Common mental disorder and obesity ― Insight from 4 repeat measures over 19 years: The prospective Whitehall II cohort study

Objective: To examine potential reciprocal associations between common mental disorders and obesity, and to assess whether there are dose-response relationships. Design: Prospective cohort study with four measures of common mental disorders and obesity over 19 years (Whitehall II study). Settings: Civil service departments in London. Participants: 4363 adults (28% female, mean age 44 years at baseline). Main outcome: Common mental disorder defined as General Health Questionnaire ‘caseness’; overweight and obesity based on Word Health Organization definitions. Results: In models adjusted for age, sex and body mass index at baseline, odds ratios for obesity at the fourth screening were 1.33 (95% confidence interval 1.00 to 1.77), 1.64 (1.13 to 2.36) and 2.01 (1.21 to 3.34) for participants with common mental disorder at one, two or three preceding screenings compared to individuals free from common mental disorder (ptrend<0.0001). The corresponding mean differences in body mass index at the last screening were 0.20, 0.31, 0.50 kg/m, respectively (ptrend<0.0001). These associations remained after adjustments for baseline characteristics related to mental health and the exclusion of participants who were obese at baseline. In addition, obesity predicted future risk of common mental disorder, again with evidence of a dose-response relationship (ptrend=0.02, multivariable model). However, this association was lost when individuals with common mental disorder at baseline were excluded (ptrend=0.33). Conclusions: These findings suggest that in British adults the direction of association between common mental disorders and obesity is from common mental disorder to increased future risk of obesity. This association is cumulative such that individuals with chronic or repeat episodes of common mental disorder are particularly at risk of weight gain. in se rm -0 04 26 80 7, v er si on 1 28 O ct 2 00 9