👤 Phoebe Scollard

The APOE-ε4 allele is the strongest genetic risk factor for late-onset Alzheimer's disease. However, APOE-ε4 is not deterministic, highlighting the need to identify additional genetic and environmental factors. APOE-ε4 has been linked to accelerated cognitive decline, so we sought to investigate genetic factors that modify APOE-ε4-associated cognitive decline. We conduct cross-ancestry APOE-ε4-stratified and interaction GWAS using harmonized cognitive data from 32,778 participants, including 29,354 non-Hispanic White and 3,424 non-Hispanic Black individuals. Our primary outcome is late-life cognition, measured using harmonized composite scores for memory, executive function, and language, modeled as continuous traits reflecting both normative cognitive aging and disease-related decline. We identify two genome-wide significant loci in APOE-ε4 carriers, reaching genome-wide significance for executive function. These loci also demonstrate nominal associations across the other domains, suggesting broad effects on cognition. In non-carriers, we identify a genome-wide significant association at ITGB8 restricted to executive function, and another locus associated with language. We further link these loci to SEMA6D, GRIN3A, and ITGB8 through expression and methylation databases. Post-GWAS analyses implicate additional genes including SLCO1A2, and DNAH11. Genetic correlation analyses reveal differences by APOE-ε4 status for immune-related traits, suggesting immune-related predispositions may exacerbate cognitive risk in APOE-ε4 carriers. Show less

BackgroundOthers have examined heterogeneity in Alzheimer's disease (AD); however, few have used longitudinal data while accounting for variation in disease stage. We used latent classes to model heterogeneity in the trajectories of three cognitive domains (memory, language, and executive functioning) starting at AD dementia diagnosis.ObjectiveOur aim was to describe the patterns of heterogeneity in cognitive decline across cognitive domains during the course of AD and to contextualize our findings by assessing associations with demographic factors and neuropathological measures.MethodsWe used cognitive data from the Religious Orders Study, the Rush Memory and Aging Project, and the Minority Aging Research Study in a multi-dimensional joint latent class mixed model, which allowed us to estimate cognitive trajectories that varied across cognitive domains and latent classes. We accounted for the uncertainty in latent class assignment and corrected for multiple hypotheses when assessing the association of the latent classes with demographic and neuropathological variables.ResultsWe identified five latent classes differentiated by level of impairment (high to low) and rate of decline (slow to fast). Within each latent class, the pattern of decline did not differ substantially across cognitive domains. Classes were associated with Show less

"SuperAgers" are oldest-old adults (ages 80+) whose memory performance more closely resembles middle-aged adults. The present study examined apolipoprotein E (APOE) allele frequency in non-Hispanic Black (NHB) and non-Hispanic White (NHW) SuperAgers compared to controls and Alzheimer's disease dementia cases. In 18,080 participants from eight cohorts, harmonized clinical diagnostics and memory, executive function, and language domain scores were used to identify SuperAgers, cases, and controls across age-defined bins. NHW SuperAgers had significantly lower frequency of APOE-ε4 alleles and higher frequency of APOE-ε2 alleles compared to all cases and controls, including oldest-old controls. Similar patterns were found in a small yet substantial sample of NHB SuperAgers; however, not all comparisons with controls reached significance. We demonstrated strong evidence that APOE allele frequency relates to SuperAger status. Further research is needed with a larger sample of NHB SuperAgers to determine if mechanisms conferring cognitive resilience differ across race groups. Apolipoprotein E (APOE) allele frequency differs between SuperAgers and cases APOE allele frequency differs between non-Hispanic White SuperAgers and controls The relationship of APOE and non-Hispanic Black SuperAger status is unclear. Show less

People with mild cognitive impairment (MCI) are candidates for early intervention, but not all progress to Alzheimer's disease (AD) dementia. Identifying a subgroup at highest risk may improve treatment targeting. We analyzed data from participants with MCI enrolled in the Alzheimer's Disease Neuroimaging Initiative (ADNI). Cognitive domains included memory, executive functioning, language, and visuospatial abilities. We evaluated baseline performance and 6-month change scores, using proportional hazards models to estimate associations with time to conversion to AD dementia. The strength of association varied by domain, but in general both baseline performance and 6-month change were associated with conversion. The strongest effects observed for memory and language. Observed associations were largely independent of established risk biomarkers, including APOE genotype, structural MRI measures, and CSF biomarkers. 6-month change scores on cognitive tests may help identify a high-risk subgroup of persons with MCI likely to progress to AD dementia. Systematic review. The authors reviewed the literature using traditional (e.g. PubMed) sources. There is a modest literature on change scores in the context of the AD clinical spectrum, but few investigations have evaluated whether short-term changes may be able to identify a high-risk subgroup of people with MCI. The authors have published a systematic review of this literature (Jutten et al. 2020) and appropriately refer to relevant citations here.Interpretation: Our findings suggest that short-term changes in cognition may be useful as part of a strategy to identify subsets of people with MCI who are at highest risk of conversion. Findings were clearest for memory and language. Domain-specific changes appeared to be independent from other biomarkers used to identify people at highest risk. Domain-specific changes did not appear to be better than changes in global cognition as measured by the MMSE or the CDR-sum of boxes.Future directions: Short-term changes in cognition may be useful to help identify a subgroup of people with MCI at highest risk of conversion to AD dementia. Future work could consider time frames shorter than the 6-month data we had available, better characterizing changes with more than 2 time points, or developing strategies that combine changes in cognition with other biomarkers to identify a subgroup of people with MCI to target for treatment. Show less