Overweight and obesity in patients with bipolar disorder or schizophrenia compared with a non-psychiatric sample

Objective

Multiple studies suggest an association of overweight and obesity with bipolar disorder (BD) and schizophrenia. The goal of this paper was to determine the magnitude of this association and its relationship with previous course-of-illness and other variables of clinical interest.

Methods

The prevalence of overweight and obesity was compared among patients with BD (n = 108), patients with schizophrenia (n = 250) and a non-psychiatric control group (n = 290). Moreover, within each group we analyzed the variables associated with overweight including obesity, i.e., body mass index (BMI) ≥ 25] and obesity (BMI ≥ 30) adjusting for a possible confounding effect of sex, age and educational level by logistic regression.

Results

In comparison with the non-psychiatric sample, a strong association of both BMI ≥ 25 and obesity was observed with BD and schizophrenia (adjusted odds ratios between 3.4 and 4.6; P-values < 0.001). Overweight was significantly associated with male sex and increasing age in both control and BD groups; and with female sex among schizophrenia patients. Moreover, for BD patients, earlier onset of first BD symptoms, presence of a non-psychiatric illness, current use of mood-stabilizing medication, and being a non-smoker were significantly associated with overweight; and male sex and the presence of a non-psychiatric illness, with obesity. Within the schizophrenia patients, obesity was significantly associated with female sex, intermediate age range and lower PANSS score.

Conclusions

Among patients with BD or schizophrenia, the chronic course of their illness and their current treatment with psychotropic medication might be more relevant for becoming overweight or obese than the specific psychiatric illness.