The obese brain as a heritable phenotype-A combined morphometry and twin study

Background: Body weight and adiposity are heritable traits. To date, it remains unknown whether obesity-associated brain structural alterations are under a similar level of genetic control. Methods: For this study, we utilized magnetic resonance imaging data from the Human Connectome Project. Voxel-based morphometry was used to investigate associations between body mass index (BMI) and regional gray matter volume (GMV) in a sample of 875 young adults with a wide BMI range (386 males/489 females; age 28.8±3.7 years; BMI 26.6±5.3 kg m−2) that included 86 pairs of monozygotic twins and 82 pairs of dizygotic twins. Twin data were analyzed by applying the additive genetic, common environmental and residual effects model to determine heritability of brain regions that were associated with BMI. Results: We observed positive associations between BMI and GMV in the ventromedial prefrontal cortex and the right cerebellum and widespread negative associations within the prefrontal cortex, cerebellum, temporal lobes and distinct subcortical structures. Varying degrees of heritability were found for BMI-associated brain regions, with the highest heritability estimates for cerebellar GMV and subcortical structures. Conclusions: These data indicate that brain regions associated with obesity are subject to differing levels of genetic control and environmental influences. Specific brain regions with high heritability might represent an inherent vulnerability factor for obesity.