Body mass index and mental health problems in general adults: Disparity in gender and socioeconomic status

Objective: This nationwide population-based study aims to evaluate the association between Body Mass Index (BMI) and mental health problems, and to investigate the effects of gender and socioeconomic status (SES) on this association. Methods: This study was a longitudinal study. 12,862 adults (aged 18. years or older), who responded to the 2001 National Health Interview Survey (NHIS) and gave consent to the linking of the survey data to their National Health Insurance (NHI) claims records, were included. The 2002-2004 NHI claims records of the sample were analyzed. Logistic regression was used to evaluate the odds ratios. Those with middle and high income (per capita annual household income ≥. US$9375) in the sample were referred to as the better-offs. Results: After adjustment, increased BMI was significantly associated with a higher risk of schizophrenia (OR: 1.14, 95% CI: 1.07-1.22) and a lower risk of mood disorder (OR: 0.95, 95% CI: 0.91-0.99) in women. In addition, a higher BMI was significantly associated with a lower risk of mood disorders (risk reduction: 6%) and a lower risk of any major mental health problem (risk reduction: 3%) among the better-offs. Conclusions: In contrast to other (cross-sectional) studies in other countries, our longitudinal results suggest that in a general Taiwanese population, the association between BMI and mental health may vary by type of mental health problems. Gender and SES may have influenced this relationship. Further studies are required to elucidate the biological or social factors underlying these empirical observations.