T25 - The VAL66MET Bdnf Genetic Polymorphism Does Not Modify The Association Between Major Depression And Body Mass Index (BMI)

Abstract

Listen

Translate article

Background Depression and obesity are highly prevalent diseases in the general population, responsible of disability burden worldwide. Recently, a bidirectional relationship between both disorders has been described but the biological explanation of this reciprocal link is still unknown. The association between the BDNF Val66Met polymorphism and depression has been described in several studies. Besides, this polymorphism has also been associated with eating behavior, eating disorders and body mass index (BMI). The aim of this study is to investigate the genetic influence of the BDNF Val66Met polymorphism in relation to BMI in a population-based sample of individuals with major depression versus controls. Methods We performed a case-control study including 337 individuals with major depression and 921 healthy controls from the Granad∑p and PISMA-ep studies from the region of Andalusia (Spain). The MINI was used to establish the diagnostic of depression. Height and weight data reported from each individual was used to calculate BMI using the formula: weight(kg)/height(m)2. T-tests were used to analyze the association between major depression and BMI. Linear regression models for quantitative traits assuming an additive genetic model were applied to analyze the association between the BDNF Val66Met polymorphism and BMI. First, the analyses were carried out in the whole sample, and then separately in cases and controls. The regression analyses were adjusted by sex, age, province and depression status in the whole sample. When cases and controls were analyzed separately, sex, age and province were included as covariates in the models. Finally, we performed interaction analysis between the Val66Met polymorphism, major depression and BMI. The statistical analyses were carried out with the software PLINK v1.06. Results We found a statistically significant association between major depression and BMI. The individuals with depression had significantly higher BMI values compared to controls (cases: BMI=27.54 (SD=5.75); controls: BMI=26.75 (SD=4.76); t=-2.34, P=0.009). No significant differences were found in the allelic or genotypic frequencies distribution when cases and controls were compared. Linear regression analyses did not show a significant association between the Val66Met polymorphism and BMI, neither in the whole sample (β=-0.1035, p=0.651) nor when cases and controls were analyzed separately (cases: β=-0.791, p=0.134; controls: β=-0.177, p=0.470). No interaction between the Val66Met polymorphism and major depression was found in relation to BMI (β=-0.787, P=0.14). Discussion Our results show an association between BMI and major depression confirming the results from previous studies. However, our study does not support the implication of the BDNF Val66Met polymorphism in the genetic relationship between BMI and major depression.