Depression and body mass index, differences by education: Evidence from a population-based study of adult women in the U.S. Buffalo-Niagara region

The relationship between obesity and depression is well described. However, the evidence linking depression and body mass index (BMI) across the broad range of body size is less consistent. We examined the association between depressive symptoms and BMI in a sample of adult women in the Buffalo-Niagara region between 1997 and 2001. Using logistic regression, we investigated whether increased weight status beyond normal-weight was associated with a higher prevalence of depressive symptoms, and if educational attainment modified the association between obesity and depression. There was a trend for increased weight status to be associated with higher depressive symptoms (obese II/III, OR 1.57, 95% CI 1.03-2.41), whereas higher education was associated with lower odds of depressive symptoms, in an adjusted model including BMI (more than 12 but less than 16 years, OR 0.70, 95% CI 0.49-0.98; 16 or more years of education, OR 0.61, 95% CI 0.40-0.93). The association of being obese I with depressive symptoms was different for more educated (OR 2.15, 95% CI 1.27-3.62) compared to less educated women (OR 0.90, 95% CI 0.50-1.62); the sample was larger for the more educated women and reached statistical significance. There were no differences in the association for obese II/III women in strata of education. There was evidence of risk-difference heterogeneity (0.88, 95% CI 0.84-0.93). In this population-based sample of women in western New York state, increased weight was negligibly associated with depressive symptoms. The association of being obese I with depressive symptoms was different for more compared to less educated women.