Depression in diabetes and obesity

Abstract

Objectives: This study focuses on the comorbidity between depression and diabetes, as well as depression and obesity, in a biracial community sample of older adults. Methods: The data are drawn from a cross-sectional survey of five counties in North Carolina, USA, part of a longitudinal study of morbidity and mortality among elders in the urban and rural south. During the first wave of the survey, 4162 persons 65+ years of age participated in an interview at their homes. During this interview, data were collected to assess demographics, functional status, cognitive status, depression and self-report of diabetes. In addition, subjects were asked to estimate their height and weight for the interviewers, from which data body mass index (BMI) was estimated. Results: In both uncontrolled and controlled analyses, female gender, lower education, functional impairment and cognitive impairment were associated with comorbid depression/diabetes and depression/high BMI. Age was not associated with comorbid depression/diabetes but younger age was associated with depression/cognitive impairment. African American race was strongly associated with depression/diabetes but not with depression/high BMI. Conclusions: More studies of comorbidity in the general population should be implemented to determine the relationship between these comorbid conditions and risk factors. Longitudinal studies are especially needed.

Introduction

The association of depression, diabetes and obesity with race and gender is critical to the understanding of comorbid conditions in late life which may increase the risk of adverse health outcomes. Gavard et al. [1] reviewed 20 studies of the comorbidity of depression and diabetes and found that the prevalence of current depression in diabetic samples averaged around 15%, much higher than in the general population. Black et al. [2] found that 31.1% of older Mexican American diabetics reported clinically significant levels of depressive symptoms. These older diabetics with comorbid depression experienced a greater health burden than diabetics without depression and functioned at a lower level.

The increased frequency of diabetes among African Americans is well documented [3]. Diabetes is also more frequent in persons who are obese [4]. Siegel et al. [5] found that among African American women, overweight was associated with symptoms of depression, a relationship which is partially explained by health status (such as diabetes) but not by dietary restraint (dieting). The overweight/depression association was stronger among women with high levels of education and high levels of ethnic identity. In yet another study, the effect of body mass index (BMI) on diabetes risk was found to be different for black and white Americans, with a larger risk for blacks than whites at low BMI and an equivalent risk for both groups at high BMI [6].

In this study we explore the risk for comorbid depression/diabetes and depression/higher BMI by race, gender and a series of control variables in a community based sample of older adults. Though there is significant comorbidity between diabetes and depression, the comorbid conditions may not share the same risk factors/correlates. For example, young age and female gender are not risk factors for diabetes but are for depression [7]. African American race is a risk factor for diabetes but not for depression [8]. As there is some comorbidity between obesity and depression, some risk factors/correlates may be shared, such as female gender and a sedentary life style. On the other hand there is no clear racial/ethnic shared risk factor.