PT  - JOURNAL ARTICLE
AU  - Nina van den Broek
AU  - Jorien L. Treur
AU  - Junilla K. Larsen
AU  - Maaike Verhagen
AU  - Karin J. H. Verweij
AU  - Jacqueline M. Vink
TI  - Causal Associations Between Body Mass Index and Mental Health: A Mendelian Randomization Study
AID  - 10.1101/168690
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 168690
4099  - http://biorxiv.org/content/early/2017/07/26/168690.short
4100  - http://biorxiv.org/content/early/2017/07/26/168690.full
AB  - Background Body Mass Index (BMI) is negatively correlated with subjective well-being and positively correlated with depressive symptoms. Whether these associations reflect causal effects or confounding is unclear.Methods We examined causal effects between BMI and subjective well-being/depressive symptoms with bi-directional, two-sample Mendelian randomization using summary-level data from large genome-wide association studies. Genetic variants robustly related to the exposure variable acted as instrumental variable (two thresholds were used; p<5e-08 and p<1e-05). These ‘instruments’ were then associated with the outcome variable. Pleiotropy was corrected for by two sensitivity analyses.Results Substantial evidence was found for a causal effect of BMI on mental health, such that a higher BMI decreased subjective well-being and increased depressive symptoms. No consistent evidence was found for causality in the other direction.Conclusions This study provides support for a higher BMI causing poorer mental health. Further research should corroborate these findings and consider non-linear effects and sex differences.