Citations

Background: The hippocampus and temporal lobe are atrophic in typical amnestic Alzheimer’s disease (tAD) and are used as imaging biomarkers in treatment trials. However, a better understanding of how temporal structures differ across atypical AD phenotypes and relate to cognition is needed. Objective: Our goal was to compare temporal lobe regions between tAD and two atypical AD phenotypes (logopenic progressive aphasia (LPA) and posterior cortical atrophy (PCA)), and assess cognitive associations. Methods: We age and gender-matched 77 tAD participants to 50 LPA and 27 PCA participants, all of which were amyloid-positive. We used linear mixed-effects models to compare FreeSurfer-derived hippocampal volumes and cortical thickness of entorhinal, inferior and middle temporal, and fusiform gyri, and to assess relationships between imaging and memory, naming, and visuospatial function across and within AD phenotype. Results: Hippocampal volume and entorhinal thickness were smaller bilaterally in tAD than LPA and PCA. PCA showed greater right inferior temporal and bilateral fusiform thinning and LPA showed greater left middle and inferior temporal and left fusiform thinning. Atypical AD phenotypes differed with greater right hemisphere thinning in PCA and greater left hemisphere thinning in LPA. Verbal and visual memory related most strongly to hippocampal volume; naming related to left temporal thickness; and visuospatial related to bilateral fusiform thickness. Fewer associations remained when examined within AD group. Conclusion: Atypical AD phenotypes are associated with greater thinning of lateral temporal structures, with relative sparing of medial temporal lobe, compared to tAD. These findings may have implications for future clinical trials in AD.

AbstractIntroductionTo address the need for remote assessments of cognitive decline and dementia, we developed and administered electronic versions of the Clinical Dementia Rating (CDR®) and the Financial Capacity Instrument‐Short Form (FCI‐SF) (F‐CAP®), called the eCDR and eFCI, respectively.MethodsThe CDR and FCI‐SF were adapted for remote, unsupervised, online use based on item response analysis of the standard instruments. Participants completed the eCDR and eFCI first in clinic, and then at home within 2 weeks.ResultsOf the 243 enrolled participants, 179 (73%) cognitively unimpaired (CU), 50 (21%) with mild cognitive impairment (MCI) or dementia, and 14 (6%) with an unknown diagnosis, 84% and 85% of them successfully completed the eCDR and eFCI, respectively, at home.DiscussionThese results show initial feasibility in developing and administering online instruments to remotely assess and monitor cognitive decline along the CU to MCI/very mild dementia continuum. Validation is an important next step.

Abstract Introduction The aim of this study was to develop a conditional normative model for Rey's Auditory Verbal Learning Test (AVLT) that accounts for practice effects. Methods In our normative sample, robust conditional norms were derived from 1001 cognitively unimpaired (CU) adults ages 50 to 89 who completed the AVLT up to eight times. Linear mixed‐effects models adjusted for baseline performance, prior test exposures, time, demographics, and interaction terms. In our preliminary validation, mean performance on conditional and typical normative scores across two to four completed follow‐up tests in preclinical Alzheimer's disease participants at baseline with positive amyloid and tau positron emission ( n = 27 CU amyloid [A]+tau[T]+) was compared to biomarker negative individuals ( n = 269 CU A–T–). Results AVLT performance using typical norms did not differ across A+T+ and A–T– groups. Conditional norms z‐scores were lower in the A+T+ relative to the A–T– group for 30‐minute recall ( P = .033) and sum of trials ( P = .030). Discussion Conditional normative methods that account for practice effects show promise for identifying longitudinal cognitive decline.

Background: Brain accumulation of amyloid-β is a hallmark event in Alzheimer’s disease (AD) whose underlying mechanisms are incompletely understood. Case-control genome-wide association studies have implicated numerous genetic variants in risk of clinically diagnosed AD dementia. Objective: To test for associations between case-control AD risk variants and amyloid PET burden in older adults, and to assess whether a polygenic measure encompassing these factors would account for a large proportion of the unexplained variance in amyloid PET levels in the wider population. Methods: We analyzed data from the Mayo Clinic Study of Aging (MCSA) and the Alzheimer’s Disease Neuroimaging Initiative (ADNI). Global cortical amyloid PET burden was the primary outcome. The 38 gene variants from Wightman et al. (2021) were analyzed as predictors, with PRSice-2 used to assess the collective phenotypic variance explained. Results: Known AD risk variants in APOE, PICALM, CR1, and CLU were associated with amyloid PET levels. In aggregate, the AD risk variants were strongly associated with amyloid PET levels in the MCSA ( p = 1.51×10 –50 ) and ADNI ( p = 3.21×10 –64 ). However, in both cohorts the non- APOE variants uniquely contributed only modestly (MCSA = 2.1%, ADNI = 4.4%) to explaining variation in amyloid PET levels. Conclusion: Additional case-control AD risk variants added only modestly to APOE in accounting for individual variation in amyloid PET burden, results which were consistent across independent cohorts with distinct recruitment strategies and subject characteristics. Our findings suggest that advancing precision medicine for dementia may require integration of strategies complementing case-control approaches, including biomarker-specific genetic associations, gene-by-environment interactions, and markers of disease progression and heterogeneity.

AbstractIntroductionEpidemiological studies report an association between traumatic brain injury (TBI) and post‐traumatic stress disorder (PTSD) and clinically diagnosed Alzheimer's disease (AD). We examined the association between TBI/PTSD and biomarker‐defined AD.MethodsWe identified 289 non‐demented veterans with TBI and/or PTSD and controls who underwent clinical evaluation, cerebrospinal fluid (CSF) collection, magnetic resonance imaging (MRI), amyloid beta (Aβ) and tau positron emission tomography, and apolipoprotein E testing. Participants were followed for up to 5.2 years.ResultsExposure groups (TBI, PTSD, and TBI + PTSD) had higher prevalence of mild cognitive impairment (MCI: P < .0001) and worse Mini‐Mental State Examination scores (PTSD: P = .008; TBI & PTSD: P = .009) than controls. There were no significant differences in other cognitive scores, MRI volumes, Aβ or tau accumulation, or in most longitudinal measures.DiscussionTBI and/or PTSD were not associated with elevated AD biomarkers. The poorer cognitive status of exposed veterans may be due to other comorbid pathologies.

AbstractBackground and purposeAutoimmune encephalitis (AE) is a potentially treatable cause of rapidly progressive dementia that may mimic Creutzfeldt–Jakob disease (CJD). Alzheimer disease (AD) cerebrospinal fluid (CSF) biomarkers may discriminate CJD from AD, but utility in discriminating CJD and AE is unclear. This study compared AD CSF biomarkers in CJD and AE.MethodsPatients with probable or definite CJD and probable or definite AE who underwent Roche Elecsys AD CSF biomarker testing at Mayo Clinic from March 2020 through April 2021 were included. Total‐tau, phosphorylated181 tau and amyloid‐β42 levels were compared.ResultsOf 11 CJD cases, four were autopsy proven; the rest had positive real‐time quaking‐induced conversion testing. Disease‐associated autoantibodies were detected in 8/15 cases of AE: leucine‐rich glioma‐inactivated 1 and neuronal intermediate filaments (two cases each), and N‐methyl‐d‐aspartate receptor, contactin‐associated protein‐like 2, dipeptidyl‐peptidase‐like protein 6 and immunoglobulin‐like cell adhesion molecule IgLON family member 5. Total‐tau provided excellent discrimination between CJD and AE in a univariate model (odds ratio 1.46 per 100 pg/ml, 95% confidence interval 1.17–2.11, p < 0.05, c = 0.93). Total‐tau was elevated in 91% of CJD cases (median > 1300, range 236–>1300 pg/ml), of which 55% were above the limit of assay measurement (>1300 pg/ml). Total‐tau was elevated in 20% of AE cases (median 158, range 80–>1300 pg/ml).ConclusionTotal‐tau was greater in CJD than AE. Given that amyloid‐β42 and phosphorylated181 tau were comparable, the ratio differences were probably driven by elevated total‐tau in CJD. This study supports the role for AD biomarker testing in patients with rapidly progressive dementia.

Dementia is one of the most prevalent health problems in the aging population. Despite the significant number of people affected, dementia diagnoses are often significantly delayed, missing opportunities to maximize life quality. Early identification of older adults at high risk for dementia may help to maximize current quality of life and to improve planning for future health needs in dementia patients. However, most existing risk prediction models predominantly use static variables, not considering temporal patterns of health status. This study used an attention-based time-aware model to predict incident dementia that incorporated longitudinal temporal health conditions. The predictive performance of the time-aware model was compared with three traditional models using static variables and demonstrated higher predictive power.

AbstractIntroductionWe investigated the association of the area deprivation index (ADI) with cognitive decline, mild cognitive impairment (MCI), and dementia in older adults (≥50 years old). ADI is a neighborhood socioeconomic disadvantage measure assessed at the census block group level.MethodsThe study included 4699 participants, initially without dementia, with available ADI values for 2015 and at least one study visit in 2008 through 2018. Using logistic regression and Cox proportional hazards models with age as the time scale, we assessed the odds for MCI and the risk for dementia, respectively.ResultsIn cognitively unimpaired (CU) adults at baseline, the risk for progression to dementia increased for every decile increase in the ADI state ranking (hazard ratio = 1.06, 95% confidence interval (1.01–1.11), P = .01). Higher ADI values were associated with subtly faster cognitive decline.DiscussionIn older CU adults, higher baseline neighborhood socioeconomic deprivation levels were associated with progression to dementia and slightly faster cognitive decline.Highlights The study used area deprivation index, a composite freely available neighborhood deprivation measure. Higher levels of neighborhood deprivation were associated with greater mild cognitive impairment odds. Higher neighborhood deprivation levels were associated with higher dementia risk.

Abstract Introduction We have previously shown that older adults with excessive daytime sleepiness (EDS) appear to be more vulnerable to longitudinal amyloid PET accumulation before the onset of the dementia. It remains unclear whether this vulnerability is specific to amyloid or extends to other biomarkers of Alzheimer’s disease pathology, or axonal integrity and inflammation, which can also contribute to neurodegeneration and cognitive changes. Methods For this cross-sectional analysis, we identified 260 cognitively unimpaired adults (&gt;60 years old) without neurologic disorder who underwent CSF quantification of AD biomarkers (CSF Aβ-42, p-tau181, p-tau217) along with at least one other biomarker of interest (neurofilament light chain [NfL], IL-6, IL-10, and TNF-α) from the Mayo Clinic Study of Aging – a longitudinal population-based cohort in Olmsted County, Minnesota. CSF biomarkers were available in 251-260 individuals, depending on the biomarker. We fit linear regression models to assess whether the CSF biomarkers were associated with sleepiness as measured by the Epworth Sleepiness Scale (ESS), after controlling for age, sex, APOE4 genotype, BMI, hypertension, dyslipidemia, and OSA diagnosis (by chart review). Results Higher ESS scores were independently associated with higher CSF IL-6 and NfL, but not with the other biomarkers in the whole sample. For every single-point increase in the ESS score, there was a .008 ([95% CI .001-.016], p=0.033) increase in the log of IL-6 and .01 ([95% CI .002-.018], p=0.016) increase in the log of NfL. A sensitivity analysis showed a correlation between ESS scores and log of p-tau/Aβ-42 ratio only in participants with abnormal ratio (&gt;0.023), after controlling for APOE4 (partial r=.27, p=039). Conclusion Our results corroborate previous literature suggesting that higher inflammatory milieu reflected by increased CSF IL-6 is associated with sleepiness. The association between NfL and sleepiness suggests that sleepiness may be related to disturbed connectivity due to axonal damage. Alternatively, NfL may be a surrogate of active axonal injury associated with more disrupted sleep. A correlation between sleepiness and CSF p-tau/ab-42 ratio was only seen in patients with abnormal ratio, suggesting a stronger association between sleepiness and AD pathology as the disease progresses, possibly because AD pathology worsens sleep quality and/or vice-versa. Support (If Any) NIH/NIA

AbstractThe extent to which the pathophysiology of autosomal dominant Alzheimer's disease corresponds to the pathophysiology of ‘sporadic’ late onset Alzheimer's disease is unknown, thus limiting the extrapolation of study findings and clinical trial results in autosomal dominant Alzheimer's disease to late onset Alzheimer's disease.We compared brain MRI and amyloid PET data, as well as CSF concentrations of amyloid-β42, amyloid-β40, tau and tau phosphorylated at position 181, in 292 carriers of pathogenic variants for Alzheimer's disease from the Dominantly Inherited Alzheimer Network, with corresponding data from 559 participants from the Alzheimer’s Disease Neuroimaging Initiative. Imaging data and CSF samples were reprocessed as appropriate to guarantee uniform pipelines and assays. Data analyses yielded rates of change before and after symptomatic onset of Alzheimer's disease, allowing the alignment of the ∼30-year age difference between the cohorts on a clinically meaningful anchor point, namely the participant age at symptomatic onset.Biomarker profiles were similar for both autosomal dominant Alzheimer's disease and late onset Alzheimer's disease. Both groups demonstrated accelerated rates of decline in cognitive performance and in regional brain volume loss after symptomatic onset. Although amyloid burden accumulation as determined by PET was greater after symptomatic onset in autosomal dominant Alzheimer's disease than in late onset Alzheimer's disease participants, CSF assays of amyloid-β42, amyloid-β40, tau and p-tau181 were largely overlapping in both groups. Rates of change in cognitive performance and hippocampal volume loss after symptomatic onset were more aggressive for autosomal dominant Alzheimer's disease participants.These findings suggest a similar pathophysiology of autosomal dominant Alzheimer's disease and late onset Alzheimer's disease, supporting a shared pathobiological construct.