Association Between Obesity and Depression Among American Blacks: Role of Ethnicity and Gender

Aim This study tested the association between obesity and major depressive disorder (MDD) in a national representative sample of Black adults in the USA. The study also explored the above association in subsamples based on ethnicity and gender. Method Data came from the National Survey of American Life (NSAL), a household mental health survey of adult Black Americans. Participants consisted of 5,191 Black adults (3,570 African Americans and 1,621 Caribbean Blacks). Classes I to III of obesity were defined based on body mass index (BMI) of equal or larger than 30, 35, and 40 kg/m(2), respectively. Twelve/month MDD was determined using the World Mental Health Composite International Diagnostic Interview (CIDI), a fully structured diagnostic interview. For each ethnicitygender subgroup, we ran a separate logistic regression model. We tested gradient and threshold effects of BMI on MDD. Unadjusted and adjusted odds ratios (ORs) were reported. Result Direction of association between BMI and MDD was reversed among men and women. Among men, there was a positive association between BMI and MDD, while among women, the association was negative. The gradient effect of BMI level on MDD reached statistical significance only among African American men (OR=0.71, 95 % confidence interval (CI)=0.51/0.99). Among women, a significant interaction was found between the effects of BMI >= 40 and African American ethnicity on odds of developing MDD [ change in OR= 8.840, 95 % CI=1.315/59.418]. That interaction term suggests that the effect of BMI >= 40 on MDD is significantly smaller among African American women than Caribbean Black women. Conclusion The direction and magnitude of the association between BMI and MDD among Blacks depend on ethnicity and gender. Risk of comorbid depression among women with severe obesity among Black women is smaller among African Americans than Caribbean Blacks.