Obesity and the three-year longitudinal course of bipolar disorder

Objectives: Despite substantial cross-sectional evidence that obesity is associated with an increased medical and psychiatric burden in bipolar disorder (BD), few longitudinal studies have examined this topic.

Methods: Subjects with BD (n = 1600) who completed both Wave 1 and Wave 2 of the National Epidemiologic Survey on Alcohol and Related Conditions were included. Analyses examined the association between obesity at Wave 1, and the subsequent course of BD, and of psychiatric and medical comorbidities, between Wave 1 and Wave 2.

Results: BD subjects with obesity (n = 506; 29.43%), compared to BD subjects without obesity (n = 1094; 70.57%) were significantly more likely to have a major depressive episode and to receive counseling for depression during follow-up, more likely to report a lifetime suicide attempt, and less likely to develop new-onset alcohol use disorders. These differences were no longer significant, however, after controlling for baseline demographic variables. No significant differences in new episodes or treatment of mania/hypomania were observed. After controlling for demographic variables, obese subjects remained significantly more likely to report any new-onset medical condition [odds ratio (OR) = 2.32, 95% confidence interval (CI): 1.63-3.30], new-onset hypertension (OR = 1.81, 95% CI: 1.16-2.82) and arthritis (OR = 1.64, 95% CI: 1.07-2.52). Obese subjects were significantly more likely to report physician-diagnosed diabetes (OR = 6.98, 95% CI: 4.27-11.40) and hyperlipidemia (OR = 2.32, 95% CI: 1.63-3.30) (assessed in Wave 2 only). The incidence of heart attacks was doubled among obese subjects, although this difference was not statistically significant.

Conclusions: The association between obesity and increased prospective depressive burden appears to be explained by baseline demographic variables. By contrast, obesity independently predicts the accumulation of medical conditions among adults with BD. Treatment of obesity could potentially mitigate the psychiatric and medical burden of BD.