BACKGROUND: Little evidence is available on the effects of incident diabetes or diabetes duration on cognitive aging. METHODS: We evaluated the effects of prevalent and incident diabetes on deteriorations in cognitive function, based on participants (n = 8,671) aged 65+ in the Health and Retirement Study in 2000. Inverse probability weighting was used to account for selective attrition and time-varying confounding of incident diabetes. RESULTS: Prevalent diabetes predicted higher odds of dementia [odds ratio 1.27; 95% confidence interval (CI) 1.03-1.58] and worse memory (-0.06 in z-score units; 95% CI -0.10 to -0.02), but incident diabetes or diabetes duration up to 8 years of follow-up was not predictive. CONCLUSION: Prevalent diabetes predicted lower cognition but not recent onset diabetes.

Population health improvements are the most relevant yardstick against which to evaluate the success of social epidemiology. In coming years, social epidemiology must increasingly emphasize research that facilitates translation into health improvements, with continued focus on macro-level social determinants of health. Given the evidence that the effects of social interventions often differ across population subgroups, systematic and transparent exploration of the heterogeneity of health determinants across populations will help inform effective interventions. This research should consider both biological and social risk factors and effect modifiers. We also recommend that social epidemiologists take advantage of recent revolutionary improvements in data availability and computing power to examine new hypotheses and expand our repertoire of study designs. Better data and computing power should facilitate underused analytic approaches, such as instrumental variables, simulation studies and models of complex systems, and sensitivity analyses of model biases. Many data-driven machine-learning approaches are also now computationally feasible and likely to improve both prediction models and causal inference in social epidemiology. Finally, we emphasize the importance of specifying exposures corresponding with realistic interventions and policy options. Effect estimates for directly modifiable, clearly defined health determinants are most relevant for building translational social epidemiology to reduce disparities and improve population health.

Research evidence indicates that 2 forms of racial discrimination - perceived interpersonal discrimination and racial/ethnic residential segregation (a form of institutional discrimination) - may influence children's health and disparities. Although research on these 2 forms of discrimination and health has primarily focused on adults, smaller bodies of work have documented that perceived interpersonal discrimination and segregation have a negative effect on infants' health, and that perceived interpersonal discrimination may negatively affect children's mental health. Three directions for research are (1) incorporating a life-course perspective into studies of discrimination and children's health, (2) linking residential segregation with geographyof- opportunity conceptual frameworks and measures, and (3) considering residential segregation along with segregation in other contexts that influence children's health (e.g., schools).

Research on racial residential segregation and health typically uses multilevel, population-based, slice-in-time data. Although research using this approach, including that by Kershaw et al. (Am J Epidemiol. 2013;177(4):299-309), has been valuable, I argue that to advance our understanding of how residential segregation influences health and health disparities, it is critical to incorporate a life-course perspective and integrate social theory. Applying a life-course perspective would entail modeling transitions, cumulative risk, and developmental and dynamic processes and mechanisms, as well as recognizing the contingency of contextual effects on different social groups. I discuss the need for analytic methods appropriate for modeling health effects of distal causes experienced across the life course, such as segregation, that operate through multiple levels and sequences of mediators, potentially across decades. Sociological theories of neighborhood attainment (e.g., segmented assimilation, ethnic resurgence, and place stratification theories) can guide effect-modification tests to help illuminate health effects resulting from intersections of residential processes, race/ethnicity, immigration, and other social determinants of health. For example, nativity and immigration history may crucially shape residential processes and exposures, but these have received limited attention in prior segregation-health literature.

Retaining severely impaired individuals poses a major challenge in longitudinal studies of determinants of dementia or memory decline. In the Health and Retirement Study (HRS), participants complete direct memory assessments biennially until they are too impaired to complete the interview. Thereafter, proxy informants, typically spouses, assess the subject's memory and cognitive function using standardized instruments. Because there is no common scale for direct memory assessments and proxy assessments, proxy reports are often excluded from longitudinal analyses. The Aging, Demographics, and Memory Study (ADAMS) implemented full neuropsychological examinations on a subsample (n=856) of HRS participants, including respondents with direct or proxy cognitive assessments in the prior HRS core interview. Using data from the ADAMS, we developed an approach to estimating a dementia probability and a composite memory score on the basis of either proxy or direct assessments in HRS core interviews. The prediction model achieved a c-statistic of 94.3% for DSM diagnosed dementia in the ADAMS sample. We applied these scoring rules to HRS core sample respondents born 1923 or earlier (n=5483) for biennial assessments from 1995 to 2008. Compared with estimates excluding proxy respondents in the full cohort, incorporating information from proxy respondents increased estimated prevalence of dementia by 12 percentage points in 2008 (average age=89) and suggested accelerated rates of memory decline over time.