologic change (ADNC). However, an integrated, ex vivo MRI and histopathology approach is understudied in FTLD. We apply joint, whole-hemisphere ex vivo MRI at 7 T and histopathology to the study autopsy-confirmed FTLD-Tau (n = 4) and FTLD-TDP (n = 3), relative to ADNC disease-control brains with antemortem clinical symptoms of frontotemporal dementia (n = 2), and an age-matched healthy control. We detect distinct laminar patterns of novel iron-laden glial pathology in both FTLD-Tau and FTLD-TDP brains. We find iron-positive ameboid and hypertrophic microglia and astrocytes largely in deeper GM and adjacent WM in FTLD-Tau. In contrast, FTLD-TDP presents prominent superficial cortical layer iron reactivity in astrocytic processes enveloping small blood vessels with limited involvement of adjacent WM, as well as more diffuse distribution of punctate iron-rich dystrophic microglial processes across all GM lamina. This integrated MRI/histopathology approach reveals ex vivo MRI features that are consistent with these pathological observations distinguishing FTLD-Tau and FTLD-TDP subtypes, including prominent irregular hypointense signal in deeper cortex in FTLD-Tau whereas FTLD-TDP showed upper cortical layer hypointense bands and diffuse cortical speckling. Moreover, differences in adjacent WM degeneration and iron-rich gliosis on histology between FTLD-Tau and FTLD-TDP were also readily apparent on MRI as hyperintense signal and irregular areas of hypointensity, respectively that were more prominent in FTLD-Tau compared to FTLD-TDP. These unique histopathological and radiographic features were distinct from healthy control and ADNC brains, suggesting that iron-sensitive T2*w MRI, adapted to in vivo application at sufficient resolution, may eventually offer an opportunity to improve antemortem diagnosis of FTLD proteinopathies using tissue-validated methods.

Signature laminar distributions of pathology in frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD) with either tau (FTLD-tau) or TDP-43 (FTLD-TDP) inclusions are distinct proteinopathies that frequently cause similar frontotemporal dementia (FTD) clinical syndromes. FTD syndromes often display macroscopic signatures of neurodegeneration at the level of regions and networks, but it is unclear if subregional laminar pathology display patterns unique to proteinopathy or clinical syndrome. We hypothesized that FTLD-tau and FTLD-TDP accumulate pathology in relatively distinct cortical layers independent of clinical syndrome, with greater involvement of lower layers in FTLD-tau. The current study examined 170 patients with either FTLD-tau (n = 73) or FTLD-TDP (n = 97) spanning dementia and motor phenotypes in the FTD spectrum. We digitally measured the percent area occupied by tau and TDP-43 pathology in upper layers (I-III), lower layers (IV-VI), and juxtacortical white matter (WM) from isocortical regions in both hemispheres where available. Linear mixed-effects models compared ratios of upper to lower layer pathology between FTLD groups and investigated relationships with regions, WM pathology, and global cognitive impairment while adjusting for demographics. We found lower ratios of layer pathology in FTLD-tau and higher ratios of layer pathology in FTLD-TDP, reflecting lower layer-predominant tau pathology and upper layer-predominant TDP-43 pathology, respectively (p < 0.001). FTLD-tau displayed lower ratios of layer pathology related to greater WM tau pathology (p = 0.002) and to earlier involved/severe pathology regions (p = 0.007). In contrast, FTLD-TDP displayed higher ratios of layer pathology not related to either WM pathology or regional severity. Greater cognitive impairment was associated with higher ratios of layer pathology in FTLD-tau (p = 0.018), but was not related to ratios of layer pathology in FTLD-TDP. Lower layer-predominant tau pathology and upper layer-predominant TDP-43 pathology are proteinopathy-specific, regardless of clinical syndromes or regional networks that define these syndromes. Thus, patterns of laminar change may provide a useful anatomical framework for investigating how degeneration of select cells and corresponding laminar circuits influence large-scale networks and clinical symptomology in FTLD.

Self- and Partner-Reported Subjective Memory Complaints: Association with Objective Cognitive Impairment and Risk of Decline

Background

Episodic memory decline is a hallmark of Alzheimer's disease (AD). Subjective memory complaints (SMCs) may represent one of the earliest signs of impending cognitive decline. The degree to which self- or partner-reported SMCs predict cognitive change remains unclear.

Objective

We aimed to evaluate the relationship between self- and partner-reported SMCs, objective cognitive performance, AD biomarkers, and risk of future decline in a well-characterized longitudinal memory center cohort. We also evaluated whether study partner characteristics influence reports of SMCs.

Methods

758 participants and 690 study partners were recruited from the Penn Alzheimer's Disease Research Center Clinical Core. Participants included those with Normal Cognition, Mild Cognitive Impairment, and AD. SMCs were measured using the Prospective and Retrospective Memory Questionnaire (PRMQ), and were evaluated for their association with cognition, genetic, plasma, and neuroimaging biomarkers of AD, cognitive and functional decline, and diagnostic progression over an average of four years.

Results

We found that partner-reported SMCs were more consistent with cognitive test performance and increasing symptom severity than self-reported SMCs. Partner-reported SMCs showed stronger correlations with AD-associated brain atrophy, plasma biomarkers of neurodegeneration, and longitudinal cognitive and functional decline. A 10-point increase on baseline PRMQ increased the annual risk of diagnostic progression by approximately 70%. Study partner demographics and relationship to participants influenced reports of SMCs in AD participants only.

Conclusion

Partner-reported SMCs, using the PRMQ, have a stronger relationship with the neuroanatomic and cognitive changes associated with AD than patient-reported SMCs. Further work is needed to evaluate whether SMCs could be used to screen for future decline.

Distinct characteristics of limbic-predominant age-related TDP-43 encephalopathy in Lewy body disease

Limbic-predominant age-related TDP-43 encephalopathy (LATE) is characterized by the accumulation of TAR-DNA-binding protein 43 (TDP-43) aggregates in older adults. LATE coexists with Lewy body disease (LBD) as well as other neuropathological changes including Alzheimer's disease (AD). We aimed to identify the pathological, clinical, and genetic characteristics of LATE in LBD (LATE-LBD) by comparing it with LATE in AD (LATE-AD), LATE with mixed pathology of LBD and AD (LATE-LBD + AD), and LATE alone (Pure LATE). We analyzed four cohorts of autopsy-confirmed LBD (n = 313), AD (n = 282), LBD + AD (n = 355), and aging (n = 111). We assessed the association of LATE with patient profiles including LBD subtype and AD neuropathologic change (ADNC). We studied the morphological and distributional differences between LATE-LBD and LATE-AD. By frequency analysis, we staged LATE-LBD and examined the association with cognitive impairment and genetic risk factors. Demographic analysis showed LATE associated with age in all four cohorts and the frequency of LATE was the highest in LBD + AD followed by AD, LBD, and Aging. LBD subtype and ADNC associated with LATE in LBD or AD but not in LBD + AD. Pathological analysis revealed that the hippocampal distribution of LATE was different between LATE-LBD and LATE-AD: neuronal cytoplasmic inclusions were more frequent in cornu ammonis 3 (CA3) in LATE-LBD compared to LATE-AD and abundant fine neurites composed of C-terminal truncated TDP-43 were found mainly in CA2 to subiculum in LATE-LBD, which were not as numerous in LATE-AD. Some of these fine neurites colocalized with phosphorylated α-synuclein. LATE-LBD staging showed LATE neuropathological changes spread in the dentate gyrus and brainstem earlier than in LATE-AD. The presence and prevalence of LATE in LBD associated with cognitive impairment independent of either LBD subtype or ADNC; LATE-LBD stage also associated with the genetic risk variants of TMEM106B rs1990622 and GRN rs5848. These data highlight clinicopathological and genetic features of LATE-LBD.

Diagnosing Mild Cognitive Impairment Among Racially Diverse Older Adults: Comparison of Consensus, Actuarial, and Statistical Methods

BACKGROUND

Actuarial and statistical methods have been proposed as alternatives to conventional methods of diagnosing mild cognitive impairment (MCI), with the aim of enhancing diagnostic and prognostic validity, but have not been compared in racially diverse samples.

OBJECTIVE

We compared the agreement of consensus, actuarial, and statistical MCI diagnostic methods, and their relationship to race and prognostic indicators among diverse older adults.

METHODS

Participants (N = 354; M age = 71; 68% White, 29% Black) were diagnosed with MCI or normal cognition (NC) according to clinical consensus, actuarial neuropsychological criteria (Jak/Bondi), and latent class analysis (LCA). We examined associations with race/ethnicity, longitudinal cognitive and functional change, and incident dementia.

RESULTS

MCI rates by consensus, actuarial criteria, and LCA were 44%, 53%, and 41%, respectively. LCA identified three MCI subtypes (memory; memory/language; memory/executive) and two NC classes (low normal; high normal). Diagnostic agreement was substantial, but agreement of the actuarial method with consensus and LCA was weaker than the agreement between consensus and LCA. Among cases classified as MCI by actuarial criteria only, Black participants were over-represented, and outcomes were generally similar to those of NC participants. Consensus diagnoses best predicted longitudinal outcomes overall, whereas actuarial diagnoses best predicted longitudinal functional change among Black participants.

CONCLUSION

Consensus diagnoses optimize specificity in predicting dementia, but among Black older adults, actuarial diagnoses may be more sensitive to early signs of decline. Results highlight the need for cross-cultural validity in MCI diagnosis and should be explored in community- and population-based samples.

TMEM106B modifies TDP-43 pathology in human ALS brain and cell-based models of TDP-43 proteinopathy

The neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with TAR DNA-binding protein-43 (TDP-43) inclusions (FTLD-TDP) share the neuropathological hallmark of aggregates of TDP-43. However, factors governing the severity and regional distribution of TDP-43 pathology, which may account for the divergent clinical presentations of ALS and FTLD-TDP, are not well understood. Here, we investigated the influence of genotypes at TMEM106B, a locus associated with risk for FTLD-TDP, and hexanucleotide repeat expansions in C9orf72, a known genetic cause for both ALS and FTLD-TDP, on global TDP-43 pathology and regional distribution of TDP-43 pathology in 899 postmortem cases from a spectrum of neurodegenerative diseases. We found that, among the 110 ALS cases, minor (C)-allele homozygotes at the TMEM106B locus sentinel SNP rs1990622 had more TDP-43 pathology globally, as well as in select brain regions. C9orf72 expansions similarly associated with greater TDP-43 pathology in ALS. However, adjusting for C9orf72 expansion status did not affect the relationship between TMEM106B genotype and TDP-43 pathology. To elucidate the direction of causality for this association, we directly manipulated TMEM106B levels in an inducible cell system that expresses mislocalized TDP-43 protein. We found that partial knockdown of TMEM106B, to levels similar to what would be expected in rs1990622 C allele carriers, led to development of more TDP-43 cytoplasmic aggregates, which were more insoluble, in this system. Taken together, our results support a causal role for TMEM106B in modifying the development of TDP-43 proteinopathy.

α-Synuclein modulates tau spreading in mouse brains

α-Synuclein (α-syn) and tau aggregates are the neuropathological hallmarks of Parkinson’s disease (PD) and Alzheimer’s disease (AD), respectively, although both pathologies co-occur in patients with these diseases, suggesting possible crosstalk between them. To elucidate the interactions of pathological α-syn and tau, we sought to model these interactions. We show that increased accumulation of tau aggregates occur following simultaneous introduction of α-syn mousepreformed fibrils (mpffs) and AD lysate–derived tau seeds (AD-tau) both in vitro and in vivo. Interestingly, the absence of endogenous mouse α-syn in mice reduces the accumulation and spreading of tau, while the absence of tau did not affect the seeding or spreading capacity of α-syn. These in vivo results are consistent with our in vitro data wherein the presence of tau has no synergistic effects on α-syn. Our results point to the important role of α-syn as a modulator of tau pathology burden and spreading in the brains of AD, PDD, and DLB patients.

Longitudinal naming and repetition relates to AD pathology and burden in autopsy-confirmed primary progressive aphasia

INTRODUCTION

In primary progressive aphasia (PPA) patients with autopsy-confirmed Alzheimer's disease (AD) or frontotemporal lobar degeneration (FLTD), we tested how the core clinical features of logopenic PPA-naming and repetition-change over time and relate to pathologic burden.

METHODS

In PPA with AD (n = 13) or FTLD (n = 16) pathology, Boston Naming Test and Forward Digit Span measured longitudinal naming and repetition; as reference, Mini-Mental State Examination (MMSE) measured global cognition. Pathologic burden in left peri-Sylvian regions was related to longitudinal cognitive decline.

RESULTS

PPA with AD showed greater decline in naming (P = 0.021) and repetition (P = 0.020), compared to FTLD; there was no difference in MMSE decline (P = 0.99). Across all PPA, declining naming (P = 0.0084) and repetition (P = 0.011) were associated with angular, superior-middle temporal (naming P = 0.014; repetition P = 0.011) and middle frontal (naming P = 0.041; repetition P = 0.030) pathologic burden.

DISCUSSION

Unique longitudinal profiles of naming and repetition performance in PPA with AD are related to left peri-Sylvian pathology.

NDDRF: a risk factor knowledgebase for personalized prevention of neurodegenerative diseases

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A risk factor knowledgebase (NDDRF) is built for neurodegenerative diseases (NDDs).

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NDDRF collects the risk factors associated with diagnosis and prevention of NDDs.

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NDDRF is helpful to the systematic understanding of the heterogeneous NDDs

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NDDRF provides knowledge for personalized diagnosis and prevention of NDDs.

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NDDRF can be used to the future explainable artificial intelligent modeling.

Introduction

Neurodegenerative diseases (NDDs) are a series of chronic diseases, which are associated with progressive loss of neuronal structure or function. The complex etiologies of the NDDs remain unclear, thus the prevention and early diagnosis of NDDs are critical to reducing the mortality and morbidity of these diseases.

Objectives

To provide a systematic understanding of the heterogeneity of the risk factors associated with different NDDs (pan-neurodegenerative diseases or pan-NDDs), the knowledgebase is established to facilitate the personalized and knowledge-guided diagnosis, prevention and prediction of NDDs.

Methods

Before data collection, the medical, life science and informatics experts as well as the potential users of the database were consulted and discussed for the scope of data and the classification of risk factors. The PubMed database was used as the resource of the data and knowledge extraction. Risk factors of NDDs were manually collected from literature published between 1975 and 2020.

Results

The comprehensive risk factors database for NDDs (NDDRF) was established including 998 single or combined risk factors, 2293 records and 1071 articles relevant to the 14 most common NDDs. The single risk factors are classified into 3 categories, i.e. epidemiological factors (469), genetic factors (324) and biochemical factors (153). Among all the factors, 179 factors are positive and protective, while 880 factors have negative influence for NDDs. The knowledgebase is available at http://sysbio.org.cn/NDDRF/.

Conclusion

NDDRF provides the structured information and knowledge resource on risk factors of NDDs. It could benefit the future systematic and personalized investigation of pan-NDDs genesis and progression. Meanwhile it may be used for the future explainable artificial intelligence modeling for smart diagnosis and prevention of NDDs.

Frontotemporal lobar degeneration proteinopathies have disparate microscopic patterns of white and grey matter pathology

Frontotemporal lobar degeneration proteinopathies with tau inclusions (FTLD-Tau) or TDP-43 inclusions (FTLD-TDP) are associated with clinically similar phenotypes. However, these disparate proteinopathies likely differ in cellular severity and regional distribution of inclusions in white matter (WM) and adjacent grey matter (GM), which have been understudied. We performed a neuropathological study of subcortical WM and adjacent GM in a large autopsy cohort (n = 92; FTLD-Tau = 37, FTLD-TDP = 55) using a validated digital image approach. The antemortem clinical phenotype was behavioral-variant frontotemporal dementia (bvFTD) in 23 patients with FTLD-Tau and 42 with FTLD-TDP, and primary progressive aphasia (PPA) in 14 patients with FTLD-Tau and 13 with FTLD-TDP. We used linear mixed-effects models to: (1) compare WM pathology burden between proteinopathies; (2) investigate the relationship between WM pathology burden and WM degeneration using luxol fast blue (LFB) myelin staining; (3) study regional patterns of pathology burden in clinico-pathological groups. WM pathology burden was greater in FTLD-Tau compared to FTLD-TDP across regions (beta = 4.21, SE = 0.34, p < 0.001), and correlated with the degree of WM degeneration in both FTLD-Tau (beta = 0.32, SE = 0.10, p = 0.002) and FTLD-TDP (beta = 0.40, SE = 0.08, p < 0.001). WM degeneration was greater in FTLD-Tau than FTLD-TDP particularly in middle-frontal and anterior cingulate regions (p < 0.05). Distinct regional patterns of WM and GM inclusions characterized FTLD-Tau and FTLD-TDP proteinopathies, and associated in part with clinical phenotype. In FTLD-Tau, WM pathology was particularly severe in the dorsolateral frontal cortex in nonfluent-variant PPA, and GM pathology in dorsolateral and paralimbic frontal regions with some variation across tauopathies. Differently, FTLD-TDP had little WM regional variability, but showed severe GM pathology burden in ventromedial prefrontal regions in both bvFTD and PPA. To conclude, FTLD-Tau and FTLD-TDP proteinopathies have distinct severity and regional distribution of WM and GM pathology, which may impact their clinical presentation, with overall greater severity of WM pathology as a distinguishing feature of tauopathies.

ATN status in amnestic and non-amnestic Alzheimer's disease and frontotemporal lobar degeneration

Under the ATN framework, CSF analytes provide evidence of the presence or absence of Alzheimer's disease pathological hallmarks: amyloid plaques (A), phosphorylated tau (T), and accompanying neurodegeneration (N). Still, differences in CSF levels across amnestic and non-amnestic variants or due to co-occurring pathologies might lead to misdiagnoses. We assess the diagnostic accuracy of CSF markers for amyloid, tau, and neurodegeneration in an autopsy cohort of 118 Alzheimer's disease patients (98 amnestic; 20 non-amnestic) and 64 frontotemporal lobar degeneration patients (five amnestic; 59 non-amnestic). We calculated between-group differences in CSF concentrations of amyloid-β1-42 peptide, tau protein phosphorylated at threonine 181, total tau, and the ratio of phosphorylated tau to amyloid-β1-42. Results show that non-amnestic Alzheimer's disease patients were less likely to be correctly classified under the ATN framework using independent, published biomarker cut-offs for positivity. Amyloid-β1-42 did not differ between amnestic and non-amnestic Alzheimer's disease, and receiver operating characteristic curve analyses indicated that amyloid-β1-42 was equally effective in discriminating both groups from frontotemporal lobar degeneration. However, CSF concentrations of phosphorylated tau, total tau, and the ratio of phosphorylated tau to amyloid-β1-42 were significantly lower in non-amnestic compared to amnestic Alzheimer's disease patients. Receiver operating characteristic curve analyses for these markers showed reduced area under the curve when discriminating non-amnestic Alzheimer's disease from frontotemporal lobar degeneration, compared to discrimination of amnestic Alzheimer's disease from frontotemporal lobar degeneration. In addition, the ATN framework was relatively insensitive to frontotemporal lobar degeneration, and these patients were likely to be classified as having normal biomarkers or biomarkers suggestive of primary Alzheimer's disease pathology. We conclude that amyloid-β1-42 maintains high sensitivity to A status, although with lower specificity, and this single biomarker provides better sensitivity to non-amnestic Alzheimer's disease than either the ATN framework or the phosphorylated-tau/amyloid-β1-42 ratio. In contrast, T and N status biomarkers differed between amnestic and non-amnestic Alzheimer's disease; standard cut-offs for phosphorylated tau and total tau may thus result in misclassifications for non-amnestic Alzheimer's disease patients. Consideration of clinical syndrome may help improve the accuracy of ATN designations for identifying true non-amnestic Alzheimer's disease.

ATN incorporating cerebrospinal fluid neurofilament light chain detects frontotemporal lobar degeneration

INTRODUCTION

The ATN framework provides an in vivo diagnosis of Alzheimer's disease (AD) using cerebrospinal fluid (CSF) biomarkers of pathologic amyloid plaques (A), tangles (T), and neurodegeneration (N). ATN is rarely evaluated in pathologically confirmed patients and its poor sensitivity to suspected non-Alzheimer's pathophysiologies (SNAP), including frontotemporal lobar degeneration (FTLD), leads to misdiagnoses. We compared accuracy of ATN (ATN_TAU ) using CSF total tau (t-tau) to a modified strategy (ATN_NfL ) using CSF neurofilament light chain (NfL) in an autopsy cohort.

METHODS

ATN_TAU and ATN_NfL were trained in an independent sample and validated in autopsy-confirmed AD (n = 67) and FTLD (n = 27).

RESULTS

ATN_NfL more accurately identified FTLD as SNAP (sensitivity = 0.93, specificity = 0.94) than ATN_TAU (sensitivity = 0.44, specificity = 0.97), even in cases with co-occurring AD and FTLD. ATN_NfL misclassified fewer AD and FTLD as "Normal" (2%) than ATN_TAU (14%).

DISCUSSION

ATN_NfL is a promising diagnostic strategy that may accurately identify both AD and FTLD, even when pathologies co-occur.

Degeneration of the locus coeruleus is a common feature of tauopathies and distinct from TDP-43 proteinopathies in the frontotemporal lobar degeneration spectrum

Neurodegeneration of the locus coeruleus (LC) in age-related neurodegenerative diseases such as Alzheimer's disease (AD) is well documented. However, detailed studies of LC neurodegeneration in the full spectrum of frontotemporal lobar degeneration (FTLD) proteinopathies comparing tauopathies (FTLD-tau) to TDP-43 proteinopathies (FTLD-TDP) are lacking. Here, we tested the hypothesis that there is greater LC neuropathology and neurodegeneration in FTLD-tau compared to FTLD-TDP. We examined 280 patients including FTLD-tau (n = 94), FTLD-TDP (n = 135), and two reference groups: clinical/pathological AD (n = 32) and healthy controls (HC, n = 19). Adjacent sections of pons tissue containing the LC were immunostained for phosphorylated TDP-43 (1D3-p409/410), hyperphosphorylated tau (PHF-1), and tyrosine hydroxylase (TH) to examine neuromelanin-containing noradrenergic neurons. Blinded to clinical and pathologic diagnoses, we semi-quantitatively scored inclusions of tau and TDP-43 both inside LC neuronal somas and in surrounding neuropil. We also digitally measured the percent area occupied of neuromelanin inside of TH-positive LC neurons and in surrounding neuropil to calculate a ratio of extracellular-to-intracellular neuromelanin as an objective composite measure of neurodegeneration. We found that LC tau burden in FTLD-tau was greater than LC TDP-43 burden in FTLD-TDP (z = - 11.38, p < 0.0001). Digital measures of LC neurodegeneration in FTLD-tau were comparable to AD (z = - 1.84, p > 0.05) but greater than FTLD-TDP (z = - 3.85, p < 0.0001) and HC (z = - 4.12, p < 0.0001). Both tau burden and neurodegeneration were consistently elevated in the LC across pathologic and clinical subgroups of FTLD-tau compared to FTLD-TDP subgroups. Moreover, LC tau burden positively correlated with neurodegeneration in the total FTLD group (rho = 0.24, p = 0.001), while TDP-43 burden did not correlate with LC neurodegeneration in FTLD-TDP (rho = - 0.01, p = 0.90). These findings suggest that patterns of disease propagation across all tauopathies include prominent LC tau and neurodegeneration that are relatively distinct from the minimal degenerative changes to the LC in FTLD-TDP and HC. Antemortem detection of LC neurodegeneration and/or function could potentially improve antemortem differentiation of underlying FTLD tauopathies from clinically similar FTLD-TDP proteinopathies.

Defining and predicting transdiagnostic categories of neurodegenerative disease

The prevalence of concomitant proteinopathies and heterogeneous clinical symptoms in neurodegenerative diseases hinders the identification of individuals who might be candidates for a particular intervention. Here, by applying an unsupervised clustering algorithm to post-mortem histopathological data from 895 patients with degeneration in the central nervous system, we show that six non-overlapping disease clusters can simultaneously account for tau neurofibrillary tangles, α-synuclein inclusions, neuritic plaques, inclusions of the transcriptional repressor TDP-43, angiopathy, neuron loss and gliosis. We also show that membership to the six transdiagnostic disease clusters, which explains more variance in cognitive phenotypes than can be explained by individual diagnoses, can be accurately predicted from scores of the Mini-Mental Status Exam, protein levels in cerebrospinal fluid, and genotype at the APOE and MAPT loci, via cross-validated multiple logistic regression. This combination of unsupervised and supervised data-driven tools provides a framework that could be used to identify latent disease subtypes in other areas of medicine.

Association of Cerebrospinal Fluid Neurofilament Light Protein Levels With Cognition in Patients With Dementia, Motor Neuron Disease, and Movement Disorders

Importance

Neuronal and axonal destruction are hallmarks of neurodegenerative diseases, but it is difficult to estimate the extent and progress of the damage in the disease process.

Objective

To investigate cerebrospinal fluid (CSF) levels of neurofilament light (NFL) protein, a marker of neuroaxonal degeneration, in control participants and patients with dementia, motor neuron disease, and parkinsonian disorders (determined by clinical criteria and autopsy), and determine its association with longitudinal cognitive decline.

Design, Setting, and Participants

In this case-control study, we investigated NFL levels in CSF obtained from controls and patients with several neurodegenerative diseases. Collection of samples occurred between 1996 and 2014, patients were followed up longitudinally for cognitive testing, and a portion were autopsied in a single center (University of Pennsylvania). Data were analyzed throughout 2016.

Exposures

Concentrations of NFL in CSF.

Main Outcomes and Measures

Levels of CSF NFL and correlations with cognition scores.

Results

A total of 913 participants (mean [SD] age, 68.7 [10.0] years; 456 [49.9%] women) were included: 75 control participants plus 114 patients with mild cognitive impairment (MCI), 397 with Alzheimer disease, 96 with frontotemporal dementia, 68 with amyotrophic lateral sclerosis, 41 with Parkinson disease (PD), 19 with PD with MCI, 29 with PD dementia, 33 with dementia with Lewy bodies, 21 with corticobasal syndrome, and 20 with progressive supranuclear palsy. Cognitive testing follow-up occurred for 1 to 18 years (mean [SD], 0.98 [2.25] years); autopsy-verified diagnoses were available for 120 of 845 participants with diseases (14.2%). There was a stepwise increase in CSF NFL levels between control participants (median [range] score, 536 [398-777] pg/mL), participants with MCI (831 [526-1075] pg/mL), and those with Alzheimer disease (951 [758-1261] pg/mL), indicating that NFL levels increase with increasing cognitive impairment. Levels of NFL correlated inversely with baseline Mini-Mental State Examination scores (ρ, -0.19; P < .001) in the full cohort (n = 822) and annual score decline in the full cohort (ρ, 0.36, P < .001), participants with AD (ρ, 0.25; P < .001), and participants with FTD (ρ, 0.46; P = .003). Concentrations of NFL were highest in participants with amyotrophic lateral sclerosis (median [range], 4185 [2207-7453] pg/mL) and frontotemporal dementia (2094 [230-7744] pg/mL). In individuals with parkinsonian disorders, NFL concentrations were highest in those with progressive supranuclear palsy (median [range], 1578 [1287-3104] pg/mL) and corticobasal degeneration (1281 [828-2713] pg/mL). The NFL concentrations in CSF correlated with TDP-43 load in 13 of 17 brain regions in the full cohort. Adding NFL to β-amyloid 42, total tau, and phosphorylated tau increased accuracy of discrimination of diseases.

Conclusions and Relevance

Levels of CSF NFL are associated with cognitive impairments in patients with Alzheimer disease and frontotemporal dementia. In other neurodegenerative disorders, NFL levels appear to reflect the intensity of the neurodegenerative processes.

Converging Patterns of α-Synuclein Pathology in Multiple System Atrophy

We aimed to determine patterns of α-synuclein (α-syn) pathology in multiple system atrophy (MSA) using 70-µm-thick sections of 20 regions of the central nervous system of 37 cases with striato-nigral degeneration (SND) and 10 cases with olivo-ponto-cerebellar atrophy (OPCA). In SND cases with the shortest disease duration (phase 1), α-syn pathology was observed in striatum, lentiform nucleus, substantia nigra, brainstem white matter tracts, cerebellar subcortical white matter as well as motor cortex, midfrontal cortex, and sensory cortex. SND with increasing duration of disease (phase 2) was characterized by involvement of spinal cord and thalamus, while phase 3 was characterized by involvement of hippocampus and amygdala. Cases with the longest disease duration (phase 4) showed involvement of the visual cortex. We observed an increasing overlap of α-syn pathology with increasing duration of disease between SND and OPCA, and noted increasingly similar regional distribution patterns of α-syn pathology. The GBA variant, p.Thr408Met, was found to have an allele frequency of 6.94% in SND cases which was significantly higher compared with normal (0%) and other neurodegenerative disease pathologies (0.74%), suggesting that it is associated with MSA. Our findings indicate that SND and OPCA show distinct early foci of α-syn aggregations, but increasingly converge with longer disease duration to show overlapping patterns of α-syn pathology.

Impact of TREM2 risk variants on brain region-specific immune activation and plaque microenvironment in Alzheimer's disease patient brain samples

Identification of multiple immune-related genetic risk factors for sporadic AD (sAD) have put the immune system center stage in mechanisms underlying this disorder. Comprehensive analysis of microglia in different stages of AD in human brains revealed microglia activation to follow the progression of AD neuropathological changes and requiring the co-occurrence of beta-Amyloid (Aβ) and tau pathology. Carriers of AD-associated risk variants in TREM2 (Triggering receptor expressed on myeloid cells 2) showed a reduction of plaque-associated microglia and a substantial increase in dystrophic neurites and overall pathological tau compared with age and disease stage matched AD patients without TREM2 risk variants. These findings were substantiated by digital spatial profiling of the plaque microenvironment and targeted gene expression profiling on the NanoString nCounter system, which revealed striking brain region dependent differences in immune response patterns within individual cases. The demonstration of profound brain region and risk-variant specific differences in immune activation in human AD brains impacts the applicability of immune-therapeutic approaches for sAD and related neurodegenerative diseases.

Musical and Cognitive Abilities in Older Adults with Mild Cognitive Impairment

The objective of this cross-sectional study was to determine the extent and nature of self-reported musical abilities in persons with mild cognitive impairment (MCI). We recruited 60 older adults with a diagnosis of MCI from the Alzheimer's disease Core Center. We evaluated self-reported musical abilities using the Goldsmiths General Musical Sophistication Index. We examined correlations between musical abilities and neuropsychological measures of verbal learning and memory, processing speed, executive function, verbal fluency, naming and visuoconstructive abilities, while controlling for key demographic and participant characteristics. Older adults with MCI reported varying degrees of musical abilities. Nearly half of participants reported that they did not engage in regular, daily practice of a musical instrument. When adjusting for key demographic and participant characteristics, we found modest associations between four musical ability subfactors (active engagement, perceptual abilities, musical training and emotional engagement with music) with three cognitive abilities: verbal fluency, executive function and verbal naming. Except for the emotional engagement with music subfactor, none of the remaining musical ability subfactors correlated with any demographic or participant characteristics. While our study findings provided further support for the relationship between musical and cognitive abilities in older adults with MCI, this relationship warrants further investigation.

Divergent patterns of TDP-43 and tau pathologies in primary progressive aphasia

OBJECTIVE

To measure postmortem burden of frontotemporal lobar degeneration (FTLD) with TDP-43 (FTLD-TDP) or tau (FTLD-Tau) proteinopathy across hemispheres in primary progressive aphasia (PPA) using digital histopathology and to identify clinicopathological correlates of these distinct proteinopathies.

METHODS

In an autopsy cohort of PPA (FTLD-TDP = 13, FTLD-Tau = 14), we analyzed laterality and regional distribution of postmortem pathology, quantified using a validated digital histopathological approach, in available brain tissue from up to 8 cortical regions bilaterally. We related digital pathology to antemortem structural neuroimaging and specific clinical language features.

RESULTS

Postmortem cortical pathology was left-lateralized in both FTLD-TDP (beta = -0.15, standard error [SE] = 0.05, p = 0.007) and FTLD-Tau (beta = -0.09, SE = 0.04, p = 0.015), but the degree of lateralization decreased with greater overall dementia severity before death (beta = -8.18, SE = 3.22, p = 0.015). Among 5 core pathology regions sampled, we found greatest pathology in left orbitofrontal cortex (OFC) in FTLD-TDP, which was greater than in FTLD-Tau (F = 47.07, df = 1,17, p < 0.001), and in left midfrontal cortex (MFC) in FTLD-Tau, which was greater than in FTLD-TDP (F = 19.34, df = 1,16, p < 0.001). Postmortem pathology was inversely associated with antemortem magnetic resonance imaging cortical thickness (beta = -0.04, SE = 0.01, p = 0.007) in regions matching autopsy sampling. Irrespective of PPA syndromic variant, single-word comprehension impairment was associated with greater left OFC pathology (t = -3.72, df = 10.72, p = 0.004) and nonfluent speech with greater left MFC pathology (t = -3.62, df = 12.00, p = 0.004) among the 5 core pathology regions.

INTERPRETATION

In PPA, FTLD-TDP and FTLD-Tau have divergent anatomic distributions of left-lateralized postmortem pathology that relate to antemortem structural imaging and distinct language deficits. Although other brain regions may be implicated in neural networks supporting these complex language measures, our observations may eventually help to improve antemortem diagnosis of neuropathology in PPA. Ann Neurol 2019;85:630-643.

Asymmetry of post-mortem neuropathology in behavioural-variant frontotemporal dementia

Antemortem behavioural and anatomic abnormalities have largely been associated with right hemisphere disease in behavioural-variant frontotemporal dementia, but post-mortem neuropathological examination of bilateral hemispheres remains to be defined. Here we measured the severity of post-mortem pathology in both grey and white matter using a validated digital image analysis method in four cortical regions sampled from each hemisphere in 26 patients with behavioural-variant frontotemporal dementia, including those with frontotemporal degeneration (i.e. tau = 9, TDP-43 = 14, or FUS = 1 proteinopathy) or Alzheimer's pathology (n = 2). We calculated an asymmetry index based on the difference in measured pathology from each left-right sample pair. Analysis of the absolute value of the asymmetry index (i.e. degree of asymmetry independent of direction) revealed asymmetric pathology for both grey and white matter in all four regions sampled in frontototemporal degeneration patients with tau or TDP-43 pathology (P ≤ 0.01). Direct interhemispheric comparisons of regional pathology measurements within-subjects in the combined tauopathy and TDP-43 proteinopathy group found higher pathology in the right orbitofrontal grey matter compared to the left (P < 0.01) and increased pathology in ventrolateral temporal lobe grey matter of the left hemisphere compared to the right (P < 0.02). Preliminary group-wise comparisons between tauopathy and TDP-43 proteinopathy groups found differences in patterns of interhemispheric burden of grey and white matter regional pathology, with greater relative white matter pathology in tauopathies. To test the association of pathology measurement with ante-mortem observations, we performed exploratory analyses in the subset of patients with imaging data (n = 15) and found a direct association for increasing pathologic burden with decreasing cortical thickness in frontotemporal regions on ante-mortem imaging in tauopathy (P = 0.001) and a trend for TDP-43 proteinopathy (P = 0.06). Exploratory clinicopathological correlations demonstrated an association of socially-inappropriate behaviours with asymmetric right orbitofrontal grey matter pathology, and reduced semantically-guided category naming fluency was associated asymmetric white matter pathology in the left ventrolateral temporal region. We conclude that pathologic disease burden is distributed asymmetrically in behavioural-variant frontotemporal dementia, although not universally in the right hemisphere, and this asymmetry contributes to the clinical heterogeneity of the disorder. The basis for this asymmetric profile is enigmatic but may reflect distinct species or strains of tau and TDP-43 pathologies with propensities to spread by distinct cell- and region-specific mechanisms. Patterns of region-specific pathology in the right hemisphere as well as the left hemisphere may play a role in antemortem clinical observations, and these observations may contribute to antemortem identification of molecular pathology in frontotemporal degeneration.

Detection of Alzheimer's disease (AD) specific tau pathology with conformation-selective anti-tau monoclonal antibody in co-morbid frontotemporal lobar degeneration-tau (FTLD-tau)

Pathological tau aggregates in Alzheimer’s disease (AD) and frontotemporal lobar degeneration-tau (FTLD-tau) adopt distinct conformations differentiated by the AD-tau specific monoclonal antibody (mAb) GT-38 that are not readily visualized using phosphorylation-specific anti-tau mAbs. To determine the extent of co-morbid AD-tau pathology in FTLD-tau, we performed immunohistochemical (IHC) staining with GT-38 and assigned Braak stages of AD-tau in a cohort 180 FTLD-tau cases consisting of corticobasal degeneration (CBD; n = 49), progressive supranuclear palsy (PSP; n = 109), and Pick’s disease (PiD; n = 22). Nearly two-thirds of patients (n = 115 of 180, 63.8%) with FTLD-tau had some degree of comorbid AD-tau pathology and 20.5% of the FTLD-tau cohort had Braak stage ≥B2, consistent with medium-to-high-level AD neuropathological change (ADNPC). The PSP group had the highest frequency of medium-high AD-tau pathology compared to other tauopathies (PSP = 31/109, 28.4%; Picks = 2/22, 9.1%, CBD = 4/49, 8.2%) but neuropathological diagnosis was not found to be a significant independent predictor of medium-high AD Braak stage in a multivariate model after accounting for age at death (OR = 1.09; 95% CI = 1.03–1.15; p = 0.002) and CERAD plaque scores (OR = 3.75, 95% CI = 1.58–8.89; p = 0.003), suggesting there is no predilection for a specific FTLD tauopathy to develop AD-tau co-pathology after accounting for age. Patients with FTLD-tau who had, clinically significant, medium-high AD-tau pathology had significantly higher antemortem CSF levels of both total-tau (t-tau; mean = 89.98 pg/ml, SD = 36.70 pg/ml) and phosphorylated-tau (p-tau; mean = 20.45 pg/ml, SD = 9.31 pg/ml) compared to patients with negligible-low AD-tau, t-tau (mean = 43.04 pg/ml, SD = 25.40 pg/ml) and p-tau (mean = 11.90 pg/ml, SD = 4.48 pg/ml) (p ≤ 0.001 both). Finally, in an exploratory analysis in our largest pathology group (PSP) we find an association of GT-38 AD-tau Braak stage with lower baseline MMSE (p = 0.03). Together, these finding validate the use of GT-38 to selectively detect AD-tau pathology in the context of FTLD-tau and provides a novel tool to investigate associations of clinical phenotypes amongst co-morbid tauopathies.

Converging Patterns of α-Synuclein Pathology in Multiple System Atrophy

We aimed to determine patterns of α-synuclein (α-syn) pathology in multiple system atrophy (MSA) using 70-µm-thick sections of 20 regions of the central nervous system of 37 cases with striato-nigral degeneration (SND) and 10 cases with olivo-ponto-cerebellar atrophy (OPCA). In SND cases with the shortest disease duration (phase 1), α-syn pathology was observed in striatum, lentiform nucleus, substantia nigra, brainstem white matter tracts, cerebellar subcortical white matter as well as motor cortex, midfrontal cortex, and sensory cortex. SND with increasing duration of disease (phase 2) was characterized by involvement of spinal cord and thalamus, while phase 3 was characterized by involvement of hippocampus and amygdala. Cases with the longest disease duration (phase 4) showed involvement of the visual cortex. We observed an increasing overlap of α-syn pathology with increasing duration of disease between SND and OPCA, and noted increasingly similar regional distribution patterns of α-syn pathology. The GBA variant, p.Thr408Met, was found to have an allele frequency of 6.94% in SND cases which was significantly higher compared with normal (0%) and other neurodegenerative disease pathologies (0.74%), suggesting that it is associated with MSA. Our findings indicate that SND and OPCA show distinct early foci of α-syn aggregations, but increasingly converge with longer disease duration to show overlapping patterns of α-syn pathology.

Cerebrospinal fluid neurogranin concentration in neurodegeneration: relation to clinical phenotypes and neuropathology

Neurogranin (Ng) is a post-synaptic protein that previously has been shown to be a biomarker for synaptic function when measured in cerebrospinal fluid (CSF). The CSF concentration of Ng is increased in Alzheimer’s disease dementia (ADD), and even in the pre-dementia stage. In this prospective study, we used an enzyme-linked immunosorbent assay that quantifies Ng in CSF to test the performance of Ng as a marker of synaptic function. In 915 patients, CSF Ng was evaluated across several different neurodegenerative diseases. Of these 915 patients, 116 had a neuropathologically confirmed definitive diagnosis and the relation between CSF Ng and topographical distribution of different pathologies in the brain was evaluated. CSF Ng was specifically increased in ADD compared to eight other neurodegenerative diseases, including Parkinson’s disease (p < 0.0001), frontotemporal dementia (p < 0.0001), and amyotrophic lateral sclerosis (p = 0.0002). Similar results were obtained in neuropathologically confirmed cases. Using a biomarker index to evaluate whether CSF Ng contributed diagnostic information to the core AD CSF biomarkers (amyloid β (Aβ), t-tau, and p-tau), we show that Ng significantly increased the discrimination between AD and several other disorders. Higher CSF Ng levels were positively associated with greater Aβ neuritic plaque (Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) neuritic plaque score, p = 0.0002) and tau tangle pathology (Braak neurofibrillary tangles staging, p = 0.0007) scores. In the hippocampus and amygdala, two brain regions heavily affected in ADD with high expression of Ng, CSF Ng was associated with plaque (p = 0.0006 and p < 0.0001), but not with tangle, α-synuclein, or TAR DNA-binding protein 43 loads. These data support that CSF Ng is increased specifically in ADD, that high CSF Ng concentrations likely reflect synaptic dysfunction and that CSF Ng is associated with β-amyloid plaque pathology.

Alzheimer's genetic risk is reduced in primary age-related tauopathy: a potential model of resistance?

Objective

Nearly all adults >50 years of age have evidence for neurofibrillary tau tangles (NFTs) and a significant proportion of individuals additionally develop amyloid plaques (Aβ) consistent with Alzheimer's disease (AD). In an effort to identify the independent genetic risk factors for NFTs and Aβ, we investigated genotypic frequencies of AD susceptibility loci between autopsy‐confirmed AD and primary age‐related tauopathy (PART), a neuropathological condition defined by characteristic neurofibrillary tau tangles (NFTs) with minimal or absent Aβ.

Methods

General linear models assessed the odds of AD (N = 1190) relative to PART (N = 376) neuropathologically confirmed cases from two independent series: the Penn Brain Bank (PENN; AD N = 312; PART N = 65) and National Alzheimer's Coordinating Center (NACC; AD N = 878; PART N = 311). We also evaluated the odds of Braak stage NFT burden.

Results

Three genotypes significantly associated with reduced AD risk relative to PART in the PENN (N = 377) and NACC (N = 1189) cohorts including APOE ε4, APOE ε2, and rs6656401 in the CR1 gene. The genotypes rs6733839 in the BIN1 gene and rs28834970 in the PTK2B gene approached significance in the PENN cohort and were significantly associated with reduced AD risk in the NACC cohort. In a combined cohort analysis (N = 1566), APOE ε4 dosage was highly associated with higher Braak stage of NFT burden in Probable PART and AD, but not Definite PART.

Interpretation

The presence of genotypic differences between PART and AD suggest that PART can provide a genetic model of NFT risk and potential Aβ resistance to inform disease‐modifying therapies.

CSF tau and β-amyloid predict cerebral synucleinopathy in autopsied Lewy body disorders

OBJECTIVE

To test the association of antemortem CSF biomarkers with postmortem pathology in Lewy body disorders (LBD).

METHODS

Patients with autopsy-confirmed LBD (n = 24) and autopsy-confirmed Alzheimer disease (AD) (n = 23) and cognitively normal (n = 36) controls were studied. In LBD, neuropathologic criteria defined Lewy body α-synuclein (SYN) stages with medium/high AD copathology (SYN + AD = 10) and low/no AD copathology (SYN - AD = 14). Ordinal pathology scores for tau, β-amyloid (Aβ), and SYN pathology were averaged across 7 cortical regions to obtain a global cerebral score for each pathology. CSF total tau (t-tau), phosphorylated tau at threonine181, and Aβ1-42 levels were compared between LBD and control groups and correlated with global cerebral pathology scores in LBD with linear regression. Diagnostic accuracy for postmortem categorization of LBD into SYN + AD vs SYN - AD or neocortical vs brainstem/limbic SYN stage was tested with receiver operating curves.

RESULTS

SYN + AD had higher CSF t-tau (mean difference 27.0 ± 8.6 pg/mL) and lower Aβ1-42 (mean difference -84.0 ± 22.9 g/mL) compared to SYN - AD (p < 0.01, both). Increasing global cerebral tau and plaque scores were associated with higher CSF t-tau (R2 = 0.15-0.16, p < 0.05, both) and lower Aβ1-42 (R2 = 0.43-0.49, p < 0.001, both), while increasing cerebral SYN scores were associated with lower CSF Aβ1-42 (R2 = 0.31, p < 0.001) and higher CSF t-tau/Aβ1-42 ratio (R2 = 0.27, p = 0.01). CSF t-tau/Aβ1-42 ratio had 100% specificity and 90% sensitivity for SYN + AD, and CSF Aβ1-42 had 77% specificity and 82% sensitivity for neocortical SYN stage.

CONCLUSIONS

Higher antemortem CSF t-tau/Aβ1-42 and lower Aβ1-42 levels are predictive of increasing cerebral AD and SYN pathology. These biomarkers may identify patients with LBD vulnerable to cortical SYN pathology who may benefit from both SYN and AD-targeted disease-modifying therapies.

Global Data Sharing in Alzheimer Disease Research

Many investigators recognize the importance of data sharing; however, they lack the capability to share data. Research efforts could be vastly expanded if Alzheimer disease data from around the world was linked by a global infrastructure that would enable scientists to access and utilize a secure network of data with thousands of study participants at risk for or already suffering from the disease. We discuss the benefits of data sharing, impediments today, and solutions to achieving this on a global scale. We introduce the Global Alzheimer's Association Interactive Network (GAAIN), a novel approach to create a global network of Alzheimer disease data, researchers, analytical tools, and computational resources to better our understanding of this debilitating condition. GAAIN has addressed the key impediments to Alzheimer disease data sharing with its model and approach. It presents practical, promising, yet, data owner-sensitive data-sharing solutions.

Clinical marker for Alzheimer disease pathology in logopenic primary progressive aphasia

OBJECTIVE

To determine whether logopenic features of phonologic loop dysfunction reflect Alzheimer disease (AD) neuropathology in primary progressive aphasia (PPA).

METHODS

We performed a retrospective case-control study of 34 patients with PPA with available autopsy tissue. We compared baseline and longitudinal clinical features in patients with primary AD neuropathology to those with primary non-AD pathologies. We analyzed regional neuroanatomic disease burden in pathology-defined groups using postmortem neuropathologic data.

RESULTS

A total of 19/34 patients had primary AD pathology and 15/34 had non-AD pathology (13 frontotemporal lobar degeneration, 2 Lewy body disease). A total of 16/19 (84%) patients with AD had a logopenic spectrum phenotype; 5 met published criteria for the logopenic variant (lvPPA), 8 had additional grammatical or semantic deficits (lvPPA+), and 3 had relatively preserved sentence repetition (lvPPA-). Sentence repetition was impaired in 68% of patients with PPA with AD pathology; forward digit span (DF) was impaired in 90%, substantially higher than in non-AD PPA (33%, p < 0.01). Lexical retrieval difficulty was common in all patients with PPA and did not discriminate between groups. Compared to non-AD, PPA with AD pathology had elevated microscopic neurodegenerative pathology in the superior/midtemporal gyrus, angular gyrus, and midfrontal cortex (p < 0.01). Low DF scores correlated with high microscopic pathologic burden in superior/midtemporal and angular gyri (p ≤ 0.03).

CONCLUSIONS

Phonologic loop dysfunction is a central feature of AD-associated PPA and specifically correlates with temporoparietal neurodegeneration. Quantitative measures of phonologic loop function, combined with modified clinical lvPPA criteria, may help discriminate AD-associated PPA.

Progression of alpha-synuclein pathology in multiple system atrophy of the cerebellar type

AIMS

The aim of this study was to identify early foci of α-synuclein (α-syn pathology) accumulation, subsequent progression and neurodegeneration in multiple system atrophy of the cerebellar type (MSA-C).

METHODS

We analysed 70-μm-thick sections of 10 cases with MSA-C and 24 normal controls.

RESULTS

MSA-C cases with the lowest burden of pathology showed α-syn glial cytoplasmic inclusions (GCIs) in the cerebellum as well as in medullary and pontine cerebellar projections. Cerebellar pathology was highly selective and severely involved subcortical white matter, whereas deep white matter and granular layer were only mildly affected and the molecular layer was spared. Loss of Purkinje cells increased with disease duration and was associated with neuronal and axonal abnormalities. Neocortex, basal ganglia and spinal cord became consecutively involved with the increasing burden of α-syn pathology, followed by hippocampus, amygdala, and, finally, the visual cortex. GCIs were associated with myelinated axons, and the severity of GCIs correlated with demyelination.

CONCLUSIONS

Our findings indicate that cerebellar subcortical white matter and cerebellar brainstem projections are likely the earliest foci of α-syn pathology in MSA-C, followed by involvement of more widespread regions of the central nervous system and neurodegeneration with disease progression.

The GAAIN Entity Mapper: An Active-Learning System for Medical Data Mapping

This work is focused on mapping biomedical datasets to a common representation, as an integral part of data harmonization for integrated biomedical data access and sharing. We present GEM, an intelligent software assistant for automated data mapping across different datasets or from a dataset to a common data model. The GEM system automates data mapping by providing precise suggestions for data element mappings. It leverages the detailed metadata about elements in associated dataset documentation such as data dictionaries that are typically available with biomedical datasets. It employs unsupervised text mining techniques to determine similarity between data elements and also employs machine-learning classifiers to identify element matches. It further provides an active-learning capability where the process of training the GEM system is optimized. Our experimental evaluations show that the GEM system provides highly accurate data mappings (over 90% accuracy) for real datasets of thousands of data elements each, in the Alzheimer's disease research domain. Further, the effort in training the system for new datasets is also optimized. We are currently employing the GEM system to map Alzheimer's disease datasets from around the globe into a common representation, as part of a global Alzheimer's disease integrated data sharing and analysis network called GAAIN. GEM achieves significantly higher data mapping accuracy for biomedical datasets compared to other state-of-the-art tools for database schema matching that have similar functionality. With the use of active-learning capabilities, the user effort in training the system is minimal.

Semi-Automated Digital Image Analysis of Pick's Disease and TDP-43 Proteinopathy

Digital image analysis of histology sections provides reliable, high-throughput methods for neuropathological studies but data is scant in frontotemporal lobar degeneration (FTLD), which has an added challenge of study due to morphologically diverse pathologies. Here, we describe a novel method of semi-automated digital image analysis in FTLD subtypes including: Pick's disease (PiD, n=11) with tau-positive intracellular inclusions and neuropil threads, and TDP-43 pathology type C (FTLD-TDPC, n=10), defined by TDP-43-positive aggregates predominantly in large dystrophic neurites. To do this, we examined three FTLD-associated cortical regions: mid-frontal gyrus (MFG), superior temporal gyrus (STG) and anterior cingulate gyrus (ACG) by immunohistochemistry. We used a color deconvolution process to isolate signal from the chromogen and applied both object detection and intensity thresholding algorithms to quantify pathological burden. We found object-detection algorithms had good agreement with gold-standard manual quantification of tau- and TDP-43-positive inclusions. Our sampling method was reliable across three separate investigators and we obtained similar results in a pilot analysis using open-source software. Regional comparisons using these algorithms finds differences in regional anatomic disease burden between PiD and FTLD-TDP not detected using traditional ordinal scale data, suggesting digital image analysis is a powerful tool for clinicopathological studies in morphologically diverse FTLD syndromes.

HDACiDB: a database for histone deacetylase inhibitors

An histone deacetylase (HDAC) inhibitor database (HDACiDB) was constructed to enable rapid access to data relevant to the development of epigenetic modulators (HDAC inhibitors [HDACi]), helping bring precision cancer medicine a step closer. Thousands of HDACi targeting HDACs are in various stages of development and are being tested in clinical trials as monotherapy and in combination with other cancer agents. Despite the abundance of HDACi, information resources are limited. Tools for in silico experiments on specific HDACi prediction, for designing and analyzing the generated data, as well as custom-made specific tools and interactive databases, are needed. We have developed an HDACiDB that is a composite collection of HDACi and currently comprises 1,445 chemical compounds, including 419 natural and 1,026 synthetic ones having the potential to inhibit histone deacetylation. Most importantly, it will allow application of Lipinski’s rule of five drug-likeness and other physicochemical property-based screening of the inhibitors. It also provides easy access to information on their source of origin, molecular properties, drug likeness, as well as bioavailability with relevant references cited. Being the first comprehensive database on HDACi that contains all known natural and synthetic HDACi, the HDACiDB may help to improve our knowledge concerning the mechanisms of actions of available HDACi and enable us to selectively target individual HDAC isoforms and establish a new paradigm for intelligent epigenetic cancer drug design. The database is freely available on the http://hdacidb.bioinfo.au-kbc.org.in/hdacidb/website.

How I do it: a practical database management system to assist clinical research teams with data collection, organization, and reporting

RATIONALE AND OBJECTIVES

The objective of this study was to demonstrate that an intra-arterial liver therapy clinical research database system is a more workflow efficient and robust tool for clinical research than a spreadsheet storage system. The database system could be used to generate clinical research study populations easily with custom search and retrieval criteria.

MATERIALS AND METHODS

A questionnaire was designed and distributed to 21 board-certified radiologists to assess current data storage problems and clinician reception to a database management system. Based on the questionnaire findings, a customized database and user interface system were created to perform automatic calculations of clinical scores including staging systems such as the Child-Pugh and Barcelona Clinic Liver Cancer, and facilitates data input and output.

RESULTS

Questionnaire participants were favorable to a database system. The interface retrieved study-relevant data accurately and effectively. The database effectively produced easy-to-read study-specific patient populations with custom-defined inclusion/exclusion criteria.

CONCLUSIONS

The database management system is workflow efficient and robust in retrieving, storing, and analyzing data.

Hypermethylation of repeat expanded C9orf72 is a clinical and molecular disease modifier

C9orf72 promoter hypermethylation inhibits the accumulation of pathologies which have been postulated to be neurotoxic. We tested here whether C9orf72 hypermethylation is associated with prolonged disease in C9orf72 mutation carriers. C9orf72 methylation was quantified from brain or blood using methylation-sensitive restriction enzyme digest-qPCR in a cross-sectional cohort of 118 C9orf72 repeat expansion carriers and 19 non-carrier family members. Multivariate regression models were used to determine whether C9orf72 hypermethylation was associated with age at onset, disease duration, age at death, or hexanucleotide repeat expansion size. Permutation analysis was performed to determine whether C9orf72 methylation is heritable. We observed a high correlation between C9orf72 methylation across tissues including cerebellum, frontal cortex, spinal cord and peripheral blood. While C9orf72 methylation was not significantly different between ALS and FTD and did not predict age at onset, brain and blood C9orf72 hypermethylation was associated with later age at death in FTD (brain: β = 0.18, p = 0.006; blood: β = 0.15, p < 0.001), and blood C9orf72 hypermethylation was associated with longer disease duration in FTD (β = 0.03, p = 0.007). Furthermore, C9orf72 hypermethylation was associated with smaller hexanucleotide repeat length (β = -16.69, p = 0.033). Finally, analysis of pedigrees with multiple mutation carriers demonstrated a significant association between C9orf72 methylation and family relatedness (p < 0.0001). C9orf72 hypermethylation is associated with prolonged disease in C9orf72 repeat expansion carriers with FTD. The attenuated clinical phenotype associated with C9orf72 hypermethylation suggests that slower clinical progression in FTD is associated with reduced expression of mutant C9orf72. These results support the hypothesis that expression of the hexanucleotide repeat expansion is associated with a toxic gain of function.

A comparison of Aβ amyloid pathology staging systems and correlation with clinical diagnosis

Current neuropathological Alzheimer's disease (AD) criteria from the National Institute on Aging-Alzheimer's Association (NIA-AA) incorporate two staging systems for Aβ pathology, namely the Thal Aβ phase (TAP) and the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) methods. The goal of this study was to compare and contrast results obtained with these two different staging systems for Aβ pathology since this is critical for future correlations of Aβ amyloid imaging data with Aβ neuropathology data based on immunohistochemical detection of Aβ deposits. A total of 123 cases, divided into 82 training and 41 validation cases, with a diagnosis of either unremarkable adult brain (normal) or AD and CERAD scores ranging from none to frequent were included. There was no clear and consistent relationship between CERAD and the TAP Aβ scores with the exception of scores for the highest plaque burdens (i.e., CERAD C3 and TAP A3) in the cases studied here. However, we developed an algorithm that relates CERAD scores to TAP scores with high agreement (94 % in training and 98 % in the validation set). In addition, TAP scores were a better predictor of dementia (sensitivity of 94 % specificity 87.7 %) than CERAD scores (sensitivity of 57 % specificity 100 %). Yet, further research is needed to define strategies to relate CERAD and TAP Aβ plaque scores to compare their utility and for determining the clinical associations of these different amyloid staging systems with aging and AD.

TDP-43 pathology and neuronal loss in amyotrophic lateral sclerosis spinal cord

We examined the phosphorylated 43-kDa TAR DNA-binding protein (pTDP-43) inclusions as well as neuronal loss in full-length spinal cords and five selected regions of the central nervous system from 36 patients with amyotrophic lateral sclerosis (ALS) and 10 age-matched normal controls. The most severe neuronal loss and pTDP-43 lesions were seen in lamina IX motor nuclei columns 4, 6, and 8 of lower cervical segments and in columns 9-11 of lumbosacral segments. Severity of pTDP-43 pathology and neuronal loss correlated closely with gray and white matter oligodendroglial involvement and was linked to onset of disease, with severe involvement of columns 4, 6, and 8 of upper extremity onset cases and severe involvement of columns of 9, 10, and 11 in cases with lower extremity onset. Severe TDP-43 lesions and neuronal loss were observed in stage 4 cases and sometimes included Onuf's nucleus. Notably, three cases displayed pTDP-43 aggregates in the midbrain oculomotor nucleus, which we had not seen previously even in cases with advanced (i.e., stage 4) pathology. pTDP-43 aggregates were observed in neurons of Clarke's column in 30.6 % of cases but rarely in the intermediolateral nucleus (IML). Gray matter oligodendroglial pTDP-43 inclusions were present in areas devoid of neuronal pTDP-43 aggregates and neuronal loss. Taken together, our findings indicate that (1) the dorsolateral motor nuclei columns of the cervical and lumbosacral anterior horn may be the earliest foci of pTDP-43 pathology in the spinal cord, (2) gray matter oligodendroglial involvement is an early event in the ALS disease process that possibly heralds subsequent involvement of neurons by pTDP-43 pathology, and (3) in some very advanced cases, there is oculomotor nucleus involvement, which may constitute an additional neuropathological stage (designated here as stage 5) of pTDP-43 pathology in ALS.

Sequential distribution of pTDP-43 pathology in behavioral variant frontotemporal dementia (bvFTD)

We examined regional distribution patterns of phosphorylated 43-kDa TAR DNA-binding protein (pTDP-43) intraneuronal inclusions in frontotemporal lobar degeneration (FTLD). Immunohistochemistry was performed on 70 μm sections from FTLD-TDP autopsy cases (n = 39) presenting with behavioral variant frontotemporal dementia. Two main types of cortical pTDP-43 pathology emerged, characterized by either predominantly perikaryal pTDP-43 inclusions (cytoplasmic type, cFTLD) or long aggregates in dendrites (neuritic type, nFTLD). Cortical involvement in nFTLD was extensive and frequently reached occipital areas, whereas cases with cFTLD often involved bulbar somatomotor neurons and the spinal cord. We observed four patterns indicative of potentially sequential dissemination of pTDP-43: cases with the lowest burden of pathology (pattern I) were characterized by widespread pTDP-43 lesions in the orbital gyri, gyrus rectus, and amygdala. With increasing burden of pathology (pattern II) pTDP-43 lesions emerged in the middle frontal and anterior cingulate gyrus as well as in anteromedial temporal lobe areas, the superior and medial temporal gyri, striatum, red nucleus, thalamus, and precerebellar nuclei. More advanced cases showed a third pattern (III) with involvement of the motor cortex, bulbar somatomotor neurons, and the spinal cord anterior horn, whereas cases with the highest burden of pathology (pattern IV) were characterized by pTDP-43 lesions in the visual cortex. We interpret the four neuropathological patterns in bvFTD to be consistent with the hypothesis that pTDP-43 pathology can spread sequentially and may propagate along axonal pathways.

TMEM106B is a genetic modifier of frontotemporal lobar degeneration with C9orf72 hexanucleotide repeat expansions

Hexanucleotide repeat expansions in chromosome 9 open reading frame 72 (C9orf72) have recently been linked to frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis, and may be the most common genetic cause of both neurodegenerative diseases. Genetic variants at TMEM106B influence risk for the most common neuropathological subtype of FTLD, characterized by inclusions of TAR DNA-binding protein of 43 kDa (FTLD-TDP). Previous reports have shown that TMEM106B is a genetic modifier of FTLD-TDP caused by progranulin (GRN) mutations, with the major (risk) allele of rs1990622 associating with earlier age at onset of disease. Here, we report that rs1990622 genotype affects age at death in a single-site discovery cohort of FTLD patients with C9orf72 expansions (n = 14), with the major allele correlated with later age at death (p = 0.024). We replicate this modifier effect in a 30-site international neuropathological cohort of FTLD-TDP patients with C9orf72 expansions (n = 75), again finding that the major allele associates with later age at death (p = 0.016), as well as later age at onset (p = 0.019). In contrast, TMEM106B genotype does not affect age at onset or death in 241 FTLD-TDP cases negative for GRN mutations or C9orf72 expansions. Thus, TMEM106B is a genetic modifier of FTLD with C9orf72 expansions. Intriguingly, the genotype that confers increased risk for developing FTLD-TDP (major, or T, allele of rs1990622) is associated with later age at onset and death in C9orf72 expansion carriers, providing an example of sign epistasis in human neurodegenerative disease.

Acetylated tau neuropathology in sporadic and hereditary tauopathies

We have recently shown acetylation of tau at lysine residue 280 (AC-K280) to be a disease-specific modification in Alzheimer disease (AD), corticobasal degeneration, and progressive supranuclear palsy, likely representing a major regulatory tau modification. Herein, we extend our observations using IHC with a polyclonal antibody specific for AC-K280. Thirty brain regions were examined in argyrophilic grain disease (AGD; n = 5), tangle-predominant senile dementia (TPSD; n = 5), Pick disease (n = 4), familial AD (FAD; n = 2; PSEN1 p.G206A and p.S170P), and frontotemporal dementia with parkinsonism linked to chromosome-17 (FTDP-17; n = 2; MAPT p.P301L and IVS10 + 16). All AGD, TPSD, FAD, and FTDP-17 cases had significant AC-K280 reactivity that was similar in severity and distribution to phosphorylated tau. AC-K280 robustly labeled grain pathological characteristics in AGD and was predominantly associated with thioflavin-S-positive neurofibrillary tangles and less reactive in neuropil threads and extracellular tangles in TPSD and FAD. Thioflavin-S-negative neuronal and glial inclusions of patients with FTDP-17 were robustly AC-K280 reactive. A low degree of AC-K280 was found in a subset of 4-repeat tau-containing lesions in Pick disease. AC-K280 is a prominent feature of both neuronal and glial tau aggregations in tauopathies of various etiologies. The close association of AC-K280 with amyloid and pre-amyloid conformations of tau suggests a potential role in tangle maturation and, thus, could serve as a useful biomarker or therapeutic target in a variety of tauopathies.

A platform for discovery: The University of Pennsylvania Integrated Neurodegenerative Disease Biobank

Neurodegenerative diseases (NDs) are defined by the accumulation of abnormal protein deposits in the central nervous system (CNS), and only neuropathological examination enables a definitive diagnosis. Brain banks and their associated scientific programs have shaped the actual knowledge of NDs, identifying and characterizing the CNS deposits that define new diseases, formulating staging schemes, and establishing correlations between neuropathological changes and clinical features. However, brain banks have evolved to accommodate the banking of biofluids as well as DNA and RNA samples. Moreover, the value of biobanks is greatly enhanced if they link all the multidimensional clinical and laboratory information of each case, which is accomplished, optimally, using systematic and standardized operating procedures, and in the framework of multidisciplinary teams with the support of a flexible and user-friendly database system that facilitates the sharing of information of all the teams in the network. We describe a biobanking system that is a platform for discovery research at the Center for Neurodegenerative Disease Research at the University of Pennsylvania.

The unfolded protein response is activated in disease-affected brain regions in progressive supranuclear palsy and Alzheimer's disease

Background

Progressive supranuclear palsy (PSP) is a neurodegenerative disorder pathologically characterized by intracellular tangles of hyperphosphorylated tau protein distributed throughout the neocortex, basal ganglia, and brainstem. A genome-wide association study identified EIF2AK3 as a risk factor for PSP. EIF2AK3 encodes PERK, part of the endoplasmic reticulum’s (ER) unfolded protein response (UPR). PERK is an ER membrane protein that senses unfolded protein accumulation within the ER lumen. Recently, several groups noted UPR activation in Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis, multiple system atrophy, and in the hippocampus and substantia nigra of PSP subjects. Here, we evaluate UPR PERK activation in the pons, medulla, midbrain, hippocampus, frontal cortex and cerebellum in subjects with PSP, AD, and in normal controls.

Results

We found UPR activation primarily in disease-affected brain regions in both disorders. In PSP, the UPR was primarily activated in the pons and medulla and to a much lesser extent in the hippocampus. In AD, the UPR was extensively activated in the hippocampus. We also observed UPR activation in the hippocampus of some elderly normal controls, severity of which positively correlated with both age and tau pathology but not with Aβ plaque burden. Finally, we evaluated EIF2AK3 coding variants that influence PERK activation. We show that a haplotype associated with increased PERK activation is genetically associated with increased PSP risk.

Conclusions

The UPR is activated in disease affected regions in PSP and the genetic evidence shows that this activation increases risk for PSP and is not a protective response.

Stages of pTDP-43 pathology in amyotrophic lateral sclerosis

OBJECTIVE

To see whether the distribution patterns of phosphorylated 43kDa TAR DNA-binding protein (pTDP-43) intraneuronal inclusions in amyotrophic lateral sclerosis (ALS) permit recognition of neuropathological stages.

METHODS

pTDP-43 immunohistochemistry was performed on 70 μm sections from ALS autopsy cases (N = 76) classified by clinical phenotype and genetic background.

RESULTS

ALS cases with the lowest burden of pTDP-43 pathology were characterized by lesions in the agranular motor cortex, brainstem motor nuclei of cranial nerves V, VII, and X-XII, and spinal cord α-motoneurons (stage 1). Increasing burdens of pathology showed involvement of the prefrontal neocortex (middle frontal gyrus), brainstem reticular formation, precerebellar nuclei, and the red nucleus (stage 2). In stage 3, pTDP-43 pathology involved the prefrontal (gyrus rectus and orbital gyri) and then postcentral neocortex and striatum. Cases with the greatest burden of pTDP-43 lesions showed pTDP-43 inclusions in anteromedial portions of the temporal lobe, including the hippocampus (stage 4). At all stages, these lesions were accompanied by pTDP-43 oligodendroglial aggregates. Ten cases with C9orf72 repeat expansion displayed the same sequential spreading pattern as nonexpansion cases but a greater regional burden of lesions, indicating a more fulminant dissemination of pTDP-43 pathology.

INTERPRETATION

pTDP-43 pathology in ALS possibly disseminates in a sequential pattern that permits recognition of 4 neuropathological stages consistent with the hypothesis that pTDP-43 pathology is propagated along axonal pathways. Moreover, the finding that pTDP-43 pathology develops in the prefrontal cortex as part of an ongoing disease process could account for the development of executive cognitive deficits in ALS.