Sleep is a marker of brain function that could potentially identify patients for early intervention by detecting cognitive change during the early asymptomatic stages of Alzheimer disease (AD). We exa Show more
Sleep is a marker of brain function that could potentially identify patients for early intervention by detecting cognitive change during the early asymptomatic stages of Alzheimer disease (AD). We examined the relationship between sleep and cognition in cognitively unimpaired older adults and evaluated whether the relationship was altered by AD risk factors. Cognitively unimpaired older adults (N = 319, age 54-97 years) were administered a sleep diary (1x/day) and brief cognitive assessments (4x/day) for seven consecutive days via a smartphone application. We evaluated if a previous night's sleep predicts next-day cognition and if sleep averaged over a week predicts cognitive performance averaged over a week. Additional analyses included the effects of carrying an apolipoprotein (APOE) ε4 allele and cerebrospinal fluid biomarkers of AD pathology. At the between-person level, no associations were observed between sleep and cognition. Within-person analyses revealed that deviations (both higher and lower scores) from an individual's usual sleep pattern were associated poorer next day cognitive performance. Carriage of the APOE ε4 allele and AD biomarkers did not interact with sleep-cognition relationships. Remote, multi-day assessments of cognition and sleep revealed subtle non-linear associations between nightly sleep and next-day cognition in cognitively unimpaired older adults. Furthermore, the individualized nature of sleep-cognition relationships underscores the importance of maintaining consistent person-centered sleep health metrics to support cognitive function. Capturing latent AD-related changes in sleep and cognition among asymptomatic older adults may require repeated assessments across extended timeframes. Show less
Coronary heart disease (CHD) is the leading cause of mortality in African Americans. To identify common genetic polymorphisms associated with CHD and its risk factors (LDL- and HDL-cholesterol (LDL-C Show more
Coronary heart disease (CHD) is the leading cause of mortality in African Americans. To identify common genetic polymorphisms associated with CHD and its risk factors (LDL- and HDL-cholesterol (LDL-C and HDL-C), hypertension, smoking, and type-2 diabetes) in individuals of African ancestry, we performed a genome-wide association study (GWAS) in 8,090 African Americans from five population-based cohorts. We replicated 17 loci previously associated with CHD or its risk factors in Caucasians. For five of these regions (CHD: CDKN2A/CDKN2B; HDL-C: FADS1-3, PLTP, LPL, and ABCA1), we could leverage the distinct linkage disequilibrium (LD) patterns in African Americans to identify DNA polymorphisms more strongly associated with the phenotypes than the previously reported index SNPs found in Caucasian populations. We also developed a new approach for association testing in admixed populations that uses allelic and local ancestry variation. Using this method, we discovered several loci that would have been missed using the basic allelic and global ancestry information only. Our conclusions suggest that no major loci uniquely explain the high prevalence of CHD in African Americans. Our project has developed resources and methods that address both admixture- and SNP-association to maximize power for genetic discovery in even larger African-American consortia. Show less