Brain structural differences in monozygotic twins discordant for body mass index

Background:Substantial efforts have been made to investigate the neurobiological underpinnings of human obesity with a number of studies indicating a profoundinfluence of increased body weight on brain structure. Although body weight is known to be highly heritable, uncertainty remains regarding the respective contri-bution of genetic and environmental influences.Methods:In this study we used structural magnetic resonance imaging (MRI) data from the Human Connectome Project (HCP). Voxel-based morphometry (VBM) wasapplied to study BMI-associated differences in gray matter volume (GMV) within monozygotic (MZ) twin pairs discordant for BMI (ΔBMI>2.5 kg*m2,n¼68 pairs).In addition, we investigated the relationship ofΔBMI (entire range) with GMV differences within the entire sample of MZ twin pairs (n¼153 pairs).Results:Analyses of BMI discordant twin pairs yielded less GMV in heavier twin siblings (p