Cognitively Stimulating Activities: Effects on Cognition across Four Studies with up to 21 Years of Longitudinal Data

Engagement in cognitively stimulating activities has been considered to maintain or strengthen cognitive skills, thereby minimizing age-related cognitive decline. While the idea that there may be a modifiable behavior that could lower risk for cognitive decline is appealing and potentially empowering for older adults, research findings have not consistently supported the beneficial effects of engaging in cognitively stimulating tasks. Using observational studies of naturalistic cognitive activities, we report a series of mixed effects models that include baseline and change in cognitive activity predicting cognitive outcomes over up to 21 years in four longitudinal studies of aging. Consistent evidence was found for cross-sectional relationships between level of cognitive activity and cognitive test performance. Baseline activity at an earlier age did not, however, predict rate of decline later in life, thus not supporting the concept that engaging in cognitive activity at an earlier point in time increases one's ability to mitigate future age-related cognitive decline. In contrast, change in activity was associated with relative change in cognitive performance. Results therefore suggest that change in cognitive activity from one's previous level has at least a transitory association with cognitive performance measured at the same point in time

Predictors of Retest Effects in a Longitudinal Study of Cognitive Aging in a Diverse Community-Based Sample

Better performance due to repeated testing can bias long-term trajectories of cognitive aging and correlates of change. We examined whether retest effects differ as a function of individual differences pertinent to cognitive aging: race/ethnicity, age, sex, language, years of education, literacy, and dementia risk factors including apolipoprotein E ε4 status, baseline cognitive performance, and cardiovascular risk. We used data from the Washington Heights-Inwood Columbia Aging Project, a community-based cohort of older adults (n=4073). We modeled cognitive change and retest effects in summary factors for general cognitive performance, memory, executive functioning, and language using multilevel models. Retest effects were parameterized in two ways, as improvement between the first and subsequent testings, and as the square root of the number of prior testings. We evaluated whether the retest effect differed by individual characteristics. The mean retest effect for general cognitive performance was 0.60 standard deviations (95% confidence interval [0.46, 0.74]), and was similar for memory, executive functioning, and language. Retest effects were greater for participants in the lowest quartile of cognitive performance (many of whom met criteria for dementia based on a study algorithm), consistent with regression to the mean. Retest did not differ by other characteristics. Retest effects are large in this community-based sample, but do not vary by demographic or dementia-related characteristics. Differential retest effects may not limit the generalizability of inferences across different groups in longitudinal research

The Role of Early-Life Educational Quality and Literacy in Explaining Racial Disparities in Cognition in Late Life

ObjectivesRacial disparities in late-life cognition persist even after accounting for educational attainment. We examined whether early-life educational quality and literacy in later life help explain these disparities.MethodWe used longitudinal data from the Washington Heights-Inwood Columbia Aging Project (WHICAP). Educational quality (percent white students; urban/rural school; combined grades in classroom) was operationalized using canonical correlation analysis. Late-life literacy (reading comprehension and ability, writing) was operationalized using confirmatory factor analysis. We examined whether these factors attenuated race-related differences in late-life cognition.ResultsThe sample consisted of 1,679 U.S.-born, non-Hispanic, community-living adults aged 65-102 (71% black, 29% white; 70% women). Accounting for educational quality and literacy reduced disparities by 29% for general cognitive functioning, 26% for memory, and 32% for executive functioning but did not predict differences in rate of cognitive change.DiscussionEarly-life educational quality and literacy in late life explain a substantial portion of race-related disparities in late-life cognitive function

Association of Vascular Risk Factors With Cognition in a Multiethnic Sample

ObjectivesTo examine the relationship between cardiovascular risk factors (CVRFs) and cognitive performance in a multiethnic sample of older adults.MethodWe used longitudinal data from the Washington Heights-Inwood Columbia Aging Project. A composite score including smoking, stroke, heart disease, diabetes, hypertension, and central obesity represented CVRFs. Multiple group parallel process multivariate random effects regression models were used to model cognitive functioning and examine the contribution of CVRFs to baseline performance and change in general cognitive processing, memory, and executive functioning.ResultsPresence of each CVRF was associated with a 0.1 SD lower score in general cognitive processing, memory, and executive functioning in black and Hispanic participants relative to whites. Baseline CVRFs were associated with poorer baseline cognitive performances among black women and Hispanic men. CVRF increase was related to baseline cognitive performance only among Hispanics. CVRFs were not related to cognitive decline. After adjustment for medications, CVRFs were not associated with cognition in Hispanic participants.DiscussionCVRFs are associated with poorer cognitive functioning, but not cognitive decline, among minority older adults. These relationships vary by gender and medication use. Consideration of unique racial, ethnic, and cultural factors is needed when examining relationships between CVRFs and cognition

Association between Cholesterol Exposure and Neuropathological Findings: The ACT Study

We characterized the relationship between late life cholesterol exposure and neuropathological outcomes in a community-based, older adult cohort. Adult Changes in Thought (ACT) is a cohort study that enrolls consenting, randomly selected, non-demented people aged ≥65 from a healthcare delivery system. We used late life HDL and total cholesterol lab values from Group Health computerized records, and calculated HDL and non-HDL levels. We evaluated neuropathological outcomes of Alzheimer's disease, cerebral amyloid angiopathy, vascular brain injury, and Lewy body disease. Using linear mixed models with age and antilipemic medication as predictors, we obtained predicted cholesterol values at age 70 and 10 years prior to death for individuals with available cholesterol data in 10-year exposure windows. We used logistic regression to determine whether predicted late life cholesterol levels were associated with neuropathological outcomes controlling for age at death, APOE genotype, sex, and their interactions with cholesterol levels. 525 decedents came to autopsy by 08/2014. Of these, plasma cholesterol concentration was available for 318 (age 70, model 1) and 396 (10 years prior to death, model 2) participants. We did not find associations between late life cholesterol and Alzheimer's disease neuropathological changes, and there were no associations between cholesterol levels and amyloid angiopathy or vascular brain injury. We observed an association between predicted non-HDL cholesterol at age 70 and Lewy body disease. Our study suggests an association between late life non-HDL cholesterol exposure and Lewy body disease. We did not observe associations between late life cholesterol levels and Braak stage or CERAD score