Major depressive disorder (MDD) and obesity are associated within individuals, but little is known about the association between MDD and obesity within families. We hypothesized that parental MDD would predict increased risk for adolescent obesity and that parental obesity would predict increased risk for adolescent MDD.Methods
Participants were drawn from the community-based Minnesota Twin Family Study (N = 7307; 17 years old: n = 3774). Parents and their 17-year-old offspring were assessed for MDD using a structured diagnostic interview, and direct assessments of height and weight were conducted (and diagnoses of obesity were derived from these measurements).Results
Parental MDD was associated with offspring obesity (odds ratio [OR] = 1.74, 95% confidence interval [CI] = 1.24–2.46). ORs representing the risk associated with maternal and paternal MDD were similar (OR = 1.42, 95% CI = 1.02–1.92; OR = 1.40, 95% CI = 0.88–2.20, respectively). This parental effect remained significant when adjusting for parental obesity and offspring MDD (OR = 1.67, 95% CI = 1.18–2.37). Maternal obesity was associated with increased risk for MDD in offspring (OR = 1.32, 95% CI = 1.06–1.64), but paternal obesity was associated with decreased risk for MDD among offspring (OR = 0.70, 95% CI = 0.54–0.91). These effects remained significant when adjusting for parental MDD and offspring obesity (OR = 1.36, 95% CI = 1.07–1.73; OR = 0.65, CI = 0.49–0.87, respectively). There were no differences in these findings by offspring sex (p values for all tests of a sex interaction term > .374).Conclusions
We found general support for hypothesized cross-disorder associations between MDD and obesity in parents and offspring, suggesting that a shared etiology may underlie these associations. Contrary to prediction, paternal obesity was associated with decreased risk for offspring MDD, a finding that requires further investigation.