Obesity not linked to bipolar disorder course

By Mark Cowen, senior medwireNews Reporter

Obesity is not significantly associated with psychiatric disease course in patients with bipolar disorder (BD), Canadian researchers report.

In a 3-year study of 1600 patients with BD, the team found that obese patients (n=506), with a body mass index of 30kg/m² or higher, were more likely to experience a depressive episode (51.1 vs 44.4%), receive counseling/psychotherapy for depression (60.3 vs 50.1%), and report a lifetime suicide attempt (29.8 vs 20.9%) than non-obese subjects.

But these differences were attenuated and no longer significant after accounting for baseline variables, such as age, gender, employment status, exposure to childhood abuse, ethnicity, and marital status, note Benjamin Goldstein (University of Toronto, Ontario, Canada) and colleagues.

And no significant differences were observed between the groups in the incidence and treatment of manic/hypomanic episodes during follow up.

However, obesity remained significantly associated with the incidence of several new-onset medical conditions during follow up after controlling for baseline variables.

Indeed, compared with non-obese BD patients, obese patients were significantly more likely to develop hypertension (odds ratio [OR]=1.81) and arthritis (OR=1.64) during the study period.

The risk for physician-diagnosed diabetes (OR=6.98) and hyperlipidemia (OR=2.32) was also significantly increased among obese compared with non-obese patients.

The incidence of heart attacks was twice as high in obese as non-obese patients during follow up, at 2.34% versus 0.99%. But due to the relatively small number of such events, the study was not adequately powered to detect a significant difference between the groups.

Goldstein and colleagues conclude in Bipolar Disorders: "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."

They add: "Treatment of obesity could potentially mitigate the psychiatric and medical burden of BD. Increasing evidence suggests that integrating models of care focusing simultaneously on psychiatric and medical outcomes may optimize global outcomes in BD."

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