Section II: The Research: Article Summaries and Commentaries Hypothesis 1. Depression is a risk factor for the development of type 2 diabetes.

Foundation Article

Eaton WW, Armenian HA, Gallo J, Pratt L, Ford DE: Depression and risk for onset of type II diabetes: a prospective population-based study. Diabetes Care 19:1097–1102, 1996

Summary and Commentary

Early studies using diagnostic interviews to extract lifetime histories of depression in diabetic subjects indicated that first episodes of major depression typically preceded the diagnosis of type 2 diabetes. A 13-year follow-up of participants in the Epidemiologic Catchment Area (ECA) by Eaton et al. provided some of the first longitudinal evidence that depression might be a risk factor for the development of diabetes. The ECA, a landmark study in psychiatric epidemiology, documented the prevalence of major psychiatric disorders in the United States. Its primary findings were summarized in Psychiatric Disorders in America by Robins and Regier.7

A structured interview, the Diagnostic Interview Schedule (DIS), was developed for the ECA study. It enabled trained lay interviewers to assess the symptoms that were used to diagnose psychiatric disorders such as major depression according to the American Psychiatric Association's official criteria. The DIS determines whether the subject has ever met the criteria for each disorder and, if so, when the most recent episode occurred. The subjects in the analyses by Eaton et al. were classified according to whether they had ever had a major depressive episode before their ECA interview, regardless of whether they were depressed at the time of the interview.

Utilizing the lifetime diagnosis of depression as a predictor of diabetes made it especially important to take age at enrollment into account. Older subjects had had more time to develop depression, diabetes, or both compared to younger subjects. However, individuals who already had diabetes at enrollment in the ECA were excluded from the analysis. Thus, age at enrollment influenced both inclusion in the sample and the participants' likelihood of ever having been depressed. …

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