Epidemiology and Care of Comorbid Obesity and Depression

Obesity is a significant and growing public health concern, accounting for approximately 300,000 excess deaths per year and approximately 9% of US health care expenditures. Prevalence of obesity has steadily increased, with an estimated rate among middle-aged women exceeding 30%. Obesity has a substantial impact on medical morbidity and health-related quality of life.

Public health approaches to the prevention and treatment of obesity must consider the substantial overlap with depression. Some data suggest a 50% increase in risk of depression among obese women. Women with a history of depression or depression treatment are over-represented among those seeking obesity treatment. Current or past depression is also associated with less success in losing weight or maintaining weight loss. Because women with depressive disorders are typically excluded from clinical trials of weight loss treatments, data on the management of comorbid depression and obesity are limited.

We propose two related studies: A population-based epidemiologic study of the association between obesity and depression among women and a longitudinal study of obesity treatment among two cohorts (one with comorbid obesity and depression, one with obesity only) identified by the epidemiologic study.

Study 1 - Epidemiologic Study: A population-based sample of approximately 6000 women aged 40-65 will complete structured telephone assessment of weight, nutrient intake, physical activity, depression, functional impairment, and disability. Women with Body Mass Index (BMI) >30 will be oversampled. Insurance claims data will be used to measure health care costs. Aims of the epidemiologic study include:

• Examine the association between obesity and depression among middle-aged women. Secondary analyses will examine possible mechanisms for any association.
• Examine the specific contributions of obesity and depression to disability, functional impairment, and health care utilization and cost.

Study 2 - Treatment study: A cohort of approximately 100 women with obesity (BMI > 30) and no current depressive disorder will be enrolled in a 6-month state-of-the-art group weight loss treatment. Approximately 200 women with comorbid obesity and depression will be randomly assigned to either the identical weight loss treatment or to a combined cognitive-behavior group therapy program focused on both depression and weight loss. Aims of the treatment study will include:

• Examine the effect of depression on success in weight loss treatment by comparing weight loss, nutrient intake, and physical activity in depressed and non-depressed women enrolled in the identical weight loss program. Secondary analyses will examine mechanisms for any observed difference.
• Examine the benefits of a combined weight loss/depression intervention above those of weight loss treatment alone by comparing weight loss, nutrient intake, physical activity, depressive symptoms, functional impairment, and disability in the two groups of women with comorbid obesity and depression randomly assigned to the two different intervention programs.

Inclusion criteria

• Age 40 to 65
• Body Mass Index >= 30
• Clinically significant depression
• PHQ score of 10 or more
• Current or past major depressive episode
• Current symptoms include depressed mood or loss of interest
• Enrolled in Group Health Cooperative health plan

Exclusion criteria

• History of treatment for bipolar disorder or schizophrenia
• Not willing to participate in group intervention
• Medical contra-indications to graded exercise program
• Unable to walk for 10 minutes