6 research outputs found
Tutorial on directed acyclic graphs
Directed acyclic graphs (DAGs) are an intuitive yet rigorous tool to communicate about causal questions in clinical and epidemiologic research and inform study design and statistical analysis. DAGs are constructed to depict prior knowledge about biological and behavioral systems related to specific causal research questions. DAG components portray who receives treatment or experiences exposures; mechanisms by which treatments and exposures operate; and other factors that influence the outcome of interest or which persons are included in an analysis. Once assembled, DAGs - via a few simple rules - guide the researcher in identifying whether the causal effect of interest can be identified without bias and, if so, what must be done either in study design or data analysis to achieve this. Specifically, DAGs can identify variables that, if controlled for in the design or analysis phase, are sufficient to eliminate confounding and some forms of selection bias. DAGs also help recognize variables that, if controlled for, bias the analysis (e.g., mediators or factors influenced by both exposure and outcome). Finally, DAGs help researchers recognize insidious sources of bias introduced by selection of individuals into studies or failure to completely observe all individuals until study outcomes are reached. DAGs, however, are not infallible, largely owing to limitations in prior knowledge about the system in question. In such instances, several alternative DAGs are plausible, and researchers should assess whether results differ meaningfully across analyses guided by different DAGs and be forthright about uncertainty. DAGs are powerful tools to guide the conduct of clinical research
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Do the Benefits of Educational Attainment for Late-life Cognition Differ by Racial/Ethnic Group?
IntroductionEducational attainment is associated with late-life cognitive performance and dementia; few studies have examined diverse racial/ethnic groups to assess whether the association differs by race/ethnicity.MethodsWe investigated whether the association between educational attainment and cognition differed between White, Black, Asian, and Latino participants in the Kaiser Healthy Aging and Diverse Life Experiences study (n=1348). Covariate-adjusted multivariable linear regression models examined domains of verbal episodic memory, semantic memory, and executive functioning.ResultsWe observed significant effect heterogeneity by race/ethnicity only for verbal episodic memory (P=0.0198), for which any schooling between high school and college was beneficial for White, Asian, and Black participants, but not Latino participants. We found no evidence of heterogeneity for semantic memory or executive function.DiscussionWith the exception of Latino performance on verbal episodic memory, more education consistently predicted better cognitive scores to a similar extent across racial/ethnic groups, despite likely heterogenous educational and social experiences
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Postsecondary Education and Late-life Cognitive Outcomes Among Black and White Participants in the Project Talent Aging Study
BackgroundHigher education consistently predicts improved late-life cognition. Racial differences in educational attainment likely contribute to inequities in dementia risk. However, few studies of education and cognition have controlled for prospectively measured early-life confounders or evaluated whether the education late-life cognition association is modified by race/ethnicity.MethodsAmong 2343 Black and White Project Talent Aging Study participants who completed telephone cognitive assessments, we evaluated whether the association between years of education and cognition (verbal fluency, memory/recall, attention, and a composite cognitive measure) differed by race, and whether these differences persisted when adjusting for childhood factors, including the cognitive ability.ResultsIn fully adjusted linear regression models, each additional year of education was associated with higher composite cognitive scores for Black [β=0.137; 95% confidence interval (CI)=0.068, 0.206] and White respondents (β=0.056; CI=0.034, 0.078) with an interaction with race ( P =0.03). Associations between education and memory/recall among Black adults (β=0.036; CI=-0.037, 0.109) and attention among White adults (β=0.022; CI=-0.002, 0.046) were nonsignificant. However, there were significant race-education interactions for the composite ( P =0.03) and attention measures ( P <0.001) but not verbal fluency ( P =0.61) or memory/recall ( P =0.95).ConclusionEducation predicted better overall cognition for both Black and White adults, even with stringent control for prospectively measured early-life confounders
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Bachelors, divorcees, and widowers: Does marriage protect men from type 2 diabetes?
© 2014 Cornelis et al.While research has suggested that being married may confer a health advantage, few studies to date have investigated the role of marital status in the development of type 2 diabetes. We examined whether men who are not married have i
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Racial and ethnic differences in the association between depressive symptoms and cognitive outcomes in older adults: Findings from KHANDLE and STAR
IntroductionDepressive symptoms are associated with higher risk of dementia, but how they impact cognition in diverse populations is unclear.MethodsAsian, Black, Latino, or White participants (n = 2227) in the Kaiser Healthy Aging and Diverse Life Experiences (age 65+) and the Study of Healthy Aging in African Americans (age 50+) underwent up to three waves of cognitive assessments over 4 years. Multilevel models stratified by race/ethnicity were used to examine whether depressive symptoms were associated with cognition or cognitive decline and whether associations differed by race/ethnicity.ResultsHigher depressive symptoms were associated with lower baseline verbal episodic memory scores (-0.06, 95% CI: -0.12, -0.01; -0.15, 95% CI: -0.25, -0.04), and faster decline annually in semantic memory (-0.04, 95% CI: -0.07, -0.01; -0.10, 95% CI: -0.15, -0.05) for Black and Latino participants. Depressive symptoms were associated with lower baseline but not decline in executive function.DiscussionDepressive symptoms were associated with worse cognitive outcomes, with some evidence of heterogeneity across racial/ethnic groups.HighlightsWe examined whether baseline depressive symptoms were differentially associated with domain-specific cognition or cognitive decline by race/ethnicity. Depressive symptoms were associated with worse cognitive scores for all racial/ethnic groups across different domains examined. Higher depressive symptoms were associated with faster cognitive decline for semantic memory for Black and Latino participants. The results suggest a particularly harmful association between depressive symptoms and cognition in certain racial/ethnic groups