Relationship of obesity to depression: a family-based study

Objective: To examine the relationship between obesity and depression in a sample of extremely obese individuals and their siblings and parents. Subjects: A total of 1730 European Americans (558 men, 1172 women, aged 49.29+/-15.42 y, body mass index (BMI) of 35.57+/-11.53 kg/m(2)) and 373 African Americans (103 men, 270 women, aged 44.85+/-15.08 years, BMI of 36.83+/-11.31 kg/m(2)) in a sample of 482 nuclear families segregating extreme obesity and normal weight. Measurements: Individual BMI, history of depression treatment and covariates (age, sex, race, education, marital status, socioeconomic status, chronic medical conditions and exercise program). Results: Greater odds for depression were found for the obese, European American, women, the unmarried, the more educated, those with chronic physical disorder(s) and the offspring of depressed parents. A trend test found that the odds ratios for depression increased with BMI and number of chronic medical conditions (P<0.0001). Multivariate logistic regression analyses indicated that BMI, race, marital status, chronic medical conditions and family history were the predicators of depression for both the genders. Hierarchical analyses revealed that BMI significantly increased the risk above that predicated by the combined effects of all other variables. Conclusions: Extreme obesity was associated with the increased risk for depression across gender and racial groups, even after controlling for chronic physical disease, familial depression and demographic risk factors. More detailed research is needed to determine the underlying mechanisms.