Body mass index and risk of mental disorders in the general population: Results from the Singapore Mental Health Study Mythily Subramaniam a, ⁎, Louisa Picco a , Vincent He a , Janhavi Ajit Vaingankar a , Edimansyah Abdin a , Swapna Verma b , Gurpreet Rekhi a , Mabel Yap c , Jimmy Lee a , Siow Ann Chong a a Research Division, Institute of Mental Health, Buangkok Green Medical Park, Singapore, Singapore b Department of Early Psychosis Intervention, Institute of Mental Health, Singapore c Ministry of Health, Singapore abstract article info Article history: Received 28 August 2012 Received in revised form 18 October 2012 Accepted 20 October 2012 Keywords: Body mass index Health related quality of life Obsessive compulsive disorders Alcohol dependence 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 cor- relates and comorbid physical disorders. Methods: The Singapore Mental Health Study (SMHS) surveyed adult Singapore Residents (Singapore Citi- zens 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 Com- posite 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 asso- ciated 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 signifi- cant 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 cul- tural differences that underlie the interaction between obesity and mental illnesses. © 2012 Elsevier Inc. All rights reserved. Introduction Obesity has become a worldwide problem with significant increases in global obesity rates over the past few decades. A recent study that an- alyzed data from over 199 countries found that between 1980 and 2008, the mean BMI worldwide increased by 0.4 kg/m 2 per decade for men and 0.5 kg/m 2 per decade for women. The age-standardized prevalence of obesity worldwide was 9.8% in men and 13.8% in women. The study estimated that 205 million men and 297 million women worldwide were obese in 2008 [1]. Obesity is a serious public health problem, as it significantly increases the risk of chronic diseases such as cardiovascular diseases, type-2 diabetes, coronary-heart diseases, osteo-arthritis and certain cancers [2–4]. Thus, at a societal level, obesity has substantial di- rect and indirect cost that puts a strain on healthcare and social resources. The relationship between obesity and mental illnesses has re- ceived considerable attention in the past decade and a systematic re- view that explored the association between obesity and depression found a moderate level of evidence from prospective cohort studies that obesity was associated with a future occurrence of depression outcomes (it should be noted that of the four prospective studies reviewed, three were from the same population). Data from cross-sectional studies from the United States supported an associa- tion between obesity and prevalence of depression outcomes espe- cially for women, but most cross-sectional studies from populations other than the United States failed to find such associations [5]. Vari- ous mechanisms have been proposed for the association between obesity and depression including the social undesirability of obesity and associated dieting [6], stigmatization and low self-esteem among obese people [7], life style factors such as lack of exercise which may be associated with depression [8], and the association of obesity with physical illnesses which may in turn result in depression. Journal of Psychosomatic Research 74 (2013) 135–141 ⁎ Corresponding author at: Research Division, Institute of Mental Health, Buangkok Green Medical Park, 10 Buangkok View, Singapore 539747, Singapore. Tel.: +65 6389 3633; fax: +65 6343 7962. E-mail address: Mythily@imh.com.sg (M. Subramaniam). 0022-3999/$ – see front matter © 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jpsychores.2012.10.009 Contents lists available at SciVerse ScienceDirect Journal of Psychosomatic Research