Body mass index and depressive symptoms in middle aged and older adults

Background: The relationship between weight problems and depression has been the focus of many studies; however, results from these studies vary. The purpose of this study is to describe the association between depression and BMI using data from a national sample of middle aged and older Koreans and to examine whether gender moderates the relationship between depression and weight. Methods: We used data from the Korean Longitudinal Study of Aging (KLoSA). Of the 7,920 respondents that participated in KLoSA in 2010, 7,672 adults aged between 50 and 102 years were included in the final analysis. The relationship between depression and obesity status was examined in both the full sample and in sub-samples stratified by gender. The observed U-shaped association between obesity status and CES-D score was tested by regressing CES-D score on linear and quadratic terms of BMI scores. Results: The distribution of CES-D scores by respondents' obesity status (i.e., underweight, normal weight, overweight, obese and severely obese) showed a U-shaped association. Specifically, the highest CES-D scores were found in underweight individuals; this was followed by the severely obese and obese groups in the full sample and in gender-specific subsamples. The lowest CES-D scores were found in the overweight group when considering the entire population and males alone and in the normal weight group for females. This U-shaped association between CES-D and obesity status was confirmed by a model in which CES-D scores were regressed on BMI scores and other covariates. Conclusions: This study found a U-shaped association between BMI and levels of depressive symptoms among adults in Korea overall and also within each gender. Specifically, the highest level of depressive symptoms was found among the underweight, followed by the severely obese and then the obese. Slightly different patterns between male and female adults were found regarding the weight status associated with the fewest depressive symptoms.