Genetic and Clinical Correlates of AI-Based Brain Aging Patterns in Cognitively Unimpaired Individuals

Importance

Brain aging elicits complex neuroanatomical changes influenced by multiple age-related pathologies. Understanding the heterogeneity of structural brain changes in aging may provide insights into preclinical stages of neurodegenerative diseases.

Objective

To derive subgroups with common patterns of variation in participants without diagnosed cognitive impairment (WODCI) in a data-driven manner and relate them to genetics, biomedical measures, and cognitive decline trajectories.

Design, Setting, and Participants

Data acquisition for this cohort study was performed from 1999 to 2020. Data consolidation and harmonization were conducted from July 2017 to July 2021. Age-specific subgroups of structural brain measures were modeled in 4 decade-long intervals spanning ages 45 to 85 years using a deep learning, semisupervised clustering method leveraging generative adversarial networks. Data were analyzed from July 2021 to February 2023 and were drawn from the Imaging-Based Coordinate System for Aging and Neurodegenerative Diseases (iSTAGING) international consortium. Individuals WODCI at baseline spanning ages 45 to 85 years were included, with greater than 50 000 data time points.

Exposures

Individuals WODCI at baseline scan.

Main Outcomes and Measures

Three subgroups, consistent across decades, were identified within the WODCI population. Associations with genetics, cardiovascular risk factors (CVRFs), amyloid β (Aβ), and future cognitive decline were assessed.

Results

In a sample of 27 402 individuals (mean [SD] age, 63.0 [8.3] years; 15 146 female [55%]) WODCI, 3 subgroups were identified in contrast with the reference group: a typical aging subgroup, A1, with a specific pattern of modest atrophy and white matter hyperintensity (WMH) load, and 2 accelerated aging subgroups, A2 and A3, with characteristics that were more distinct at age 65 years and older. A2 was associated with hypertension, WMH, and vascular disease-related genetic variants and was enriched for Aβ positivity (ages ≥65 years) and apolipoprotein E (APOE) ε4 carriers. A3 showed severe, widespread atrophy, moderate presence of CVRFs, and greater cognitive decline. Genetic variants associated with A1 were protective for WMH (rs7209235: mean [SD] B = -0.07 [0.01]; P value = 2.31 × 10-9) and Alzheimer disease (rs72932727: mean [SD] B = 0.1 [0.02]; P value = 6.49 × 10-9), whereas the converse was observed for A2 (rs7209235: mean [SD] B = 0.1 [0.01]; P value = 1.73 × 10-15 and rs72932727: mean [SD] B = -0.09 [0.02]; P value = 4.05 × 10-7, respectively); variants in A3 were associated with regional atrophy (rs167684: mean [SD] B = 0.08 [0.01]; P value = 7.22 × 10-12) and white matter integrity measures (rs1636250: mean [SD] B = 0.06 [0.01]; P value = 4.90 × 10-7).

Conclusions and Relevance

The 3 subgroups showed distinct associations with CVRFs, genetics, and subsequent cognitive decline. These subgroups likely reflect multiple underlying neuropathologic processes and affect susceptibility to Alzheimer disease, paving pathways toward patient stratification at early asymptomatic stages and promoting precision medicine in clinical trials and health care.

Relationships of Cognitive Measures with Cerebrospinal Fluid but Not Imaging Biomarkers of Alzheimer Disease Vary between Black and White Individuals

OBJECTIVE

Biomarkers of Alzheimer disease vary between groups of self-identified Black and White individuals in some studies. This study examined whether the relationships between biomarkers or between biomarkers and cognitive measures varied by racialized groups.

METHODS

Cerebrospinal fluid (CSF), amyloid positron emission tomography (PET), and magnetic resonance imaging measures were harmonized across four studies of memory and aging. Spearman correlations between biomarkers and between biomarkers and cognitive measures were calculated within each racialized group, then compared between groups by standard normal tests after Fisher's Z-transformations.

RESULTS

The harmonized dataset included at least one biomarker measurement from 495 Black and 2,600 White participants. The mean age was similar between racialized groups. However, Black participants were less likely to have cognitive impairment (28% vs 36%) and had less abnormality of some CSF biomarkers including CSF Aβ42/40, total tau, p-tau181, and neurofilament light. CSF Aβ42/40 was negatively correlated with total tau and p-tau181 in both groups, but at a smaller magnitude in Black individuals. CSF Aβ42/40, total tau, and p-tau181 had weaker correlations with cognitive measures, especially episodic memory, in Black than White participants. Correlations of amyloid measures between CSF (Aβ42/40, Aβ42) and PET imaging were also weaker in Black than White participants. Importantly, no differences based on race were found in correlations between different imaging biomarkers, or in correlations between imaging biomarkers and cognitive measures.

INTERPRETATION

Relationships between CSF biomarkers but not imaging biomarkers varied by racialized groups. Imaging biomarkers performed more consistently across racialized groups in associations with cognitive measures. ANN NEUROL 2024;95:495-506.

Correlational analyses of biomarkers that are harmonized through a bridging study due to measurement errors

Evaluating correlations between disease biomarkers and clinical outcomes is crucial in biomedical research. During the early stages of many chronic diseases, changes in biomarkers and clinical outcomes are often subtle. A major challenge to detecting subtle correlations is that studies with large sample sizes are usually needed to achieve sufficient statistical power. This challenge is even greater when biofluid and imaging biomarker data are used because the required procedures are burdensome, perceived as invasive, and/or expensive, limiting sample sizes in individual studies. Combining data across multiple studies may increase statistical power, but biomarker data may be generated using different assay platforms, scanner types, or processing protocols, which may affect measured biomarker values. Therefore, harmonizing biomarker data is essential to combining data across studies. Bridging studies involve re-processing of a subset of samples or imaging scans to evaluate how biomarker values vary by studies. This presents an analytic challenge on how to best harmonize biomarker data across studies to allow unbiased and optimal estimates of their correlations with standardized clinical outcomes. We conceptualize that a latent biomarker underlies the observed biomarkers across studies, and propose a novel approach that integrates the data in the bridging study with the study-specific biomarker data for estimating the biological correlations between biomarkers and clinical outcomes. Through extensive simulations, we compare our method to several alternative methods/algorithms often used to estimate the correlations. Finally, we demonstrate the application of this methodology to a real-world multi-center Alzheimer's disease biomarker study to correlate cerebrospinal fluid biomarker concentrations with cognitive outcomes.

Baseline levels and longitudinal rates of change in plasma Aβ42/40 among self-identified Black/African American and White individuals

Objective

The use of blood-based biomarkers of Alzheimer disease (AD) may facilitate access to biomarker testing of groups that have been historically under-represented in research. We evaluated whether plasma Aβ42/40 has similar or different baseline levels and longitudinal rates of change in participants racialized as Black or White.

Methods

The Study of Race to Understand Alzheimer Biomarkers (SORTOUT-AB) is a multi-center longitudinal study to evaluate for potential differences in AD biomarkers between individuals racialized as Black or White. Plasma samples collected at three AD Research Centers (Washington University, University of Pennsylvania, and University of Alabama-Birmingham) underwent analysis with C2N Diagnostics' PrecivityAD™ blood test for Aβ42 and Aβ40. General linear mixed effects models were used to estimate the baseline levels and rates of longitudinal change for plasma Aβ measures in both racial groups. Analyses also examined whether dementia status, age, sex, education, APOE ε4 carrier status, medical comorbidities, or fasting status modified potential racial differences.

Results

Of the 324 Black and 1,547 White participants, there were 158 Black and 759 White participants with plasma Aβ measures from at least two longitudinal samples over a mean interval of 6.62 years. At baseline, the group of Black participants had lower levels of plasma Aβ40 but similar levels of plasma Aβ42 as compared to the group of White participants. As a result, baseline plasma Aβ42/40 levels were higher in the Black group than the White group, consistent with the Black group having lower levels of amyloid pathology. Racial differences in plasma Aβ42/40 were not modified by age, sex, education, APOE ε4 carrier status, medical conditions (hypertension and diabetes), or fasting status. Despite differences in baseline levels, the Black and White groups had a similar longitudinal rate of change in plasma Aβ42/40.

Interpretation

Black individuals participating in AD research studies had a higher mean level of plasma Aβ42/40, consistent with a lower level of amyloid pathology, which, if confirmed, may imply a lower proportion of Black individuals being eligible for AD clinical trials in which the presence of amyloid is a prerequisite. However, there was no significant racial difference in the rate of change in plasma Aβ42/40, suggesting that amyloid pathology accumulates similarly across racialized groups.

Genomic loci influence patterns of structural covariance in the human brain

Normal and pathologic neurobiological processes influence brain morphology in coordinated ways that give rise to patterns of structural covariance (PSC) across brain regions and individuals during brain aging and diseases. The genetic underpinnings of these patterns remain largely unknown. We apply a stochastic multivariate factorization method to a diverse population of 50,699 individuals (12 studies and 130 sites) and derive data-driven, multi-scale PSCs of regional brain size. PSCs were significantly correlated with 915 genomic loci in the discovery set, 617 of which are newly identified, and 72% were independently replicated. Key pathways influencing PSCs involve reelin signaling, apoptosis, neurogenesis, and appendage development, while pathways of breast cancer indicate potential interplays between brain metastasis and PSCs associated with neurodegeneration and dementia. Using support vector machines, multi-scale PSCs effectively derive imaging signatures of several brain diseases. Our results elucidate genetic and biological underpinnings that influence structural covariance patterns in the human brain.

Alzheimer Disease Biomarkers: Moving from CSF to Plasma for Reliable Detection of Amyloid and tau Pathology

BACKGROUND

Development of validated biomarkers to detect early Alzheimer disease (AD) neuropathology is needed for therapeutic AD trials. Abnormal concentrations of "core" AD biomarkers, cerebrospinal fluid (CSF) amyloid beta1-42, total tau, and phosphorylated tau correlate well with neuroimaging biomarkers and autopsy findings. Nevertheless, given the limitations of established CSF and neuroimaging biomarkers, accelerated development of blood-based AD biomarkers is underway.

CONTENT

Here we describe the clinical significance of CSF and plasma AD biomarkers to detect disease pathology throughout the Alzheimer continuum and correlate with imaging biomarkers. Use of the AT(N) classification by CSF and imaging biomarkers provides a more objective biologically based diagnosis of AD than clinical diagnosis alone. Significant progress in measuring CSF AD biomarkers using extensively validated highly automated assay systems has facilitated their transition from research use only to approved in vitro diagnostics tests for clinical use. We summarize development of plasma AD biomarkers as screening tools for enrollment and monitoring participants in therapeutic trials and ultimately in clinical care. Finally, we discuss the challenges for AD biomarkers use in clinical trials and precision medicine, emphasizing the possible ethnocultural differences in the levels of AD biomarkers.

SUMMARY

CSF AD biomarker measurements using fully automated analytical platforms is possible. Building on this experience, validated blood-based biomarker tests are being implemented on highly automated immunoassay and mass spectrometry platforms. The progress made developing analytically and clinically validated plasma AD biomarkers within the AT(N) classification scheme can accelerate use of AD biomarkers in therapeutic trials and routine clinical practice.

A - 06 Sensitivity of Remote App-Based Assessment of Cognition among Older Adults to Fatigue-Mediated Differences in Cognitive Functioning

OBJECTIVE

This study assesses the sensitivity of the mobile cognitive app performance platform (mCAPP), a mobile and engaging cognitive assessment tool, to participant reported fatigue.

METHOD

The mCAPP includes three gamified tasks: a memory task ("Concentration"), a stroop-like task ("Brick Drop"), and a digit-symbol coding-like task ("Space Imposters"). For all games, shorter reaction times and fewer guesses indicate better performance. The cohort included 55 participants (72.73% female; age = 71.60 ± 4.48; education = 16.71 ± 2.30; 49.1% white; 49.1% Black/African American, 1.8% Multiracial) without cognitive impairment who are enrolled in the Penn ADRC cohort. Performance was analyzed as a whole and grouped into days of high (7+) and low (0-3) fatigue (range 0-10).

RESULTS

The average fatigue rating was 2.61 ± 2.51. Overall, higher reported fatigue was weakly correlated with more time spent (ρ = 0.22) and a higher number of guesses on Concentration (ρ = 0.12; p-values<0.01). There was a significant difference in speed for those with high fatigue (M = 2.825) and low fatigue (M = 2.592; p = 0.018) on Space Imposters, but not on Brick Drop (p = 0.15). On Concentration, those with high fatigue needed a higher number of guesses (M = 5.356) compared to low fatigue (M = 5.095; p = 0.003) and more time was spent on individual guesses for those with high fatigue (M = 17.587) compared to low fatigue (M = 13.357; p < 0.001).

CONCLUSION

The mCAPP can remotely detect differences in cognitive performance in self-reported high and low fatigue states. Future studies will include looking at sleep data to determine objective measures of fatigue-related behavior and in-depth analysis of performance within-subject.

A - 02 Performance and Usage of a Remote App-Based Cognitive Assessment among Older Adults with a Range of Technology Experience

OBJECTIVE

The mobile cognitive app performance platform (mCAPP), an app-based cognitive assessment, includes memory and executive functioning tasks to remotely detect cognitive changes associated with aging and preclinical Alzheimer's disease. This study examines the relationship between prior experience and comfort with mobile technology and subjective experiences with mCAPP.

METHOD

60 older adults (73% female; age = 74 ± 4.8; education = 17 ± 2.4 years; 48% Black/African American) with normal cognition enrolled in the Penn Alzheimer's Disease Research Center cohort completed one baseline session and two weeks of at-home mCAPP use. This study included measures of prior experience with mobile technology and games, at-home mCAPP performance and usage levels, and feedback on mCAPP usability.

RESULTS

62% of participants reported using mobile devices to play games ("game-players"), and they did not differ from non-users in age or global cognitive status. Game-players self-reported significantly higher proficiency with specific mobile technology features (p = 0.028), but not perceived independence or confidence with technology. mCAPP performance differences were present at baseline but not by the 8th at-home session. Usability and enjoyment of mCAPP were high and increased for both groups. Non-players reported lower likelihood to play mCAPP games at baseline (p < 0.05), but in practice increased play frequency throughout at-home use and reported higher likelihood to play mCAPP games afterwards (p ≤ 0.001).

CONCLUSION (S)

Participants with varying mobile game experience-levels were willing and able to use mCAPP at-home. Both groups found mCAPP easy and enjoyable to use, and non-players particularly showed increased adoption of mCAPP. This pilot study shows preliminary feasibility of mobile app-based assessment regardless of prior experience with mobile games.

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.

Pathological combinations in neurodegenerative disease are heterogeneous and disease-associated

Pathologies that are causative for neurodegenerative disease (ND) are also frequently present in unimpaired, older individuals. In this retrospective study of 1,647 autopsied individuals, we report the incidence of ten pathologies across ND and normal ageing in attempt to clarify which pathological combinations are disease-associated and which are ageing-related. Eight clinically defined groups were examined including unimpaired individuals and those with clinical Alzheimer's disease, mixed dementia, amyotrophic lateral sclerosis, frontotemporal degeneration, multiple system atrophy, probable Lewy body disease, or probable tauopathies. Up to seven pathologies were observed concurrently resulting in a heterogenous mix of 161 pathological combinations. The presence of multiple, additive pathologies associated with older age, increasing disease duration, APOE e4 allele, and presence of dementia across the clinical groups. 15-67 combinations occurred in each group with the unimpaired group defined by 35 combinations. Most combinations occurred at a < 5% prevalence included 86 that were present in only 1-2 individuals. To better understand this heterogeneity, we organized the pathologic combinations into five broad categories based on their age-related frequency: 1) Ageing only for the unimpaired group combinations, 2) ND only if only the expected pathology for that individual's clinical phenotype was present, 3) Other ND if the expected pathology was not present, 4) ND + ageing if the expected pathology was present together with aging-related pathologies at a similar prevalence as the unimpaired group, and 5) ND + associated if the expected pathology was present together with other pathologies either not observed in the unimpaired group or observed at a greater frequency. ND only cases comprised a minority of cases (19-45%) except in the amyotrophic lateral sclerosis (56%) and multiple system atrophy (65%) groups. The ND + ageing category represented 9-28% of each group, but was rare in Alzheimer's disease (1%). ND + associated combinations were common in Alzheimer's disease (58%) and Lewy body disease (37%) and were observed in all groups. The Ageing only and Other ND categories accounted for a minority of individuals in each group. This observed heterogeneity indicates that the total pathological burden in ND is frequently more than a primary expected clinicopathological correlation with a high frequency of additional disease- or age-associated pathologies.

Testing for Alzheimer Disease Biomarkers and Disclosing Results Across the Disease Continuum

Three pathological processes define or are characteristic of Alzheimer's disease (AD): amyloid-β, hyperphosphorylated tau, and neurodegeneration. Our understanding of AD is undergoing a transformation due to our ability to measure biomarkers of these processes across different stages of cognitive impairment. There is growing interest in using AD biomarker tests in care and research and, with this, a growing need for guidance on how to return these sensitive results to patients and participants. Here, we propose a five-step approach informed by: clinical and research experience designing and implementing AD biomarker disclosure processes; extant evidence describing how individuals react to AD biomarker information; ethics; and the literature on breaking bad news. The clinician should (1) determine the appropriateness of AD biomarker testing and return of results for the particular patient or research participant. If testing is appropriate, the next steps are to: (2) provide pre-test education and seek consent for testing to the individual and their support person; (3) administer testing; (4) return the results to the individual and their support person; and (5) follow up to promote the recipient's wellbeing and to learn from their experience. We conclude by identifying open questions to guide future studies of biomarker disclosure.

SHORT TELOMERES ASSOCIATE WITH HYPERPHOSPHORYLATED TAU BURDEN IN PRIMARY AGE-RELATED TAUOPATHY

Aging is a major risk factor for hyperphosphorylated tau burden (p-tau). Telomeres lengths (TL) shorten with age and various sources of DNA damage, thus provide a measure of biological age. Additionally, DNA methylation (DNAm) changes over time and may contribute to changes in TL. We hypothesize that shorter TL will be associated with increased risk of p-tau burden and that this process may be mediated by DNAm. We extracted DNA from frontal cortex of 113 individuals (Age=87.3 + 9.3; 37% Female) that met neuropathological criteria for primary age-related tauopathy (PART), characterized by p-tau in the absence of amyloid pathology. We measured mean TL using qPCR to determine the copy number of telomere repeat DNA in comparison to a single copy gene. We also measured DNA methylation using the Illumina MethylationEPIC Kit for ~850K CpGs. P-tau was measured in medial temporal cortex using an Aperio Digital Pathology Slide Scanner. Linear regression revealed that shorter TL was associated with increased p-tau burden (B=-0.28; p=-.003), including adjustment for age (B=0.003; p=0.003). eWAS identified six CpGs associated with TL (all q< 0.05). Causal mediation analyses identified that two of these CpGs mediate the TL and p-tau association: proportion mediated by cg08701686 (UNC5D) and cg24533059 (near IFNGR1 and OLIG3) was 32.5% and 48.6%, respectively. Shorter TL is associated with increased p-tau pathological burden in PART and may be mediated in part by DNAm at particular loci. These findings support the concept that biological aging, as measured with TL and DNAm, may contribute to tauopathy beyond chronological aging.

CSF Biomarkers of Alzheimer Disease in Patients With Concomitant α-Synuclein Pathology

BACKGROUND AND OBJECTIVES

CSF biomarkers β-amyloid 1-42 (Aβ42), phosphorylated tau 181 (p-tau181), total tau (t-tau), and neurogranin (Ng) can diagnose Alzheimer disease (AD) in life. However, it is unknown whether CSF concentrations, and thus their accuracies, are affected by concomitant pathologies common in AD, such as α-synuclein (αSyn). Our primary goal was to test whether biomarkers in patients with AD are altered by concomitant αSyn. We compared CSF Aβ42, p-tau181, t-tau, and Ng levels across autopsy-confirmed AD and concomitant AD and αSyn (AD + αSyn). Antemortem CSF levels were related to postmortem accumulations of αSyn. Finally, we tested how concommitant AD + αSyn affected the diagnostic accuracy of 2 CSF-based strategies: the amyloid/tau/neurodegeneration (ATN) framework and the t-tau/Aβ42 ratio.

METHODS

Inclusion criteria were neuropathologic diagnoses of AD, mixed AD + αSyn, and αSyn. A convenience sample of nonimpaired controls was selected with available CSF and a Mini-Mental State Examination (MMSE) ≥ 27. αSyn without AD and controls were included as reference groups. Analyses of covariance (ANCOVAs) tested planned comparisons were CSF Aβ42, p-tau181, t-tau, and Ng differences across AD and AD + αSyn. Linear models tested how biomarkers were altered by αSyn accumulation in AD, accounting for pathologic β-amyloid and tau. Receiver operating characteristic and area under the curve (AUC), including 95% CI, evaluated diagnostic accuracy.

RESULTS

Participants were 61 patients with AD, 39 patients with mixed AD + αSyn, 20 patients with αSyn, and 61 controls. AD had similar median age (73 [interquartile range {IQR} = 12] years), MMSE (23 [IQR = 9]), and sex distribution (male = 49%) compared with AD + αSyn age (70 [IQR = 13] years; p = 0.3), MMSE (25 [IQR = 9.5]; p = 0.19), and sex distribution (male = 69%; p = 0.077). ANCOVAs showed that AD + αSyn had lower p-tau181 (F(1,94) = 17, p < 2.6e-16), t-tau (F(1,93) = 11, p = 0.0004), and Ng levels (F(1,50) = 12, p = 0.0004) than AD; there was no difference in Aβ42 (p = 0.44). Models showed increasing αSyn related to lower p-tau181 (β = -0.26, SE = 0.092, p = 0.0065), t-tau (β = -0.19, SE = 0.092, p = 0.041), and Ng levels (β = -0.2, SE = 0.066, p = 0.0046); αSyn was not a significant factor for Aβ42 (p = 1). T-tau/Aβ42 had the highest accuracy when detecting AD, including mixed AD + αSyn cases (AUC = 0.95; CI 0.92-0.98).

DISCUSSION

Findings demonstrate that concomitant αSyn pathology in AD is associated with lower CSF p-tau181, t-tau, and Ng levels and can affect diagnostic accuracy in patients with AD.

Limited Diagnostic Utility of Alpha Defensin in the Diagnosis of Periprosthetic Joint Infection

Introduction/Objective

A key component of laboratory stewardship is appropriate test utilization. We evaluated the utility of alpha defensin (AD), a synovial fluid biomarker, in the diagnosis of periprosthetic joint infection (PJI). Since PJI remains a diagnostic challenge in the orthopedic community, the Musculoskeletal Infection Society (MSIS) created the PJI score, a point-based criteria to help risk stratify the likelihood of infection. The score includes AD, synovial fluid white blood cell count, synovial fluid percent neutrophils, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP). AD is a specialized test which adds substantial cost to the evaluation of PJI .The purpose of this study was to investigate the diagnostic utility of the PJI score with AD and without AD (routine laboratory testing of serum and synovial fluid).

Methods/Case Report

Retrospective chart review was completed on 222 patients with suspected PJI identified at Geisinger Health between January 2019 – March 2021. Data was retrieved through Geisinger’s Phenomic and Analytics Data Core and imported into Excel and JMP v.12 for analysis. All available components of MSIS diagnostic criteria were collected for each patient.

Results (if a Case Study enter NA)

Of the 222 patients with AD testing, 81% of results were negative (n=178) and 19% results were positive (n=44). AD results corresponded with synovial fluid white blood cell count in 96 % of patients (213/ 222). All components of the PJI diagnostic criteria were collected in 69% of the patients (157/222). Diagnostic criteria calculated without AD showed 43% infected (68/157), 37% possibly infected (58/157), and 20% infected (31/157). Diagnostic criteria calculated with AD showed 43% infected (68/157), 35% possible infected (55/157), and 22% infected (34/157). PJI score including AD compared to PJI score excluding AD showed similar correlation (R2 = 0.93).

Conclusion

It was found that AD testing does not provide substantial diagnostic value in the evaluation of PJI. Synovial fluid cell count was found to directly correlate with alpha defensin suggesting it’s potential use as a surrogate marker for clinical decision making. Diagnostic criteria obtained through routine testing of serum (ESR, CRP) and synovial fluid (WBC, percent neutrophils) provides sufficient data for diagnosis.

Natural speech markers of Alzheimer's disease co-pathology in Lewy body dementias

INTRODUCTION

An estimated 50% of patients with Lewy body dementias (LBD), including Parkinson's disease dementia (PDD) and Dementia with Lewy bodies (DLB), have co-occurring Alzheimer's disease (AD) that is associated with worse prognosis. This study tests an automated analysis of natural speech as an inexpensive, non-invasive screening tool for AD co-pathology in biologically-confirmed cohorts of LBD patients with AD co-pathology (SYN + AD) and without (SYN-AD).

METHODS

We analyzed lexical-semantic and acoustic features of picture descriptions using automated methods in 22 SYN + AD and 38 SYN-AD patients stratified using AD CSF biomarkers or autopsy diagnosis. Speech markers of AD co-pathology were identified using best subset regression, and their diagnostic discrimination was tested using receiver operating characteristic. ANCOVAs compared measures between groups covarying for demographic differences and cognitive disease severity. We tested relations with CSF tau levels, and compared speech measures between PDD and DLB clinical disorders in the same cohort.

RESULTS

Age of acquisition of nouns (p = 0.034, |d| = 0.77) and lexical density (p = 0.0064, |d| = 0.72) were reduced in SYN + AD, and together showed excellent discrimination for SYN + AD vs. SYN-AD (95% sensitivity, 66% specificity; AUC = 0.82). Lower lexical density was related to higher CSF t-Tau levels (R = -0.41, p = 0.0021). Clinically-diagnosed PDD vs. DLB did not differ on any speech features.

CONCLUSION

AD co-pathology may result in a deviant natural speech profile in LBD characterized by specific lexical-semantic impairments, not detectable by clinical disorder diagnosis. Our study demonstrates the potential of automated digital speech analytics as a screening tool for underlying AD co-pathology in LBD.

Multimarker synaptic protein cerebrospinal fluid panels reflect TDP-43 pathology and cognitive performance in a pathological cohort of frontotemporal lobar degeneration

Background

Synapse degeneration is an early event in pathological frontotemporal lobar degeneration (FTLD). Consequently, a surrogate marker of synapse loss could be used to monitor early pathologic changes in patients with underlying FTLD. The aim of this study was to evaluate the relationship of antemortem cerebrospinal fluid (CSF) levels of 8 synaptic proteins with postmortem global tau and TDP-43 burden and cognitive performance and to assess their diagnostic capacity in a neuropathological FTLD cohort.

Methods

We included patients with a neuropathological confirmation of FTLD-Tau (n = 24, mean age-at-CSF 67 years ± 11), FTLD-TDP (n = 25, 66 years ± 9) or AD (n = 25, 73 years ± 6) as well as cognitively normal controls (n = 35, 69 years ± 7) from the Penn FTD Center and ADRC. We used a semi-quantitative measure of tau and TDP-43 inclusions to quantify pathological burden across 16 brain regions. Statistical methods included Spearman rank correlations, one-way analysis of covariance, ordinal regression, step-wise multiple linear regression and receiver-operating characteristic curves.

Result

CSF calsyntenin-1 and neurexin-2a were correlated in all patient groups (r_s = .55 to .88). In FTLD-TDP, we observed low antemortem CSF levels of calsyntenin-1 and neurexin-2a compared to AD (.72-fold, p = .001, .77-fold, p = .04, respectively) and controls (.80-fold, p = .02, .78-fold, p = .02, respectively), which were inversely associated with post-mortem global TDP-43 burden (regression r² = .56, p = .007 and r² = .57, p = .006, respectively). A multimarker panel including calsyntenin-1 was associated with TDP-43 burden (r² = .69, p = .003) and MMSE score (r² = .19, p = .03) in FTLD. A second multimarker synaptic panel, also including calsyntenin-1, was associated with MMSE score in FTLD-tau (r² = .49, p = .04) and improved diagnostic performance to discriminate FTLD-Tau and FTLD-TDP neuropathologic subtypes (AUC = .83).

Conclusion

These synaptic panels have potential in the differential diagnosis of FTLD neuropathologic subtypes and as surrogate markers of cognitive performance in future clinical trials targeting TDP-43 or tau.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13024-022-00534-y.

Predicted disconnectome associated with progressive periventricular white matter ischemia

We used a virtual lesion DTI fiber tracking approach with healthy subject DTI data and simulated periventricular white matter (PVWM) lesion masks to predict the sequence of connectivity changes associated with progressive PVWM ischemia. We found that the optic radiations, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, corpus callosum, temporopontine tract and fornix were affected in early simulated ischemic injury, and that the connectivity of subcortical, cerebellar, and visual regions were significantly disrupted with increasing simulated lesion severity. The results of this study provide insights into the spatial-temporal changes of the brain structural connectome under progressive PVWM ischemia. The virtual lesion approach provides a meaningful proxy to the spatial-temporal changes of the brain's structural connectome and can be used to further characterize the cognitive sequelae of progressive PVWM ischemia in both normal aging and dementia.

The development and convergence of co-pathologies in Alzheimer's disease

Cerebral amyloid angiopathy (CAA), limbic-predominant age-related TDP-43 encephalopathy neuropathological change (LATE-NC) and Lewy bodies occur in the absence of clinical and neuropathological Alzheimer's disease, but their prevalence and severity dramatically increase in Alzheimer's disease. To investigate how plaques, tangles, age and apolipoprotein E ε4 (APOE ε4) interact with co-pathologies in Alzheimer's disease, we analysed 522 participants ≥50 years of age with and without dementia from the Center for Neurodegenerative Disease Research (CNDR) autopsy program and 1340 participants in the National Alzheimer's Coordinating Center (NACC) database. Consensus criteria were applied for Alzheimer's disease using amyloid phase and Braak stage. Co-pathology was staged for CAA (neocortical, allocortical, and subcortical), LATE-NC (amygdala, hippocampal, and cortical), and Lewy bodies (brainstem, limbic, neocortical, and amygdala predominant). APOE genotype was determined for all CNDR participants. Ordinal logistic regression was performed to quantify the effect of independent variables on the odds of having a higher stage after checking the proportional odds assumption. We found that without dementia, increasing age associated with all pathologies including CAA (odds ratio 1.63, 95% confidence interval 1.38-1.94, P < 0.01), LATE-NC (1.48, 1.16-1.88, P < 0.01), and Lewy bodies (1.45, 1.15-1.83, P < 0.01), but APOE ε4 only associated with CAA (4.80, 2.16-10.68, P < 0.01). With dementia, increasing age associated with LATE-NC (1.30, 1.15-1.46, P < 0.01), while Lewy bodies associated with younger ages (0.90, 0.81-1.00, P = 0.04), and APOE ε4 only associated with CAA (2.36, 1.52-3.65, P < 0.01). A longer disease course only associated with LATE-NC (1.06, 1.01-1.11, P = 0.01). Dementia in the NACC cohort associated with the second and third stages of CAA (2.23, 1.50-3.30, P < 0.01), LATE-NC (5.24, 3.11-8.83, P < 0.01), and Lewy bodies (2.41, 1.51-3.84, P < 0.01). Pathologically, increased Braak stage associated with CAA (5.07, 2.77-9.28, P < 0.01), LATE-NC (5.54, 2.33-13.15, P < 0.01), and Lewy bodies (4.76, 2.07-10.95, P < 0.01). Increased amyloid phase associated with CAA (2.27, 1.07-4.80, P = 0.03) and Lewy bodies (6.09, 1.66-22.33, P = 0.01). In summary, we describe widespread distributions of CAA, LATE-NC and Lewy bodies that progressively accumulate alongside plaques and tangles in Alzheimer's disease dementia. CAA interacted with plaques and tangles especially in APOE ε4 positive individuals; LATE-NC associated with tangles later in the disease course; most Lewy bodies associated with moderate to severe plaques and tangles.

Detection of Alzheimer’s Disease-Related Cognitive Change With the Mobile Cognitive App Performance Platform

This study investigates the psychometric properties of the mobile cognitive app performance platform (mCAPP), designed to detect memory changes associated with preclinical Alzheimer’s Disease (AD). The mCAPP memory task includes learning and matching hidden card pairs and incorporates increasing memory load, pattern separation features, and spatial memory. Participants included 30 older adults with normal cognition. They completed the mCAPP, paper and pencil neuropsychological tests and a subset completed a high-resolution structural MRI. The majority of participants found the difficulty level of the mCAPP game to be “just right”. Accuracy on the mCAPP correlated with performance on memory and executive measures, while speed of performance on the mCAPP correlated with performance on attention and executive function measures. Longer trial duration correlated with measures of the parahippocampal cortex. The relationship of mCAPP variables with molecular biomarkers, at-home and burst testing, and development of additional cognitive measures will also be discussed.

Tau pathology associates with in vivo cortical thinning in Lewy body disorders

OBJECTIVES

To investigate the impact of Alzheimer's disease (AD) co-pathology on an in vivo structural measure of neurodegeneration in Lewy body disorders (LBD).

METHODS

We studied 72 LBD patients (Parkinson disease (PD) = 2, PD-MCI = 25, PD with dementia = 10, dementia with Lewy bodies = 35) with either CSF analysis or neuropathological examination and structural MRI during life. The cohort was divided into those harboring significant AD co-pathology, either at autopsy (intermediate/high AD neuropathologic change) or with CSF signature indicating AD co-pathology (t-tau/Aβ1-42  > 0.3) (LBD+AD, N = 19), and those without AD co-pathology (LBD-AD, N = 53). We also included a reference group of 25 patients with CSF biomarker-confirmed amnestic AD. We investigated differences in MRI cortical thickness estimates between groups, and in the 21 autopsied LBD patients (LBD-AD = 14, LBD+AD = 7), directly tested the association between antemortem MRI and post-mortem burdens of tau, Aβ, and alpha-synuclein using digital histopathology in five representative neocortical regions.

RESULTS

The LBD+AD group was characterized by cortical thinning in anterior/medial and lateral temporal regions (P < 0.05 FWE-corrected) relative to LBD-AD. In LBD+AD, cortical thinning was most pronounced in temporal neocortex, whereas the AD reference group showed atrophy that equally encompassed temporal, parietal and frontal neocortex. In autopsied LBD, we found an inverse correlation with cortical thickness and post-mortem tau pathology, while cortical thickness was not significantly associated with Aβ or alpha-synuclein pathology.

INTERPRETATION

LBD+AD is characterized by temporal neocortical thinning on MRI, and cortical thinning directly correlated with post-mortem histopathologic burden of tau, suggesting that tau pathology influences the pattern of neurodegeneration in LBD.

Neurofilament Light Chain Related to Longitudinal Decline in Frontotemporal Lobar Degeneration

Objective

Accurate diagnosis and prognosis of frontotemporal lobar degeneration (FTLD) during life is an urgent concern in the context of emerging disease-modifying treatment trials. Few CSF markers have been validated longitudinally in patients with known pathology, and we hypothesized that CSF neurofilament light chain (NfL) would be associated with longitudinal cognitive decline in patients with known FTLD-TAR DNA binding protein ~43kD (TDP) pathology.

Methods

This case-control study evaluated CSF NfL, total tau, phosphorylated tau, and β-amyloid_1-42 in patients with known FTLD-tau or FTLD-TDP pathology (n = 50) and healthy controls (n = 65) and an extended cohort of clinically diagnosed patients with likely FTLD-tau or FTLD-TDP (n = 148). Regression analyses related CSF analytes to longitudinal cognitive decline (follow-up ∼1 year), controlling for demographic variables and core AD CSF analytes.

Results

In FTLD-TDP with known pathology, CSF NfL is significantly elevated compared with controls and significantly associated with longitudinal decline on specific executive and language measures, after controlling for age, disease duration, and core AD CSF analytes. Similar findings are found in the extended cohort, also including clinically identified likely FTLD-TDP. Although CSF NfL is elevated in FTLD-tau compared with controls, the association between NfL and longitudinal cognitive decline is limited to executive measures.

Conclusion

CSF NfL is associated with longitudinal clinical decline in relevant cognitive domains in patients with FTLD-TDP after controlling for demographic factors and core AD CSF analytes and may also be related to longitudinal decline in executive functioning in FTLD-tau.

Non-memory cognitive symptom development in Alzheimer's disease

BACKGROUND AND PURPOSE

Memory is known to be the most common first symptom in Alzheimer's disease (AD). Assessing non-memory cognitive symptom development in AD is important for understanding disease progression and the potential identification of treatment-responsive subtypes.

METHODS

Data from the National Alzheimer's Coordinating Center were examined. Logistic regression models were fitted evaluating the development of judgement, language, visuospatial and attention symptoms at first and second visits to Alzheimer's Disease Centers. Predictors were age and prior symptoms, adjusting for symptom length and sex. The models were then refitted assessing apolipoprotein E ε4 (APOE-ε4) effects.

RESULTS

Each decade reduction in presentation age increased the odds of language, visuospatial and attention symptom development at both visits by 8%-18% (P < 0.05, all tests), and judgement symptoms at the second visit by 13% (P < 0.05). Prior symptoms were not equally predictive of symptom development. For example, having first predominant language symptoms carried the lowest risk of developing other first-visit symptoms and having memory symptoms was a stronger predictor of developing judgement than other symptoms. The APOE-ε4 gene showed little impact on symptom development when included as a predictor.

CONCLUSIONS

Our findings provide support for the concept that younger-onset AD is associated with the progressive development of more non-memory symptoms beyond the first time point. Associations between symptoms were evident, which may reflect that pathology can remain isolated in a network for some time. APOE-ε4 status had little influence on cognitive symptom development which may indicate that the effect it has occurs very early in the disease course.

0861 Age, Race, And Continuous Positive Airway Pressure (CPAP) Confidence Score At 1-week Predict 3-month CPAP Adherence In Older Adults With Amnestic Mild Cognitive Impairment And Moderate To Severe Obstructive Sleep Apnea

Introduction

Adherence to continuous positive airway pressure (CPAP) may delay cognitive decline in older adults with obstructive sleep apnea (OSA) and amnestic mild cognitive impairment (MCI), defined as deficits in memory that do not significantly impact daily functioning. The aim of this analysis was to identify predictors of CPAP adherence in this population.

Methods

Data are from Memories 2, an ongoing multisite clinical trial on the effect of treatment of moderate to severe OSA on cognitive decline in older adults 65-85 years of age who have amnestic MCI. Unadjusted and adjusted linear models were used to examine predictors of mean hours of CPAP use at 3 months. Predictors were age, sex (male/female), race (White/Non-White), education (more than high school, less than high school), Apnea-hypopnea index (AHI), Epworth Sleepiness Scale (ESS), and CPAP Comfort and Confidence scores at 7 days. Collinearity in the adjusted model for CPAP use at 3 months was examined using the variance inflation factor.

Results

Of 57 participants, most were male (54%), White (72%), with a mean age of 66.3 years (SD: 6.1). Mean AHI in this sample was 35.1 (SD: 19.9), with mean daily hours of CPAP use at 3 months 5.3 hours (SD: 2.3). Adjusted linear model results demonstrated that younger age (β=-0.13, SE=0.04, p=0.0032), White race (β=2.56, SE=0.58, p&lt;0.0001), and higher 7-day CPAP Confidence score (β=0.48, SE=0.17, p=0.0086) were significantly associated with CPAP use at 3 months. Sex, education, AHI, ESS, and CPAP comfort were not statistically significant predictors of adherence.

Conclusion

Tailored interventions to increase self-efficacy during the first 7 days of CPAP treatment, especially in Non-Whites and those older than 74 years, may improve long-term CPAP adherence in older adults with amnestic MCI.

Support

R01AG054435

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.

Neurodegenerative disease concomitant proteinopathies are prevalent, age-related and APOE4-associated

Lewy bodies commonly occur in Alzheimer's disease, and Alzheimer's disease pathology is frequent in Lewy body diseases, but the burden of co-pathologies across neurodegenerative diseases is unknown. We assessed the extent of tau, amyloid-β, α-synuclein and TDP-43 proteinopathies in 766 autopsied individuals representing a broad spectrum of clinical neurodegenerative disease. We interrogated pathological Alzheimer's disease (n = 247); other tauopathies (n = 95) including Pick's disease, corticobasal disease and progressive supranuclear palsy; the synucleinopathies (n = 164) including multiple system atrophy and Lewy body disease; the TDP-43 proteinopathies (n = 188) including frontotemporal lobar degeneration with TDP-43 inclusions and amyotrophic lateral sclerosis; and a minimal pathology group (n = 72). Each group was divided into subgroups without or with co-pathologies. Age and sex matched logistic regression models compared co-pathology prevalence between groups. Co-pathology prevalence was similar between the minimal pathology group and most neurodegenerative diseases for each proteinopathy: tau was nearly universal (92-100%), amyloid-β common (20-57%); α-synuclein less common (4-16%); and TDP-43 the rarest (0-16%). In several neurodegenerative diseases, co-pathology increased: in Alzheimer's disease, α-synuclein (41-55%) and TDP-43 (33-40%) increased; in progressive supranuclear palsy, α-synuclein increased (22%); in corticobasal disease, TDP-43 increased (24%); and in neocortical Lewy body disease, amyloid-β (80%) and TDP-43 (22%) increased. Total co-pathology prevalence varied across groups (27-68%), and was increased in high Alzheimer's disease, progressive supranuclear palsy, and neocortical Lewy body disease (70-81%). Increased age at death was observed in the minimal pathology group, amyotrophic lateral sclerosis, and multiple system atrophy cases with co-pathologies. In amyotrophic lateral sclerosis and neocortical Lewy body disease, co-pathologies associated with APOE ɛ4. Lewy body disease cases with Alzheimer's disease co-pathology had substantially lower Mini-Mental State Examination scores than pure Lewy body disease. Our data imply that increased age and APOE ɛ4 status are risk factors for co-pathologies independent of neurodegenerative disease; that neurodegenerative disease severity influences co-pathology as evidenced by the prevalence of co-pathology in high Alzheimer's disease and neocortical Lewy body disease, but not intermediate Alzheimer's disease or limbic Lewy body disease; and that tau and α-synuclein strains may also modify co-pathologies since tauopathies and synucleinopathies had differing co-pathologies and burdens. These findings have implications for clinical trials that focus on monotherapies targeting tau, amyloid-β, α-synuclein and TDP-43.

Quantitative assessment of finger tapping characteristics in mild cognitive impairment, Alzheimer's disease, and Parkinson's disease

BACKGROUND

Fine motor impairments are common in neurodegenerative disorders, yet standardized, quantitative measurements of motor abilities are uncommonly used in neurological practice. Thus, understanding and comparing fine motor abilities across disorders have been limited.

OBJECTIVES

The current study compared differences in finger tapping, inter-tap interval, and variability in Alzheimer's disease (AD), Parkinson's disease (PD), mild cognitive impairment (MCI), and healthy older adults (HOA).

METHODS

Finger tapping was measured using a highly sensitive light-diode finger tapper. Total number of finger taps, inter-tap interval, and intra-individual variability (IIV) of finger tapping was measured and compared in AD (n = 131), PD (n = 63), MCI (n = 46), and HOA (n = 62), controlling for age and sex.

RESULTS

All patient groups had fine motor impairments relative to HOA. AD and MCI groups produced fewer taps with longer inter-tap interval and higher IIV compared to HOA. The PD group, however, produced more taps with shorter inter-tap interval and higher IIV compared to HOA.

CONCLUSIONS

Disease-specific changes in fine motor function occur in the most common neurodegenerative diseases. The findings suggest that alterations in finger tapping patterns are common in AD, MCI, and PD. In addition, the present results underscore the importance of motor dysfunction even in neurodegenerative disorders without primary motor symptoms.

Deep Brain Stimulation Targeting the Fornix for Mild Alzheimer Dementia (the ADvance Trial): A Two Year Follow-up Including Results of Delayed Activation

BACKGROUND

Given recent challenges in developing new treatments for Alzheimer dementia (AD), it is vital to explore alternate treatment targets, such as neuromodulation for circuit dysfunction. We previously reported an exploratory Phase IIb double-blind trial of deep brain stimulation targeting the fornix (DBS-f) in mild AD (the ADvance trial). We reported safety but no clinical benefits of DBS-f versus the delayed-on (sham) treatment in 42 participants after one year. However, secondary post hoc analyses of the one-year data suggested a possible DBS-f benefit for participants≥65 years.

OBJECTIVE

To examine the long-term safety and clinical effects of sustained and delayed-on DBS-f treatment of mild AD after two years.

METHODS

42 participants underwent implantation of DBS-f electrodes, with half randomized to active DBS-f stimulation (early on) for two years and half to delayed-on (sham) stimulation after 1 year to provide 1 year of active DBS-f stimulation (delayed on). We evaluated safety and clinical outcomes over the two years of the trial.

RESULTS

DBS-f had a favorable safety profile with similar rates of adverse events across both trial phases (years 1 and 2) and between treatment arms. There were no differences between treatment arms on any primary clinical outcomes. However, post-hoc age group analyses suggested a possible benefit among older (>65) participants.

CONCLUSION

DBS-f was safe. Additional study of mechanisms of action and methods for titrating stimulation parameters will be needed to determine if DBS has potential as an AD treatment. Future efficacy studies should focus on patients over age 65.

Awareness of Mild Cognitive Impairment and Mild Alzheimer's Disease Dementia Diagnoses Associated With Lower Self-Ratings of Quality of Life in Older Adults

Objective

This study examined how awareness of diagnostic label impacted self-reported quality of life (QOL) in persons with varying degrees of cognitive impairment.

Method

Older adults (n = 259) with normal cognition, Mild Cognitive Impairment (MCI), or mild Alzheimer's disease dementia (AD) completed tests of cognition and self-report questionnaires that assessed diagnosis awareness and multiple domains of QOL: cognitive problems, activities of daily living, physical functioning, mental wellbeing, and perceptions of one's daily life. We compared measures of QOL by cognitive performance, diagnosis awareness, and diagnostic group.

Results

Persons with MCI or AD who were aware of their diagnosis reported lower average satisfaction with daily life (QOL-AD), basic functioning (BADL Scale), and physical wellbeing (SF-12 PCS), and more difficulties in daily life (DEM-QOL) than those who were unaware (all p ≤ .007). Controlling for gender, those expecting their condition to worsen over time reported greater depression (GDS), higher stress (PSS), lower quality of daily life (QOL-AD, DEM-QOL), and more cognitive difficulties (CDS) compared to others (all p < .05).

Discussion

Persons aware of their diagnostic label-either MCI or AD-and its prognosis report lower QOL than those unaware of these facts about themselves. These relationships are independent of the severity of cognitive impairment.

Neural Correlates of Verbal Episodic Memory and Lexical Retrieval in Logopenic Variant Primary Progressive Aphasia

Objective: Logopenic variant primary progressive aphasia (lvPPA) is commonly associated with Alzheimer's disease (AD) pathology. But lvPPA patients display different cognitive and anatomical profile from the common clinical AD patients, whose verbal episodic memory is primarily affected. Reports of verbal episodic memory difficulty in lvPPA are inconsistent, and we hypothesized that their lexical retrieval impairment contributes to verbal episodic memory performance and is associated with left middle temporal gyrus atrophy.

Methods: We evaluated patients with lvPPA (n = 12) displaying prominent word-finding and repetition difficulties, and a demographically-matched cohort of clinical Alzheimer's disease (AD, n = 26), and healthy seniors (n = 16). We assessed lexical retrieval with confrontation naming and verbal episodic memory with delayed free recall. Whole-brain regressions related naming and delayed free recall to gray matter atrophy. Medial temporal lobe (MTL) subfields were examined using high in-plane resolution imaging.

Results: lvPPA patients had naming and delayed free recall impairments, but intact recognition memory. In lvPPA, delayed free recall was related to naming; both were associated with left middle temporal gyrus atrophy but not MTL atrophy. Despite cerebrospinal fluid evidence consistent with AD pathology, examination of MTL subfields revealed no atrophy in lvPPA. While AD patients displayed impaired delayed free recall, this deficit did not correlate with naming. Regression analyses related delayed free recall deficits in clinical AD patients to MTL subfield atrophy, and naming to left middle temporal gyrus atrophy.

Conclusion: Unlike amnestic AD patients, MTL subfields were not affected in lvPPA patients. Verbal episodic memory deficit observed in lvPPA was unlikely to be due to a hippocampal-mediated mechanism but appeared to be due to poor lexical retrieval. Relative sparing of MTL volume and intact recognition memory are consistent with previous reports of hippocampal-sparing variant cases of AD pathology, where neurofibrillary tangles are disproportionately distributed in cortical areas with relative sparing of the hippocampus. This suggests that AD neuropathology in lvPPA may originate in neuronal networks outside of the MTL, which deviates from the typical Braak staging pattern of spreading pathology in clinical AD.

Heterogeneity of neuroanatomical patterns in prodromal Alzheimer's disease: links to cognition, progression and biomarkers

See Coulthard and Knight (doi:10.1093/aww335) for a scientific commentary on this article.Individuals with mild cognitive impairment and Alzheimer's disease clinical diagnoses can display significant phenotypic heterogeneity. This variability likely reflects underlying genetic, environmental and neuropathological differences. Characterizing this heterogeneity is important for precision diagnostics, personalized predictions, and recruitment of relatively homogeneous sets of patients into clinical trials. In this study, we apply state-of-the-art semi-supervised machine learning methods to the Alzheimer's disease Neuroimaging cohort (ADNI) to elucidate the heterogeneity of neuroanatomical differences between subjects with mild cognitive impairment (n = 530) and Alzheimer's disease (n = 314) and cognitively normal individuals (n = 399), thereby adding to an increasing literature aiming to establish neuroanatomical and neuropathological (e.g. amyloid and tau deposition) dimensions in Alzheimer's disease and its prodromal stages. These dimensional approaches aim to provide surrogate measures of heterogeneous underlying pathologic processes leading to cognitive impairment. We relate these neuroimaging patterns to cerebrospinal fluid biomarkers, white matter hyperintensities, cognitive and clinical measures, and longitudinal trajectories. We identified four such atrophy patterns: (i) individuals with largely normal neuroanatomical profiles, who also turned out to have the least abnormal cognitive and cerebrospinal fluid biomarker profiles and the slowest clinical progression during follow-up; (ii) individuals with classical Alzheimer's disease neuroanatomical, cognitive, cerebrospinal fluid biomarkers and clinical profile, who presented the fastest clinical progression; (iii) individuals with a diffuse pattern of atrophy with relatively less pronounced involvement of the medial temporal lobe, abnormal cerebrospinal fluid amyloid-β1-42 values, and proportionally greater executive impairment; and (iv) individuals with notably focal involvement of the medial temporal lobe and a slow steady progression, likely representing in early Alzheimer's disease stages. These four atrophy patterns effectively define a 4-dimensional categorization of neuroanatomical alterations in mild cognitive impairment and Alzheimer's disease that can complement existing dimensional approaches for staging Alzheimer's disease using a variety of biomarkers, which offer the potential for enabling precision diagnostics and prognostics, as well as targeted patient recruitment of relatively homogeneous subgroups of subjects for clinical trials.

Clinical Application of Automatic Segmentation of Medial Temporal Lobe Subregions in Prodromal and Dementia-Level Alzheimer's Disease

BACKGROUND

Volumetry of medial temporal lobe (MTL) structures to diagnose Alzheimer's disease (AD) in its earliest symptomatic stage could be of great importance for interventions or disease modifying pharmacotherapy.

OBJECTIVE

This study aimed to demonstrate the first application of an automatic segmentation method of MTL subregions in a clinical population. Automatic segmentation of magnetic resonance images (MRIs) in a research population has previously been shown to detect evidence of neurodegeneration in MTL subregions and to help discriminate AD and mild cognitive impairment (MCI) from a healthy comparison group.

METHODS

Clinical patients were selected and T2-weighted MRI scan quality was checked. An automatic segmentation method of hippocampal subfields (ASHS) was applied to scans of 67 AD patients, 38 amnestic MCI patients, and 57 healthy controls. Hippocampal subfields, entorhinal cortex (ERC), and perirhinal cortex were automatically labeled and subregion volumes were compared between groups.

RESULTS

One fourth of all scans were excluded due to bad scan quality. There were significant volume reductions in all subregions, except BA36, in aMCIs (p < 0.001), most prominently in Cornu Ammonis 1 (CA1) and ERC, and in all subregions in AD. However, sensitivity of CA1 and ERC hardly differed from sensitivity of WH in aMCI and AD.

CONCLUSION

Applying automatic segmentation of MTL subregions in a clinical setting as a potential biomarker for prodromal AD is feasible, but issues of image quality due to motion remain to be addressed. CA1 and ERC provided strongest group discrimination in differentiating aMCIs from controls, but discriminatory power of different subfields was low overall.

Alzheimer's disease first symptoms are age dependent: Evidence from the NACC dataset

INTRODUCTION

Determining the relationship between age and Alzheimer's disease (AD) presentation is important to improve understanding and provide better patient services.

METHODS

We used AD patient data (N = 7815) from the National Alzheimer Coordinating Center database and multinomial logistic regression to investigate presentation age and first cognitive/behavioral symptoms.

RESULTS

The odds of having a nonmemory first cognitive symptom (including impairment in judgment and problem solving, language, and visuospatial function) increased with younger age (P < .001, all tests). Compared with apathy/withdrawal, the odds of having depression and "other" behavioral symptoms increased with younger age (P < .02, both tests), whereas the odds of having psychosis and no behavioral symptom increased with older age (P < .001, both tests).

DISCUSSION

There is considerable heterogeneity in the first cognitive/behavioral symptoms experienced by AD patients. Proportions of these symptoms change with age with patients experiencing increasing nonmemory cognitive symptoms and more behavioral symptoms at younger ages.

Transcranial Direct Current Stimulation Enhances Verbal Working Memory Training Performance over Time and Near Transfer Outcomes

Studies attempting to increase working memory (WM) capacity show promise in enhancing related cognitive functions but have also raised criticism in the broader scientific community given the inconsistent findings produced by these studies. Transcranial direct current stimulation (tDCS) has been shown to enhance WM performance in a single session [Fregni, F., Boggio, P., Nitsche, M., Bermpohl, F., Anatal, A., Feredoes, E., et al. Anodal transcranial direct current stimulation of prefrontal cortex enhances working memory. Experimental Brain Research, 166, 23–30, 2005]; however, the extent to which tDCS might enhance learning on a WM training regime and the extent to which learning gains might transfer outside the training task remains largely unknown. To this end, participants engaged in an adaptive WM training task [previously utilized in Richmond, L., Morrison, A., Chein, J., & Olson, I. Working memory training and transfer in older adults. Psychology & Aging, 26, 813–822, 2011; Chein, J., & Morrison, A. Expanding the mind's workspace: Training and transfer effects with a complex working memory span task. Psychonomic Bulletin & Review, 17, 193–199, 2010] for 10 sessions over 2 weeks, concurrent with either active or sham stimulation of dorsolateral pFC. Before and after training, a battery of tests tapping domains known to relate to WM abilities was administered. Results show that tDCS enhanced learning on the verbal portion of the training task by 3.65 items. Furthermore, tDCS was shown to enhance near transfer to other untrained WM tasks in comparison with a no-contact control group. These results lend support to the idea that tDCS might bolster training and transfer gains in populations with compromised WM abilities.

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.

In vivo analysis of hippocampal subfield atrophy in mild cognitive impairment via semi-automatic segmentation of T2-weighted MRI

The measurement of hippocampal volumes using MRI is a useful in-vivo biomarker for detection and monitoring of early Alzheimer's disease (AD), including during the amnestic mild cognitive impairment (a-MCI) stage. The pathology underlying AD has regionally selective effects within the hippocampus. As such, we predict that hippocampal subfields are more sensitive in discriminating prodromal AD (i.e., a-MCI) from cognitively normal controls than whole hippocampal volumes, and attempt to demonstrate this using a semi-automatic method that can accurately segment hippocampal subfields. High-resolution coronal-oblique T2-weighted images of the hippocampal formation were acquired in 45 subjects (28 controls and 17 a-MCI (mean age: 69.5 ± 9.2; 70.2 ± 7.6)). CA1, CA2, CA3, and CA4/DG subfields, along with head and tail regions, were segmented using an automatic algorithm. CA1 and CA4/DG segmentations were manually edited. Whole hippocampal volumes were obtained from the subjects' T1-weighted anatomical images. Automatic segmentation produced significant group differences in the following subfields: CA1 (left: p = 0.001, right: p = 0.038), CA4/DG (left: p = 0.002, right: p = 0.043), head (left: p = 0.018, right: p = 0.002), and tail (left: p = 0.019). After manual correction, differences were increased in CA1 (left: p < 0.001, right: p = 0.002), and reduced in CA4/DG (left: p = 0.029, right: p = 0.221). Whole hippocampal volumes significantly differed bilaterally (left: p = 0.028, right: p = 0.009). This pattern of atrophy in a-MCI is consistent with the topography of AD pathology observed in postmortem studies, and corrected left CA1 provided stronger discrimination than whole hippocampal volume (p = 0.03). These results suggest that semi-automatic segmentation of hippocampal subfields is efficient and may provide additional sensitivity beyond whole hippocampal volumes.

Ask the experts: PET amyloid imaging: can its diagnostic potential be effectively realized in the clinic?

Dr Fleisher is a geriatric Neurologist practicing in the Memory Disorders Clinic and the Associate Director of brain imaging at the Banner Alzheimer’s Institute in Phoenix (AZ, USA). Dr Fleisher is also an Associate Professor in the department of Neurosciences at the University of California, San Diego. He completed medical school at the University of Rochester, School of Medicine, Rochester New York, and went on to do his adult neurology training at Johns Hopkins Hospital in Baltimore, MD. After his clinical neurology training Dr Fleisher completed a post-doctorate research and clinical dementia fellowship at the University of California, San Diego. He also completed a functional neuroimaging research post-doctorate VA fellowship while in San Diego, and obtained a masters of advanced studies degree in clinical research. Since 2003 he has been the medical director of the Alzheimer’s Disease Cooperative Study, where he has been involved in the management of numerous clinical treatment and biomarker trials. Dr Fleisher has been a project director, principal investigator in numerous NIH and pharmaceutical sponsored clinical trials related to dementia and is well published in the field of Alzheimer’s disease clinical trials, imaging and biomarker development. His current research is in developing imaging techniques to identify AD prior to clinical dementia.

Dr Wolk is an Assistant Professor of Neurology in the Cognitive Neurology Division at the University of Pennsylvania (PA, USA) and Assistant Director of the Penn Memory Center. He is board-certified in Neurology. He completed his medical training at Johns Hopkins University, a Neurology Residency at the University of Pennsylvania, and Clinical Fellowship training in Cognitive and Behavioral Neurology at Brigham and Women’s Hospital/Harvard Medical School. He completed a post-doctoral research fellowship studying memory in Alzheimer’s Disease at Brigham and Women’s Hospital and Harvard University. Prior to his return to Penn, he was an Assistant Professor at the University of Pittsburgh and their Alzheimer’s Disease Research Center. Much of his work has also focused on examining biomarkers that differentiate healthy aging from early Alzheimer’s Disease. A particular focus has been on the cognitive neuroscience of memory decline associated with aging and mild cognitive impairment/Alzheimer’s disease using techniques including behavioral testing, event-related potentials, structural MRI and amyloid imaging.