Body mass index and risk of mental disorders in the general population: Results from the Singapore Mental Health Study

Objective: The aims of the current study were to elucidate the association between Body Mass Index (BMI) and mental disorders and to examine whether these associations are moderated by socio-demographic correlates and comorbid physical disorders. Methods: The Singapore Mental Health Study (SMHS) surveyed adult Singapore Residents (Singapore Citizens and Permanent Residents) aged 18. years and above. The survey was conducted from December 2009 to December 2010. The diagnoses of mental disorders were established using the World Mental Health Composite International Diagnostic Interview version 3.0 (CIDI 3.0). BMI was calculated using height and weight which were self-reported by respondents. The Euro-Qol-5Dimensions (EQ-5D) was used to measure the health related quality of life (HRQoL) in the sample. Results: Six thousand and six hundred sixteen respondents completed the study (response rate of 75.9%) and constituted a representative sample of the adult resident population in Singapore. Being underweight was associated with both lifetime (adjusted odds ratio (OR): 2.3) and 12-month obsessive-compulsive disorder (adjusted OR: 4.4). Obesity was associated with 12-month alcohol dependence (adjusted OR: 8.4). There were no significant differences in the EQ-5D indices or the EQ-VAS scores among the four BMI groups in the population. Conclusions: Our findings are somewhat unique and different from those reported in research from Western countries. There is a need for further cross-cultural research to explore and identify genetic, metabolic and cultural differences that underlie the interaction between obesity and mental illnesses.