Major depressive disorder (MDD) is cross-sectionally and longitudinally associated with risk of type 2 diabetes (T2DM), as well as with an increased risk of micro- and macrovascular complications, worse metabolic control, and all-cause mortality. There is less evidence about similar associations between minor depression (MinD), the focus of this application, and T2DM or its secondary complications. We hypothesize that MinD, based on Diagnostic and Statistical Manual-IV-Text Revised (DSM-IV-TR) criteria, among adults with T2DM is prevalent and is associated with poor metabolic control, as is seen in MDD, and that this association might be explained by behavioral and biological factors associated with these disorders (i.e., poor health behaviors, impaired problem solving ability, and subclinical hypercortisolism). To preliminarily examine this hypothesis, our study has the following specific aims: 1) To estimate the prevalence of MinD in a clinic-based sample of adults with T2DM and compare it to the prevalence of MDD. 2) To compare glycemic control, assessed by glycated hemoglobin (HbA1c), between diabetic individuals with MinD and diabetic individuals with a) MDD or b) no depression. Secondary outcome measures of metabolic control will include LDL-cholesterol, HDL-cholesterol, triglycerides, body-mass index, waist circumference, blood pressure, and presence of diabetic complications. Our secondary aim will be to examine behavioral and hormonal factors that might explain the association between MinD and glycemic control among individuals with T2DM. To accomplish these aims, we propose to screen a clinical sample of up to 750 adults (250/year) with T2DM for depressive symptoms using the Patient Health Questionnaire-2 (PHQ-2) to identify 100 individuals who screen positive for a depressive disorder. We will perform a structured diagnostic psychiatric interview on these 100 individuals, which will enable us to differentiate MinD from MDD and other milder depressive disorders using DSM-IV-TR criteria. We will also perform a structured diagnostic interview on a random sample of 50 controls who screen negative on the PHQ-2 to adjust our prevalence estimates for screening biases on the PHQ-2. We will assess behavioral factors (diabetes-related health behaviors and problem-solving ability) in all participants and will assess subclinical hypercortisolism, using a dexamethasone suppression test, in all 100 subjects who screen positive on the PHQ-2 and in 50 random controls who screen negative on the PHQ-2. This preliminary study will be one of the first to establish the crude prevalence of MinD as a distinct disorder in a clinic-based sample and using a structured diagnostic interview.
We will screen a clinical sample of up to 750 adults (250/year) with type 2 diabetes for depressive symptoms using a questionnaire to identify 100 individuals who screen positive for a depressive disorder. We will perform a structured diagnostic psychiatric interview on these 100 individuals plus a random sample of 50 individuals who screen negative, which will enable us to estimate the frequency (prevalence) of minor depression, a milder depressive disorder, and distinguish it from major depression. We will compare metabolic control of diabetes between those with minor depression and those with 1) major depression and 2) no depression and explore whether behavioral and hormonal factors might explain the association.