Objectives:
The relationships between obesity and bipolar spectrum disorders (BSD) are unclear. Thus, the aim of our study were to approximate the prevalence of soft bipolar features in patients seeking treatment for obesity.

Methods:
We performed a nested case-control study (cases: 90 patients with the mean BMI=38.1±7.0 [range: 30.1–62.5]; controls: 70 healthy volunteers with the mean BMI=21.6±2.1 [range: 18.5–24.9]). The participants were screened for the BSD symptoms with the Mood Disorder Questionnaire.

Results:
Patients with obesity were significantly more likely to score ≥7 pts. on the MDQ 25.6% vs. 8.6%; p=0.01). In comparison to non-obese individuals, the obese patients scored significantly higher in MDQ section I and on the MDQ items referring to the ‘irritability–racing thoughts’ dimension of hypomania. The multiple logistic regression analysis revealed that obesity had been significantly related to the odds of obtaining ≥7 pts. on the MDQ section 1 (odds ratio [OR] = 2.07; 95% confidence interval [CI]: 1.17–3.63), and marginally significantly related to experiencing periods of ‘ups’ and ‘downs’(OR = 1.67; 95% CI: 1.00–2.81).

Conclusions:
Our study adds to previous suggestions that obesity may be significantly related to the BSD. However, the clinical implications of this finding need to be determined in further studies, performed in accordance with the paradigm of evidence based medicine (EBM).