Dysexecutive versus amnestic Alzheimer disease subgroups: analysis of demographic, genetic, and vascular factors

Cognitive dispersion and its functional relevance in behavioral variant frontotemporal dementia and prodromal behavioral variant frontotemporal dementia

OBJECTIVE

Executive dysfunction is characteristic of behavioral variant frontotemporal dementia (bvFTD) but can be challenging to detect. Dispersion-based intraindividual variability (IIV-d) is hypothesized to reflect a sensitive index of executive dysfunction and has demonstrated relevance to functional decline but has not been evaluated in bvFTD.

METHOD

We report on 477 demographically matched participants (159 cognitively healthy [CH], 159 clinical Alzheimer's disease [AD], 159 clinical bvFTD/prodromal bvFTD) who completed the Uniform Data Set 3.0 Neuropsychological Battery. IIV-d was measured using the coefficient of variance (CoV; raw and demographically adjusted) across 12 Uniform Data Set 3.0 Neuropsychological Battery indicators and the informant-rated Functional Activities Questionnaire assessed daily functioning.

RESULTS

Analysis of covariance showed that participants in the bvFTD/prodromal bvFTD group exhibited higher raw and demographically adjusted CoV compared to CH participants, at a very large effect size (d = 1.28-1.47). Demographically adjusted (but not raw) CoV was lower in the bvFTD/prodromal bvFTD group than the AD group, though the effect size was small (d = .38). Both CoV metrics accurately differentiated the bvFTD/prodromal bvFTD and CH groups (areas under the curve = .84), but not bvFTD/prodromal bvFTD and AD groups (areas under the curve = .59). Regression analyses in the bvFTD/prodromal bvFTD group indicated that higher IIV-d on both metrics was associated with greater daily functioning impairment, over and above covariates.

CONCLUSIONS

Compared to healthy adults, individuals with bvFTD/prodromal bvFTD show greater levels of performance variability across a battery of neuropsychological measures, which interferes with everyday functioning. These data demonstrate the clinical utility and ecological validity of IIV-d in bvFTD/prodromal bvFTD, though these findings should be replicated in more diverse samples. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Association between perceived risk of Alzheimer's disease and related dementias and cognitive function among U.S. older adults

INTRODUCTION

The aim of the study was to assess factors associated with the perceived risk of developing Alzheimer's disease and related dementias (ADRD) and how the perceived risk of ADRD was related to cognitive function.

METHODS

We conducted a retrospective cohort study using 5 waves of data from the Health and Retirement Study (2012-2022) that included adults aged 65 years or older with no previous diagnosis of ADRD at baseline. Cognitive function was measured at baseline and over time using a summary score that included immediate/delayed word recall, serial 7's test, objective naming test, backwards counting, recall of the current date, and naming the president/vice-president (range = 0-35). Perceived risk of developing ADRD was categorized at baseline as "definitely not" (0% probability), "unlikely" (1-49%), "uncertain" (50%), and "more than likely" (>50-100%). Additional baseline measures included participants' sociodemographic background, psychosocial resources, health behaviors, physiological status, and healthcare utilization.

RESULTS

Of 1457 respondents (median age 74 [IQR = 69-80] and 59.8% women), individuals who perceived that they were "more than likely" to develop ADRD had more depressive symptoms and were more likely to be hospitalized in the past two years than individuals who indicated that it was "unlikely" they would develop ADRD. Alternatively, respondnets who perceived that they would "definitely not" develop ADRD were more likely to be non-Hispanic Black, less educated, and have lower income than individuals who indicated it was "unlikely" they would develop ADRD. Respondents who reported their risks of developing ADRD as "more than likely" (β = -2.10, P < 0.001) and "definitely not" (β = -1.50, P < 0.001) had the lowest levels of cognitive function; and the associations were explained in part by their socioeconomic, psychosocial, and health status.

CONCLUSIONS

Perceived risk of developing ADRD is associated with cognitive function. The (dis)concordance between individuals' perceived risk of ADRD and their cognitive function has important implications for increasing public awareness and developing interventions to prevent ADRD.

How Many Alzheimer-Perusini's Atypical Forms Do We Still Have to Discover?

Alzheimer-Perusini's (AD) disease represents the most spread dementia around the world and constitutes a serious problem for public health. It was first described by the two physicians from whom it took its name. Nowadays, we have extensively expanded our knowledge about this disease. Starting from a merely clinical and histopathologic description, we have now reached better molecular comprehension. For instance, we passed from an old conceptualization of the disease based on plaques and tangles to a more modern vision of mixed proteinopathy in a one-to-one relationship with an alteration of specific glial and neuronal phenotypes. However, no disease-modifying therapies are yet available. It is likely that the only way to find a few "magic bullets" is to deepen this aspect more and more until we are able to draw up specific molecular profiles for single AD cases. This review reports the most recent classifications of AD atypical variants in order to summarize all the clinical evidence using several discrimina (for example, post mortem neurofibrillary tangle density, cerebral atrophy, or FDG-PET studies). The better defined four atypical forms are posterior cortical atrophy (PCA), logopenic variant of primary progressive aphasia (LvPPA), behavioral/dysexecutive variant and AD with corticobasal degeneration (CBS). Moreover, we discuss the usefulness of such classifications before outlining the molecular-genetic aspects focusing on microglial activity or, more generally, immune system control of neuroinflammation and neurodegeneration.

Impact of dysexecutive syndrome in quality of life in Alzheimer disease: What we know now and where we are headed

Alzheimer's disease (AD) is a common form of dementia that leads to multiple repercussions in the patient's life. This condition's clinical characteristics include loss of memory, temporal and spatial disorientation, language or executive dysfunction, and subsequent decline of social function. Dysexecutive syndrome (DS), the second most frequent neuropsychological dysfunction in AD, affects multiple brain areas and causes cognitive, behavioral, and emotional difficulties. We aimed to analyze the association between DS and AD and elucidate possible lack of evidence that may urge further research on this theme. Especially when dealing with such a disabling disease, where new findings can directly imply a better prognosis.

Neuropathology-Independent Association Between APOE Genotype and Cognitive Decline Rate in the Normal Aging-Early Alzheimer Continuum

Background and Objectives

We previously found that the APOE genotype affects the rate of cognitive decline in mild-to-moderate Alzheimer disease (AD) dementia independently of its effects on AD neuropathologic changes (ADNC) and copathologies. In this study, we tested the hypothesis that the APOE alleles differentially affect the rate of cognitive decline at the normal aging-early AD continuum and that this association is independent of their effects on classical ADNC and copathologies.

Methods

We analyzed APOE associations with the cognitive trajectories (Clinical Dementia Rating scale Sum of Boxes [CDR-SOB] and Mini-Mental State Examination [MMSE]) of more than 1,000 individuals from a national clinicopathologic sample who had either no, mild (sparse neuritic plaques and the Braak neurofibrillary tangle [NFT] stage I/II), or intermediate (moderate neuritic plaques and the Braak NFT stage III/IV) ADNC levels at autopsy via 2 latent classes reverse-time longitudinal modeling.

Results

Carrying the APOEε4 allele was associated with a faster rate of cognitive decline by both CDR-SOB and MMSE relative to APOEε3 homozygotes. This association remained statistically significant after adjusting for ADNC severity, comorbid pathologies, and the effects of ADNC on the slope of cognitive decline. Our modeling strategy identified 2 latent classes in which APOEε4 carriers declined faster than APOEε3 homozygotes, with latent class 1 members representing slow decliners (CDR-SOB: 76.7% of individuals, 0.195 vs 0.146 points/y in APOEε4 vs APOEε3/ε3; MMSE: 88.6% of individuals, -0.303 vs -0.153 points/y in APOEε4 vs APOEε3/ε3), whereas latent class 2 members were fast decliners (CDR-SOB: 23.3% of participants, 1.536 vs 1.487 points/y in APOEε4 vs APOEε3/ε3; MMSE: 11.4% of participants, -2.538 vs -2.387 points/y in APOEε4 vs APOEε3/ε3). Compared with slow decliners, fast decliners were more likely to carry the APOEε4 allele, younger at initial visit and death, more impaired at initial and last visits, and more likely to have intermediate (vs none or mild) ADNC levels, as well as concurrent Lewy bodies and hippocampal sclerosis at autopsy.

Discussion

In a large national sample selected to represent the normal aging-early AD continuum, the APOEε4 allele is associated with a modest but statistically significant acceleration of the cognitive decline rate even after controlling for its effects on ADNC and comorbid pathologies.

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

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

Breakdown of specific functional brain networks in clinical variants of Alzheimer's disease

Alzheimer's disease (AD) is characterized by different clinical entities. Although AD phenotypes share a common molecular substrate (i.e., amyloid beta and tau accumulation), several clinicopathological differences exist. Brain functional networks might provide a macro-scale scaffolding to explain this heterogeneity. In this review, we summarize the evidence linking different large-scale functional network abnormalities to distinct AD phenotypes. Specifically, executive deficits in early-onset AD link with the dysfunction of networks that support sustained attention and executive functions. Posterior cortical atrophy relates to the breakdown of visual and dorsal attentional circuits, while the primary progressive aphasia variant of AD may be associated with the dysfunction of the left-lateralized language network. Additionally, network abnormalities might provide in vivo signatures for distinguishing proteinopathies that mimic AD, such as TAR DNA binding protein 43 related pathologies. These network differences vis-a-vis clinical syndromes are more evident in the earliest stage of AD. Finally, we discuss how these findings might pave the way for new tailored interventions targeting the most vulnerable brain circuit at the optimal time window to maximize clinical benefits.

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.

Race modifies default mode connectivity in Alzheimer's disease

Background

Older African Americans are more likely to develop Alzheimer's disease (AD) than older Caucasians, and this difference cannot be readily explained by cerebrovascular and socioeconomic factors alone. We previously showed that mild cognitive impairment and AD dementia were associated with attenuated increases in the cerebrospinal fluid (CSF) levels of total and phosphorylated tau in African Americans compared to Caucasians, even though there was no difference in beta-amyloid 1-42 level between the two races.

Methods

We extended our work by analyzing early functional magnetic resonance imaging (fMRI) biomarkers of the default mode network in older African Americans and Caucasians. We calculated connectivity between nodes of the regions belonging to the various default mode network subsystems and correlated these imaging biomarkers with non-imaging biomarkers implicated in AD (CSF amyloid, total tau, and cognitive performance).

Results

We found that race modifies the relationship between functional connectivity of default mode network subsystems and cognitive performance, tau, and amyloid levels.

Conclusion

These findings provide further support that race modifies the AD phenotypes downstream from cerebral amyloid deposition, and identifies key inter-subsystem connections for deep imaging and neuropathologic characterization.

Genetic data and cognitively defined late-onset Alzheimer's disease subgroups

Categorizing people with late-onset Alzheimer's disease into biologically coherent subgroups is important for personalized medicine. We evaluated data from five studies (total n = 4050, of whom 2431 had genome-wide single-nucleotide polymorphism (SNP) data). We assigned people to cognitively defined subgroups on the basis of relative performance in memory, executive functioning, visuospatial functioning, and language at the time of Alzheimer's disease diagnosis. We compared genotype frequencies for each subgroup to those from cognitively normal elderly controls. We focused on APOE and on SNPs with p < 10^-5 and odds ratios more extreme than those previously reported for Alzheimer's disease (<0.77 or >1.30). There was substantial variation across studies in the proportions of people in each subgroup. In each study, higher proportions of people with isolated substantial relative memory impairment had ≥1 APOE ε4 allele than any other subgroup (overall p = 1.5 × 10^-27). Across subgroups, there were 33 novel suggestive loci across the genome with p < 10^-5 and an extreme OR compared to controls, of which none had statistical evidence of heterogeneity and 30 had ORs in the same direction across all datasets. These data support the biological coherence of cognitively defined subgroups and nominate novel genetic loci.

Cognitive Function and Atrial Fibrillation: From the Strength of Relationship to the Dark Side of Prevention. Is There a Contribution from Sinus Rhythm Restoration and Maintenance?

Atrial fibrillation (AF) is the most common chronic cardiac arrhythmia with an increasing prevalence over time mainly because of population aging. It is well established that the presence of AF increases the risk of stroke, heart failure, sudden death, and cardiovascular morbidity. In the last two decades several reports have shown an association between AF and cognitive function, ranging from impairment to dementia. Ischemic stroke linked to AF is a well-known risk factor and predictor of cognitive decline. In this clinical scenario, the risk of stroke might be reduced by oral anticoagulation. However, recent data suggest that AF may be a predictor of cognitive impairment and dementia also in the absence of stroke. Cerebral hypoperfusion, reduced brain volume, microbleeds, white matter hyperintensity, neuroinflammation, and genetic factors have been considered as potential mechanisms involved in the pathogenesis of AF-related cognitive dysfunction. However, a cause-effect relationship remains still controversial. Consequently, no therapeutic strategies are available to prevent AF-related cognitive decline in stroke-free patients. This review will analyze the potential mechanisms leading to cognitive dysfunction in AF patients and examine the available data on the impact of a sinus rhythm restoration and maintenance strategy in reducing the risk of cognitive decline.

Cognitive heterogeneity in probable Alzheimer disease: Clinical and neuropathologic features

OBJECTIVE

To identify heterogeneity in cognitive profiles of patients with probable Alzheimer disease (AD) who have mild to moderate dementia and satisfy inclusion and exclusion criteria for a typical AD clinical trial, and to determine whether cognitive profiles are systematically related to the clinical course and neuropathologic features of the disease.

METHODS

Neuropsychological test data from patients with mild to moderate probable AD (n = 4,711) were obtained from the National Alzheimer's Coordinating Center. Inclusion and exclusion criteria usually used in AD clinical trials were applied. Principal component analysis and model-based clustering were used to identify cognitive profiles in a subset of patients with autopsy-verified AD (n = 800) and validated in the overall (nonautopsy) sample and an independent cohort with similar test data. Relationships between cognitive profile, clinical characteristics, and rate of decline were examined with mixed-effects models.

RESULTS

In the autopsy-confirmed sample, 79.6% of patients had a typical AD cognitive profile (greater impairment of episodic memory than other cognitive functions), and 20.4% had an atypical profile (comparable impairment across cognitive domains). Similar results were obtained in the overall (typical 79.8%, atypical 20.2%) and validation (typical 71.8%, atypical 28.2%) samples. Atypicality was associated with younger age, male sex, lower probability of APOE ε4, less severe global dementia, higher depression scores, lower Braak stage at autopsy, and slower cognitive decline.

CONCLUSION

We can reliably identify distinct cognitive profiles among patients with clinically diagnosed probable AD that are associated with tangle pathology and with different rates of decline. This may have implications for clinical trials in AD, especially therapies targeting tau.

Independent effects of white matter hyperintensities on cognitive, neuropsychiatric, and functional decline: a longitudinal investigation using the National Alzheimer's Coordinating Center Uniform Data Set

BACKGROUND

Longitudinal investigations are needed to improve understanding of the contributions of cerebral small vessel disease to the clinical manifestation of Alzheimer's disease, particularly in the early disease stages. This study leveraged the National Alzheimer's Coordinating Center Uniform Data Set to longitudinally examine the association between white matter hyperintensities and neuropsychological, neuropsychiatric, and functional decline among participants with normal cognition.

METHODS

The sample included 465 participants from the National Alzheimer's Coordinating Center Uniform Data Set who had quantitated volume of white matter hyperintensities from fluid-attenuated inversion recovery MRI, had normal cognition at the time of their MRI, and were administered the National Alzheimer's Coordinating Center Uniform Data Set neuropsychological test battery within 1 year of study evaluation and had at least two post-MRI time points of clinical data. Neuropsychiatric status was assessed by the Geriatric Depression Scale-15 and Neuropsychiatric Inventory-Questionnaire. Clinical Dementia Rating Sum of Boxes defined functional status. For participants subsequently diagnosed with mild cognitive impairment (MCI) or dementia, their impairment must have been attributed to Alzheimer's disease (AD) to evaluate the relationships between WMH and the clinical presentation of AD.

RESULTS

Of the 465 participants, 56 converted to MCI or AD dementia (average follow-up = 5 years). Among the 465 participants, generalized estimating equations controlling for age, sex, race, education, APOE ε4, and total brain and hippocampal volume showed that higher baseline log-white matter hyperintensities predicted accelerated decline on the following neuropsychological tests in rank order of effect size: Trails B (p < 0.01), Digit Symbol Coding (p < 0.01), Logical Memory Immediate Recall (p = 0.02), Trail Making A (p < 0.01), and Semantic Fluency (p < 0.01). White matter hyperintensities predicted increases in Clinical Dementia Rating Sum of Boxes (p < 0.01) and Geriatric Depression Scale-15 scores (p = 0.01). Effect sizes were comparable to total brain and hippocampal volume. White matter hyperintensities did not predict diagnostic conversion. All effects also remained after including individuals with non-AD suspected etiologies for those who converted to MCI or dementia.

CONCLUSIONS

In this baseline cognitively normal sample, greater white matter hyperintensities were associated with accelerated cognitive, neuropsychiatric, and functional decline independent of traditional risk factors and MRI biomarkers for Alzheimer's disease.

A Case with Early Onset Alzheimer's Disease, Frontotemporal Hypometabolism, ApoE Genotype ɛ4/ɛ4 and C9ORF72 Intermediate Expansion: A Treviso Dementia (TREDEM) Registry Case Report

We report the case of a woman firstly referred to our Memory Clinic at the age of 61, following the development of cognitive complaints and difficulties in sustained attention. The investigation that was performed showed: predominant executive dysfunctions at the neuropsychological evaluation, with mild, partial and stable involvement of the memory domain; cortical and subcortical atrophy with well-preserved hippocampal structures at MRI; marked fronto-temporal and moderate parietal hypometabolism from 18F-FDG PET study with a sparing of the posterior cingulate and precuneus; positivity of amyloid-β at 18F-Flutemetamol PET; an hexanucleotide intermediate repeats expansion of C9ORF72 gene (12//38 repeats) and ApoE genotype ɛ4/ɛ4. The patient was diagnosed with probable early onset frontal variant of Alzheimer's disease (AD), presenting with a major executive function impairment. The lack of specific areas of brain atrophy, as well as the failure to meet the clinical criteria for any frontotemporal dementia, drove us to perform the aforementioned investigations, which yielded our final diagnosis. The present case highlights the need to take into consideration a diagnosis of frontal variant of AD when the metabolic and the clinical picture are somehow dissonant.

Perspectives on ethnic and racial disparities in Alzheimer's disease and related dementias: Update and areas of immediate need

Alzheimer's disease and related dementias (ADRDs) are a global crisis facing the aging population and society as a whole. With the numbers of people with ADRDs predicted to rise dramatically across the world, the scientific community can no longer neglect the need for research focusing on ADRDs among underrepresented ethnoracial diverse groups. The Alzheimer's Association International Society to Advance Alzheimer's Research and Treatment (ISTAART; alz.org/ISTAART) comprises a number of professional interest areas (PIAs), each focusing on a major scientific area associated with ADRDs. We leverage the expertise of the existing international cadre of ISTAART scientists and experts to synthesize a cross-PIA white paper that provides both a concise "state-of-the-science" report of ethnoracial factors across PIA foci and updated recommendations to address immediate needs to advance ADRD science across ethnoracial populations.

Effects of APOE ε4 on neuroimaging, cerebrospinal fluid biomarkers, and cognition in prodromal Alzheimer's disease

Apolipoprotein (APOE) ε4 is a major genetic risk factor for Alzheimer's disease (AD), but its importance for the clinical and biological heterogeneity in AD is unclear, particularly at the prodromal stage. We analyzed 151 prodromal AD patients (44 APOE ε4-negative and 107 APOE ε4-positive) from the BioFINDER study. We tested cognition, 18F-flutemetamol β-amyloid (Aβ) positron emission tomography, cerebrospinal fluid biomarkers of Aβ, tau and neurodegeneration, and magnetic resonance imaging of white matter pathology and brain structure. Despite having similar cortical Aβ-load and baseline global cognition (mini mental state examination), APOE ε4-negative prodromal AD had more nonamnestic cognitive impairment, higher cerebrospinal fluid levels of Aβ-peptides and neuronal injury biomarkers, more white matter pathology, more cortical atrophy, and faster decline of mini mental state examination, compared to APOE ε4-positive prodromal AD. The absence of APOE ε4 is associated with an atypical phenotype of prodromal AD. This suggests that APOE ε4 may impact both the diagnostics of AD in early stages and potentially also effects of disease-modifying treatments.

Cognition and anatomy of adult Niemann-Pick disease type C: Insights for the Alzheimer field

Niemann-Pick disease type C (NPC) is a rare lysosomal storage disorder causing an intracellular lipid trafficking defect and varying damage to the spleen, liver, and central nervous system. The adult form, representing approximately 20% of the cases, is associated with progressive cognitive decline. Intriguingly, brains of adult NPC patients exhibit neurofibrillary tangles, a characteristic hallmark of Alzheimer's disease (AD). However, the cognitive, psychiatric, and neuropathological features of adult NPC and their relation to AD have yet to be explored. We systematically reviewed the literature on adult NPC with a particular focus on cognitive and neuroanatomical abnormalities. The careful study of cognition in adult NPC allows drawing critical insights in our understanding of the pathophysiology of AD as well as normal cognition.

The executive prominent/memory prominent spectrum in Alzheimer's disease is highly heritable

Late-onset Alzheimer's disease (LOAD) can present heterogeneously, with several subtypes recognized, including dysexecutive AD. One way to identify people with dysexecutive AD is to consider the difference between memory and executive functioning, which we refer to as the executive prominent/memory prominent spectrum. We aimed to determine if this spectrum was heritable. We used neuropsychological and genetic data from people with mild LOAD (Clinical Dementia Rating 0.5 or 1.0) from the National Alzheimer's Coordinating Center and the Alzheimer's Disease Neuroimaging Initiative. We cocalibrated the neuropsychological data to obtain executive functioning and memory scores and used their difference as a continuous phenotype to calculate its heritability overall and by chromosome. Narrow-sense heritability of the difference between memory and executive functioning scores was 0.68 (standard error 0.12). Single nucleotide polymorphisms on chromosomes 1, 2, 4, 11, 12, and 18 explained the largest fraction of phenotypic variance, with signals from each chromosome accounting for 5%-7%. The chromosomal pattern of heritability differed substantially from that of LOAD itself.

The behavioural/dysexecutive variant of Alzheimer's disease: clinical, neuroimaging and pathological features

A 'frontal variant of Alzheimer's disease' has been described in patients with predominant behavioural or dysexecutive deficits caused by Alzheimer's disease pathology. The description of this rare Alzheimer's disease phenotype has been limited to case reports and small series, and many clinical, neuroimaging and neuropathological characteristics are not well understood. In this retrospective study, we included 55 patients with Alzheimer's disease with a behavioural-predominant presentation (behavioural Alzheimer's disease) and a neuropathological diagnosis of high-likelihood Alzheimer's disease (n = 17) and/or biomarker evidence of Alzheimer's disease pathology (n = 44). In addition, we included 29 patients with autopsy/biomarker-defined Alzheimer's disease with a dysexecutive-predominant syndrome (dysexecutive Alzheimer's disease). We performed structured chart reviews to ascertain clinical features. First symptoms were more often cognitive (behavioural Alzheimer's disease: 53%; dysexecutive Alzheimer's disease: 83%) than behavioural (behavioural Alzheimer's disease: 25%; dysexecutive Alzheimer's disease: 3%). Apathy was the most common behavioural feature, while hyperorality and perseverative/compulsive behaviours were less prevalent. Fifty-two per cent of patients with behavioural Alzheimer's disease met diagnostic criteria for possible behavioural-variant frontotemporal dementia. Overlap between behavioural and dysexecutive Alzheimer's disease was modest (9/75 patients). Sixty per cent of patients with behavioural Alzheimer's disease and 40% of those with the dysexecutive syndrome carried at least one APOE ε4 allele. We also compared neuropsychological test performance and brain atrophy (applying voxel-based morphometry) with matched autopsy/biomarker-defined typical (amnestic-predominant) Alzheimer's disease (typical Alzheimer's disease, n = 58), autopsy-confirmed/Alzheimer's disease biomarker-negative behavioural variant frontotemporal dementia (n = 59), and controls (n = 61). Patients with behavioural Alzheimer's disease showed worse memory scores than behavioural variant frontotemporal dementia and did not differ from typical Alzheimer's disease, while executive function composite scores were lower compared to behavioural variant frontotemporal dementia and typical Alzheimer's disease. Voxel-wise contrasts between behavioural and dysexecutive Alzheimer's disease patients and controls revealed marked atrophy in bilateral temporoparietal regions and only limited atrophy in the frontal cortex. In direct comparison with behavioural and those with dysexecutive Alzheimer's disease, patients with behavioural variant frontotemporal dementia showed more frontal atrophy and less posterior involvement, whereas patients with typical Alzheimer's disease were slightly more affected posteriorly and showed less frontal atrophy (P < 0.001 uncorrected). Among 24 autopsied behavioural Alzheimer's disease/dysexecutive Alzheimer's disease patients, only two had primary co-morbid FTD-spectrum pathology (progressive supranuclear palsy). In conclusion, behavioural Alzheimer's disease presentations are characterized by a milder and more restricted behavioural profile than in behavioural variant frontotemporal dementia, co-occurrence of memory dysfunction and high APOE ε4 prevalence. Dysexecutive Alzheimer's disease presented as a primarily cognitive phenotype with minimal behavioural abnormalities and intermediate APOE ε4 prevalence. Both behavioural Alzheimer's disease and dysexecutive Alzheimer's disease presentations are distinguished by temporoparietal-predominant atrophy. Based on the relative sparing of frontal grey matter, we propose to redefine these clinical syndromes as 'the behavioural/dysexecutive variant of Alzheimer's disease' rather than frontal variant Alzheimer's disease. Further work is needed to determine whether behavioural and dysexecutive-predominant presentations of Alzheimer's disease represent distinct phenotypes or a single continuum.

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.

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.

Untimed Design Fluency in Aging and Alzheimer's Disease: Psychometrics and Normative Data

Design fluency tests, commonly used in both clinical and research contexts to evaluate nonverbal concept generation, have the potential to offer useful information in the differentiation of healthy versus pathological aging. Although normative data for older adults (OAs) are available for multiple timed versions of this test, similar data have been unavailable for a previously published untimed test, the Graphic Pattern Generation Test (GPG). Time constraints common to almost all of the available design fluency tests may cloud interpretation of higher-level executive abilities-for example, in individuals with slow processing speed. The current study examined the psychometric properties of the GPG and presents normative data in a sample of 167 healthy OAs and 110 individuals diagnosed with Alzheimer's disease (AD). Results suggest that a brief version of the GPG can be administered reliably and that this short form has high test-retest and interrater reliability. Number of perseverations was higher in individuals with AD as compared with OAs. A cutoff score of 4 or more perseverations showed a moderate degree of sensitivity (76%) and specificity (37%) in distinguishing individuals with AD and OAs. Finally, perseverations were associated with nonmemory indexes, thereby underscoring the nonverbal nature of this error in OAs and individuals with AD.

Different demographic, genetic, and longitudinal traits in language versus memory Alzheimer's subgroups

The study's objective was to compare demographics, APOE genotypes, and rate of rise over time in functional impairment in neuropsychologically defined language, typical, and memory subgroups of clinical Alzheimer's disease (AD). 1,368 participants from the National Alzheimer's Coordinating Center database with a diagnosis of probable AD (CDR 0.5-1.0) were included. A language subgroup (n = 229) was defined as having language performance >1 SD worse than memory performance. A memory subgroup (n = 213) was defined as having memory performance >1 SD worse than language performance. A typical subgroup (n = 926) was defined as having a difference in language and memory performance of <1 SD. Compared with the memory subgroup, the language subgroup was 3.7 years older and more frequently self-identified as African American (OR = 3.69). Under a dominant genetic model, the language subgroup had smaller odds of carrying at least one APOEε4 allele relative to the memory subgroup. While this difference was present for all ages, it was more striking at a younger age (OR = 0.19 for youngest tertile; OR = 0.52 for oldest tertile). Compared with the memory subgroup, the language subgroup rose 35% faster on the Functional Assessment Questionnaire and 44% faster on CDR sum of boxes over time. Among a subset of participants who underwent autopsy (n = 98), the language, memory, and typical subgroups were equally likely to have an AD pathologic diagnosis, suggesting that variation in non-AD pathologies across subtypes did not lead to the observed differences. The study demonstrates that a language subgroup of AD has different demographics, genetic profile, and disease course in addition to cognitive phenotype.

Faster cognitive and functional decline in Dysexecutive versus amnestic Alzheimer's subgroups: a longitudinal analysis of the National Alzheimer's Coordinating Center (NACC) database

OBJECTIVE

To compare the rate of cognitive and functional decline in dysexecutive, typical and amnestic subgroups of Alzheimer's disease.

METHODS

943 participants from the National Alzheimer's Coordinating Center (NACC) database who had a diagnosis of probable AD were followed for a mean of 2.3 years. A dysexecutive subgroup (n = 165) was defined as having executive performance >1.5 SD worse than memory performance, an amnestic subgroup (n = 157) was defined as having memory performance >1.5 SD worse than executive performance and a typical subgroup (n = 621) was defined as having a difference in executive and memory performance of <1.5 SD. Generalized estimating equations (GEE) were used to model decline on the Folstein Mini Mental Status Exam (MMSE), rise on the Clinical Dementia Rating (CDR) sum of boxes and rise on the total Functional Assessment Questionnaire (FAQ).

RESULTS

Compared with the amnestic subgroup, the dysexecutive subgroup declined 2.2X faster on the Folstein MMSE (p<.001), rose 42% faster on the CDR sum of boxes (p = .03) and rose 33% faster on the total FAQ (p = .01). Rate of change for the typical subgroup fell between that of the amnestic and dysexecutive subgroups for the MMSE, CDR sum of boxes and total FAQ. Among a subset of participants (n = 129) who underwent autopsy, the dysexecutive, amnestic and typical subgroups did not differ in odds of having an AD pathologic diagnosis, suggesting that variation in non-AD pathologies across subtypes did not lead to the observed differences.

CONCLUSIONS

A dysexecutive subgroup of AD has a unique disease course in addition to cognitive phenotype.

Language, executive function and social cognition in the diagnosis of frontotemporal dementia syndromes

Frontotemporal dementia (FTD) represents a spectrum of non-Alzheimer's degenerative conditions associated with focal atrophy of the frontal and/or temporal lobes. Frontal and temporal regions of the brain have been shown to be strongly involved in executive function, social cognition and language processing and, thus, deficits in these domains are frequently seen in patients with FTD or may even be hallmarks of a specific FTD subtype (i.e. relatively selective and progressive language impairment in primary progressive aphasia). In this review we have attempted to delineate how language, executive function, and social cognition may contribute to the diagnosis of FTD syndromes, namely the behavioural variant FTD as well as the language variants of FTD including the three subtypes of primary progressive aphasia (PPA): non-fluent/agrammatic, semantic and logopenic. This review also addresses the extent to which deficits in these cognitive areas contribute to the differential diagnosis of FTD versus Alzheimer's disease (AD). Finally, early clinical determinants of pathology are briefly discussed and contemporary challenges to the diagnosis of FTD are presented.