CSF levels of Aβ1-38/Aβ1-40/Aβ1-42 and (11)C PiB-PET studies in three clinical variants of primary progressive aphasia and Alzheimer's disease

Recurrent Lobar Hemorrhages and Multiple Cortical Superficial Siderosis in a Patient of Alzheimer's Disease With Homozygous APOE ε2 Allele Presenting Hypobetalipoproteinemia and Pathological Findings of 18F-THK5351 Positron Emission Tomography: A Case Report

In Alzheimer's disease, the apolipoprotein E gene (APOE) ε2 allele is a protective genetic factor, whereas the APOE ε4 allele is a genetic risk factor. However, both the APOE ε2 and the APOE ε4 alleles are genetic risk factors for lobar intracerebral hemorrhage. The reasons for the high prevalence of lobar intracerebral hemorrhage and the low prevalence of Alzheimer's disease with the APOE ε2 allele remains unknown. Here, we describe the case of a 79-year-old Japanese female with Alzheimer's disease, homozygous for the APOE ε2 allele. This patient presented with recurrent lobar hemorrhages and multiple cortical superficial siderosis. The findings on the ¹¹C-labeled Pittsburgh Compound B-positron emission tomography (PET) were characteristic of Alzheimer's disease. ¹⁸F-THK5351 PET revealed that the accumulation of ¹⁸F-THK 5351 in the right pyramidal tract at the pontine level, the cerebral peduncle of the midbrain, and the internal capsule, reflecting the lesions of the previous lobar intracerebral hemorrhage in the right frontal lobe. Moreover, ¹⁸F-THK5351 accumulated in the bilateral globus pallidum, amygdala, caudate nuclei, and the substantia nigra of the midbrain, which were probably off-target reaction, by binding to monoamine oxidase B (MAO-B). ¹⁸F-THK5351 were also detected in the periphery of prior lobar hemorrhages and a cortical subarachnoid hemorrhage, as well as in some, but not all, areas affected by cortical siderosis. Besides, ¹⁸F-THK5351 retentions were observed in the bilateral medial temporal cortices and several cortical areas without cerebral amyloid angiopathy or prior hemorrhages, possibly where tau might accumulate. This is the first report of a patient with Alzheimer's disease, carrying homozygous APOE ε2 allele and presenting with recurrent lobar hemorrhages, multiple cortical superficial siderosis, and immunohistochemically vascular amyloid β. The ¹⁸F-THK5351 PET findings suggested MAO-B concentrated regions, astroglial activation, Waller degeneration of the pyramidal tract, neuroinflammation due to CAA related hemorrhages, and possible tau accumulation.

Cerebral Microbleeds, Cerebrospinal Fluid, and Neuroimaging Markers in Clinical Subtypes of Alzheimer's Disease

Lobar cerebral microbleeds (CMBs) in Alzheimer's disease (AD) are associated with cerebral amyloid angiopathy (CAA) due to vascular amyloid beta (Aβ) deposits. However, the relationship between lobar CMBs and clinical subtypes of AD remains unknown. Here, we enrolled patients with early- and late-onset amnestic dominant AD, logopenic variant of primary progressive aphasia (lvPPA) and posterior cortical atrophy (PCA) who were compatible with the AD criteria. We then examined the levels of cerebrospinal fluid (CSF) biomarkers [Aβ1-42, Aβ1-40, Aβ1-38, phosphorylated tau 181 (P-Tau), total tau (T-Tau), neurofilament light chain (NFL), and chitinase 3-like 1 protein (YKL-40)], analyzed the number and localization of CMBs, and measured the cerebral blood flow (CBF) volume by ^99mTc-ethyl cysteinate dimer single photon emission computerized tomography (^99mTc ECD-SPECT), as well as the mean cortical standard uptake value ratio by ¹¹C-labeled Pittsburgh Compound B-positron emission tomography (¹¹C PiB-PET). Lobar CMBs in lvPPA were distributed in the temporal, frontal, and parietal lobes with the left side predominance, while the CBF volume in lvPPA significantly decreased in the left temporal area, where the number of lobar CMBs and the CBF volumes showed a significant inversely correlation. The CSF levels of NFL in lvPPA were significantly higher compared to the other AD subtypes and non-demented subjects. The numbers of lobar CMBs significantly increased the CSF levels of NFL in the total AD patients, additionally, among AD subtypes, the CSF levels of NFL in lvPPA predominantly were higher by increasing number of lobar CMBs. On the other hand, the CSF levels of Aβ1-38, Aβ1-40, Aβ1-42, P-Tau, and T-Tau were lower by increasing number of lobar CMBs in the total AD patients. These findings may suggest that aberrant brain hypoperfusion in lvPPA was derived from the brain atrophy due to neurodegeneration, and possibly may involve the aberrant microcirculation causing by lobar CMBs and cerebrovascular injuries, with the left side dominance, consequently leading to a clinical phenotype of logopenic variant.

Increased Neurofilament Light Chain and YKL-40 CSF Levels in One Japanese IBMPFD Patient With VCP R155C Mutation: A Clinical Case Report With CSF Biomarker Analyses

Inclusion body myopathy (IBM) with Paget's disease of bone (PDB) and frontotemporal dementia (IBMPFD) presents with multiple symptoms and an unknown etiology. Valosin-containing protein (VCP) has been identified as the main causative gene of IBMPFD. However, no studies on neurofilament light chain (NFL) as a cerebrospinal fluid (CSF) marker of axonal neurodegeneration or on YKL-40 as a CSF marker of glial neuroinflammation have been conducted in IBMPFD patients with VCP mutations. A 65-year-old man presented with progressive muscle atrophy and weakness of all limbs, non-fluent aphasia, and changes in personality and behavior. Cerebral MRI revealed bilateral frontal and temporal atrophy. ^99mTc-HMDP bone scintigraphy and pelvic CT revealed remodeling changes and active osteoblastic accumulations in the right medial iliac bone. Muscle biopsy demonstrated multiple rimmed vacuoles in muscle cells with myogenic and neurogenic pathological alterations. After the patient was clinically diagnosed with IBMPFD, DNA analysis of the VCP gene revealed a cytosine (C) to thymine (T) (C→ T) mutation, resulting in an amino acid exchange of arginine to cysteine (p.R155C mutation). The CSF levels of NFL at two time points (12 years apart) were higher than those in non-dementia controls (CTR) and Alzheimer's disease (AD); lower than those in frontotemporal dementia with motor neuron disease (FTD-MND); and comparable to those in patients with behavioral variant frontotemporal dementia (bvFTD), progressive supranuclear palsy (PSP), and corticobasal syndrome (CBS). The CSF levels of YKL-40 were comparable at both time points and higher than those in CTR; lower than those in FTD-MND; and comparable to those in bvFTD, PSP, CBS, and AD. The CSF levels of phosphorylated tau 181 (P-Tau) and total tau (T-Tau) were not significantly different from those in CTR and other neurodegenerative diseases, except those in AD, which were significantly elevated. This is the first report that demonstrates increased NFL and YKL-40 CSF levels in an IBMPFD patient with a VCP mutation (p.R155C); NFL and YKL-40 levels were comparable to those in bvFTD, PSP, CBS, and AD and higher than those in CTR. Our results suggest that IBMPFD neuropathology may involve both axonal neurodegeneration and glial neuroinflammation.

Deep White Matter Lesions Are Associated with Early Recognition of Dementia in Alzheimer's Disease

Neuroimages of cerebral amyloid-β (Aβ) accumulation and small vessel disease (SVD) were examined in patients with various types of cognitive disorders using 11C-labeled Pittsburgh Compound B-positron emission tomography (PiB-PET) and magnetic resonance imaging (MRI). The mean cortical standardized uptake value ratio (mcSUVR) was applied for a quantitative analysis of PiB-PET data. The severity of white matter lesions (WML) and enlarged perivascular spaces (EPVS) on MRI were assessed to evaluate complicating cerebral SVD using semiquantitative scales. In homozygous apolipoprotein E ɛ3/ɛ3 carriers, the incidence of more severe WML and EPVS was higher in PiB-positive than PiB-negative patients, indicating that WML and EPVS might be associated with enhanced Aβ accumulation. An association study between PiB-PET and MRI findings revealed that higher WML grades significantly correlate with lower mcSUVRs, especially in the frontal area, indicating that more severe ischemic MRI findings are associated with milder Aβ accumulation among patients with Alzheimer's disease. In these patients SVD may accelerate the occurrence of cognitive decline and facilitate early recognition of dementia.

Importance of Neuropathological Diagnosis of Dementia Patients in Family Practice

Introduction:

Creutzfeldt–Jakob disease (CJD) is an important dementia disorder. However, clinical diagnosis can be difficult and delayed for many primary physicians caring for dementia patients. The aim of the present study was to describe clinical and neuropathological results of an individual with CJD who was seen by a community hospital. Our report may inform many primary physicians on understanding the significance of CJD.

Methods:

Clinical information was obtained from medical records. Neuropathological and biochemical analyses were performed using autopsied brain.

Results:

A 58-year-old Japanese man who had worked as a carpenter developed memory and executive function impairments. He was initially diagnosed as having Alzheimer’s disease based on clinical and neuroradiological analyses. Myoclonus was observed in the later stage of clinical course. Hyperintense lesions on diffusion-weighted images were observed in the cerebral cortex in later stage. Analysis of cerebrospinal fluid showed increased levels of total tau and phospho-tau protein. However, 14-3-3 protein and amyloid β (1–42) were normal. Genetic analysis of the PRNP gene showed methionine homozygosity at codon 129 and glutamate homozygosity at codon 219. The results of neuropathological analysis were consistent with sporadic CJD (MM2 cortical type with some type 1 pattern of 3F4 immunoreactivity). Western blot analysis of the frontal and cerebellar cortex revealed a type 2 and type 1 pattern of proteinase K (PK)-resistant prion protein, respectively. No Alzheimer’s pathology was present.

Conclusions:

Our experience may help primary physicians to assess dementia patients. Since atypical forms of prion disease are now well-established, we need to consider prion disease in dementia patients. Clinical examination alone is not enough for dementia workup; thus, we must understand the importance of neuropathological study and encourage autopsy to reach a definite diagnosis of dementia.

Prevalence of amyloid-β pathology in distinct variants of primary progressive aphasia

OBJECTIVE

To estimate the prevalence of amyloid positivity, defined by positron emission tomography (PET)/cerebrospinal fluid (CSF) biomarkers and/or neuropathological examination, in primary progressive aphasia (PPA) variants.

METHODS

We conducted a meta-analysis with individual participant data from 1,251 patients diagnosed with PPA (including logopenic [lvPPA, n = 443], nonfluent [nfvPPA, n = 333], semantic [svPPA, n = 401], and mixed/unclassifiable [n = 74] variants of PPA) from 36 centers, with a measure of amyloid-β pathology (CSF [n = 600], PET [n = 366], and/or autopsy [n = 378]) available. The estimated prevalence of amyloid positivity according to PPA variant, age, and apolipoprotein E (ApoE) ε4 status was determined using generalized estimating equation models.

RESULTS

Amyloid-β positivity was more prevalent in lvPPA (86%) than in nfvPPA (20%) or svPPA (16%; p < 0.001). Prevalence of amyloid-β positivity increased with age in nfvPPA (from 10% at age 50 years to 27% at age 80 years, p < 0.01) and svPPA (from 6% at age 50 years to 32% at age 80 years, p < 0.001), but not in lvPPA (p = 0.94). Across PPA variants, ApoE ε4 carriers were more often amyloid-β positive (58.0%) than noncarriers (35.0%, p < 0.001). Autopsy data revealed Alzheimer disease pathology as the most common pathologic diagnosis in lvPPA (76%), frontotemporal lobar degeneration-TDP-43 in svPPA (80%), and frontotemporal lobar degeneration-TDP-43/tau in nfvPPA (64%).

INTERPRETATION

This study shows that the current PPA classification system helps to predict underlying pathology across different cohorts and clinical settings, and suggests that age and ApoE genotype should be considered when interpreting amyloid-β biomarkers in PPA patients. Ann Neurol 2018;84:737-748.

Elevated CSF GAP-43 is Alzheimer's disease specific and associated with tau and amyloid pathology

Introduction:

The level of the presynaptic protein growth-associated protein 43 (GAP-43) in cerebrospinal fluid (CSF) has previously been shown to be increased in Alzheimer’s disease (AD) and thus may serve as an outcome measure in clinical trials and facilitate earlier disease detection.

Methods:

We developed an enzyme-linked immunosorbent assay for CSF GAP-43 and measured healthy controls (n = 43), patients with AD (n = 275), or patients with other neurodegenerative diseases (n = 344). In a subpopulation (n = 93), CSF GAP-43 concentrations from neuropathologically confirmed cases were related to Aβ plaques, tau, α-synuclein, and TDP-43 pathologies.

Results:

GAP-43 was significantly increased in AD compared to controls and most neurodegenerative diseases and correlated with the magnitude of neurofibrillary tangles and Aβ plaques in the hippocampus, amygdala, and cortex. GAP-43 was not associated to α-synuclein or TDP-43 pathology.

Discussion:

The presynaptic marker GAP-43 is associated with both diagnosis and neuropathology of AD and thus may be useful as a sensitive and specific biomarker for clinical research.

Amyloid PET Positivity in Different Primary Progressive Aphasia Phenotypes

PURPOSE

Primary progressive aphasia (PPA) is a neurological syndrome in which language functions become progressively impaired with relative sparing of memory and other instrumental functions. The pathologic causes of PPA are heterogeneous, but studies suggest that logopenic PPA (LPA) is underpinned by Alzheimer disease (AD) pathology in a high proportion of cases. The purposes of this descriptive and retrospective study were to characterize F-florbetapir PET imaging in a group of patients with a clinical syndrome of PPA, to determine the value of clinical characterization based on language phenotype in predicting the underlying pathology of PPA with F-florbetapir, and to quantify amyloid load in PPA subjects classified as "positive" F-florbetapir scans. Then, we compare the quantification and distribution of F-florbetapir uptake with those of typical, predominantly amnestic AD patients.

METHODS

We conducted a PET study with F-florbetapir in a cohort of 12 right-handed patients diagnosed with PPA: 3 patients with semantic-variant PPA, 5 with nonfluent PPA, 1 with LPA, and 3 unclassifiable patients. We evaluated amyloid deposition between APP groups and 11 patients with typical amnestic AD.

RESULTS

Among the 12 patients with PPA syndrome, 8 (66.7%) were considered as amyloid positive. One of the 3 patients with semantic-variant PPA was F-florbetapir positive. In contrast, 4 of the 5 nonfluent-variant PPA, 2 of the 3 unclassifiable cases and the single patient with LPA were F-florbetapir positive. A significantly higher F-florbetapir uptake was observed in PPA F-florbetapir-positive patients compared with typical AD patients. This difference was observed in all regions of interest, except in posterior cingulate and temporal cortex.

CONCLUSIONS

These results suggest that F-florbetapir PET may be useful in a routine clinical procedure to improve the reliability of identifying AD pathology in patients with PPA syndrome, with different clinical subtypes of the PPA syndrome.

Amyloid pet in primary progressive aphasia: case series and systematic review of the literature

Primary progressive aphasia (PPA) is considered a heterogeneous syndrome, with different clinical subtypes and neuropathological causes. Novel PET biomarkers may help to predict the underlying neuropathology, but many aspects remain unclear. We studied the relationship between amyloid PET and PPA variant in a clinical series of PPA patients. A systematic review of the literature was performed. Patients with PPA were assessed over a 2-year period and classified based on language testing and the International Consensus Criteria as non-fluent/agrammatic (nfvPPA), semantic (svPPA), logopenic variant (lvPPA) or as unclassifiable (ucPPA). All patients underwent a Florbetapir (18-F) PET scan and images were analysed by two nuclear medicine physicians, using a previously validated reading method. Relevant studies published between January 2004 and January 2016 were identified by searching Medline and Web of Science databases. Twenty-four PPA patients were included (13 women, mean age 68.8, SD 8.3 years; range 54-83). Overall, 13/24 were amyloid positive: 0/2 (0%) nfvPPA, 0/4 (0%) svPPA, 10/14 (71.4%) lvPPA and 3/4 (75%) ucPPA (p = 0.028). The systematic review identified seven relevant studies, six including all PPA variants and one only lvPPA. Pooling all studies together, amyloid PET positivity was 122/224 (54.5%) for PPA, 14/52 (26.9%) for nfvPPA, 6/47 (12.8%) for svPPA, 101/119 for lvPPA (84.9%) and 12/22 (54.5%) for ucPPA. Amyloid PET may help to identify the underlying neuropathology in PPA. It could be especially useful in ucPPA, because in these cases it is more difficult to predict pathology. ucPPA is frequently associated with amyloid pathology.

A Dextral Primary Progressive Aphasia Patient with Right Dominant Hypometabolism and Tau Accumulation and Left Dominant Amyloid Accumulation

Background

Primary progressive aphasia (PPA) is a degenerative disease that presents as progressive decline of language ability with preservation of other cognitive functions in the early stages. Three subtypes of PPA are known: progressive nonfluent aphasia, semantic dementia, and logopenic aphasia (LPA).

Patients and Methods

We report the case of a 77-year-old patient with PPA whose clinical findings did not correspond to the three subtypes but mainly fit LPA. Unlike other LPA patients, however, this patient showed a right hemisphere predominant glucose hypometabolism and tau accumulation and a left hemisphere predominant amyloid deposition. The right-handed patient presented with comprehension difficulty followed by problems naming familiar objects. This isolated language problem had deteriorated rapidly for 2 years, followed by memory difficulties and impairment of daily activities. Using a Korean version of the Western Aphasia Battery, aphasia was consistent with a severe form of Wernicke's aphasia. According to the brain magnetic resonance imaging and ¹⁸F-fludeoxyglucose positron emission tomography results, right hemisphere atrophy and hypometabolism, more predominant on the right hemisphere than the left, were apparent despite the fact that Edinburgh Handedness Questionnaire scores indicated strong right-handedness. On Pittsburgh compound B-PET, amyloid accumulation was asymmetrical with the left hemisphere being more predominant than the right, whereas ¹⁸F-T807-PET showed a right dominant tau accumulation.

Conclusions

This is the first report of atypical PPA, in which the patient exhibited crossed aphasia and asymmetrical amyloid accumulation.

Genetic and degenerative disorders primarily causing dementia

Neuroimaging comprises a powerful set of instruments to diagnose the different causes of dementia, clarify their neurobiology, and monitor their treatment. Magnetic resonance imaging (MRI) depicts volume changes with neurodegeneration and inflammation, as well as abnormalities in functional and structural connectivity. MRI arterial spin labeling allows for the quantification of regional cerebral blood flow, characteristically altered in Alzheimer's disease, diffuse Lewy-body disease, and the frontotemporal dementias. Positron emission tomography allows for the determination of regional metabolism, with similar abnormalities as flow, and for the measurement of β-amyloid and abnormal tau deposition in the brain, as well as regional inflammation. These instruments allow for the quantification in vivo of most of the pathologic features observed in disorders causing dementia. Importantly, they allow for the longitudinal study of these abnormalities, having revealed, for instance, that the deposition of β-amyloid in the brain can antecede by decades the onset of dementia. Thus, a therapeutic window has been opened and the efficacy of immunotherapies directed at removing β-amyloid from the brain of asymptomatic individuals is currently being tested. Tau and inflammation imaging, still in their infancy, combined with genomics, should provide powerful insights into these disorders and facilitate their treatment.

Is descriptive writing useful in the differential diagnosis of logopenic variant of primary progressive aphasia, Alzheimer's disease and mild cognitive impairment?

Current classification of primary progressive aphasia (PPA) encompasses three variants: non-fluent (nfvPPA), semantic (svPPA) and logopenic (lvPPA). Previously lvPPA was regarded as aphasic form of Alzheimer's disease (AD). However, not all patients with lvPPA phenotype present with AD pathology. Despite abundant literature on differentiation of lvPPA from svPPA and nfvPPA, studies comparing lvPPA with AD and mild cognitive impairment (MCI) are scarce. This study aimed at analyzing written descriptive output in lvPPA, AD and MCI. Thirty-five patients participated in the study: 9 with lvPPA, 13 with AD and 13 with MCI. Most aspects of writing performance were comparable in three groups. However, letter insertion errors appeared in 44% patients with lvPPA, while they were absent in AD and MCI. Patients with lvPPA used more verbs than patients with AD. Writing profile may complement other neuropsychological assessment results in the differential diagnosis of lvPPA. Letter insertion errors and frequent verb use may raise a query of lvPPA.

Childhood Learning Disabilities and Atypical Dementia: A Retrospective Chart Review

Objective

To further our understanding of the association between self-reported childhood learning disabilities (LDs) and atypical dementia phenotypes (Atypical Dementia), including logopenic primary progressive aphasia (L-PPA), Posterior Cortical Atrophy (PCA), and Dysexecutive-type Alzheimer’s Disease (AD).

Methods

This retrospective case series analysis of 678 comprehensive neuropsychological assessments compared rates of self-reported LD between dementia patients diagnosed with Typical AD and those diagnosed with Atypical Dementia. 105 cases with neuroimaging or CSF data available and at least one neurology follow-up were identified as having been diagnosed by the neuropsychologist with any form of neurodegenerative dementia. These cases were subject to a consensus diagnostic process among three dementia experts using validated clinical criteria for AD and PPA. LD was considered Probable if two or more statements consistent with prior LD were documented within the Social & Developmental History of the initial neuropsychological evaluation.

Results

85 subjects (Typical AD n=68, Atypical AD n=17) were included in the final analysis. In logistic regression models adjusted for age, gender, handedness, education and symptom duration, patients with Probable LD, compared to patients without Probable LD, were significantly more likely to be diagnosed with Atypical Dementia vs. Typical AD (OR 13.1, 95% CI 1.3-128.4). All three of the L-PPA cases reporting a childhood LD endorsed childhood difficulty with language. By contrast, both PCA cases reporting Probable childhood LD endorsed difficulty with attention and/or math.

Conclusions

In people who develop dementia, childhood LD may predispose to atypical phenotypes. Future studies are required to confirm whether atypical neurodevelopment predisposes to regional-specific neuropathology in AD and other dementias.