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 randomisation study
AID  - 10.1136/jech-2017-210000
DP  - 2018 Aug 01
TA  - Journal of Epidemiology and Community Health
PG  - 708--710
VI  - 72
IP  - 8
4099  - http://jech.bmj.com/content/72/8/708.short
4100  - http://jech.bmj.com/content/72/8/708.full
SO  - J Epidemiol Community Health2018 Aug 01; 72
AB  - Background Body mass index (BMI) is correlated negatively with subjective well-being and positively with depressive symptoms. Whether these associations reflect causal effects is unclear.Methods We examined bidirectional, causal effects between BMI and mental health with Mendelian randomisation using summary-level data from published genome-wide association studies (BMI: n=339 224; subjective well-being: n=204 966; depressive symptoms: n=161 460). Genetic variants robustly related to the exposure variable acted as instrumental variable to estimate causal effects. We combined estimates of individual genetic variants with inverse-variance weighted meta-analysis, weighted median regression and MR-Egger regression.Results There was evidence for a causal, increasing effect of BMI on depressive symptoms and suggestive evidence for a decreasing effect of BMI on subjective well-being. We found no evidence for causality in the other direction.Conclusion This study provides support for a higher BMI causing poorer mental health. Further research should corroborate these findings and explore mechanisms underlying this potential causality.