OBJECTIVE—It has been argued that the relationship between depression and diabetes is bi-directional, but this hypothesis has not been explicitly tested. This systematic review examines the bi-directional prospective relationships between depression and type 2 diabetes. RESEARCH DESIGN AND METHODS—A search was conducted using Medline for publications from 1950 through 2007. Reviewers assessed the eligibility of each report by exposure/outcome measurement and study design. Only comparative prospective studies of depression and type 2 diabetes that excluded prevalent cases of depression (for diabetes predicting depression) or diabetes (for depression predicting diabetes) were included. Two sets of pooled risk estimates were calculated using random effects: depression predicting type 2 diabetes and type 2 diabetes predicting depression. RESULTS—Of 42 full-text publications reviewed, 13 met eligibility for depression predicting onset of diabetes, representing 6,916 incident cases. Seven met criteria for diabetes predicting onset of depression, representing 6,414 incident cases. The pooled relative risk (RR) for incident depression associated with baseline diabetes was 1.15 (95% CI 1.02–1.30). The RR for incident diabetes associated with baseline depression was 1.60 (1.37–1.88). CONCLUSIONS—Depression is associated with a 60% increased risk of type 2 diabetes. Type 2 diabetes is associated with only modest increased risk of depression. Future research should focus on identifying mechanisms linking these conditions.

Crucial advances have been made in our knowledge of the social determinants of health and health behaviors. Existing research on health disparities, however, generally fails to address a known paradox in the literature: While blacks have higher risk of medical morbidity relative to non-Hispanic whites, blacks have lower rates of common stress-related forms of psychopathology such as major depression and anxiety disorders. In this article we propose a new theoretical approach, the Environmental Affordances Model, as an integrative framework for the origins of both physical and mental health disparities. We highlight early empirical support and a growing body of experimental animal and human research on self-regulatory health behaviors and stress coping that is consistent with the proposed framework. We conclude that transdisciplinary approaches, such as the Environmental Affordances Model, are needed to understand the origins of group-based disparities to implement effective solutions to racial and ethnic group inequalities in physical and mental health.

Objectives. The objective of this study was to evaluate the impact of driving cessation on social integration and perceived support from relatives and friends among older adults. Methods. Data came from the population-based Baltimore Epidemiologic Catchment Area Study. We restricted analyses to participants aged 60+ with a history of driving (n = 398). Social integration (number and frequency of contact) and perceived social support from relatives/friends, driving status (continuing or ceased), and demographic and health characteristics were assessed at interviews 13 years apart. The potential mediating role of ability to use public transit was also investigated. We used repeated measures random-intercept models to evaluate the effect of driving cessation on social network characteristics over time. Results. Former drivers were older, were more likely to be female and non-White, had lower education, had poorer self-rated health, and had lower Mini-Mental State Examination scores relative to continuing drivers. Over the follow-up period, cessation was associated with reduced network of friends (odds ratio = 0.49, p <.05). This association was not mediated by ability to use public transportation. Cessation had no impact on support from friends or relatives. Discussion. Social integration is negatively affected by driving cessation even among elders who feel competent in using alternative forms of transportation, at least concerning networks of friends.

Prevalence of depression is associated inversely with some indicators of socioeconomic position, and the stress of social disadvantage is hypothesized to mediate this relation. Relative to whites, blacks have a higher burden of most physical health conditions but, unexpectedly, a lower burden of depression. This study evaluated an etiologic model that integrates mental and physical health to account for this counterintuitive patterning. The Baltimore Epidemiologic Catchment Area Study (Maryland, 1993–2004) was used to evaluate the interaction between stress and poor health behaviors (smoking, alcohol use, poor diet, and obesity) and risk of depression 12 years later for 341 blacks and 601 whites. At baseline, blacks engaged in more poor health behaviors and had a lower prevalence of depression compared with whites (5.9% vs. 9.2%). The interaction between health behaviors and stress was nonsignificant for whites (odds ratio (OR = 1.04, 95% confidence interval: 0.98, 1.11); for blacks, the interaction term was significant and negative (β: −0.18, P < 0.014). For blacks, the association between median stress and depression was stronger for those who engaged in zero (OR = 1.34) relative to 1 (OR = 1.12) and ≥2 (OR = 0.94) poor health behaviors. Findings are consistent with the proposed model of mental and physical health disparities.

We appreciate the thoughtful comments of Nouwen, Lloyd, and Pouwer (1) on our recent systematic review of the bidirectional relationship between depression and type 2 diabetes (2). They criticize the choice of only including studies that excluded cases of depression at baseline from the analysis of type 2 diabetes as a risk factor for incident depression because depression is a chronic condition and the absence of baseline depression does not rule out prior episodes. We agree with the instinct to measure the lifetime history of …