Genetic Overlap between Executive Functions and Body Mass Index in Childhood

Executive functions (EFs) are cognitive processes foundational to complex reasoning and goal-directed behavior. EFs share genetic variance between themselves and with general cognitive ability (IQ), and predict academic... [ view full abstract ]

Executive functions (EFs) are cognitive processes foundational to complex reasoning and goal-directed behavior. EFs share genetic variance between themselves and with general cognitive ability (IQ), and predict academic achievement. Obesity is also inversely associated with academic achievement and IQ, highlighting its importance to cognitive development. Recently, an inverse relation has emerged between body mass index (BMI) and EFs; however the underlying mechanisms are not well understood. The aim of the current study was to decompose the inverse EF-BMI association into genetic and environmental influences, and to gauge the specificity of any EF-BMI association in relation to general cognitive abilities and academic achievement. Twins ages 7-15-year-old participating in the Texas Twin Project (N=896) completed a neuropsychological test battery measuring core EFs (inhibition, working memory, switching and updating), academic achievement (in reading and mathematics), and general cognitive abilities (IQ, crystalized intelligence, fluid intelligence and processing speed), and had their heights and weights measured. Associations were run between BMI and cognitive variables, specifying EFs as individual domains and as a higher-order common factor thought to represent the capacity to control and regulate attention selectively. BMI was inversely associated with nearly all cognitive measures (FDR-corrected P-values [Qs] <.05). However after controlling for age, sex, and race/ethnicity, only updating (r=-.321; Q=.04) and the latent EF factor (r= -.125; P =.01;Q =.04) remained significant. The inverse association between BMI and the latent EF factor was due to a significant genetic correlation accounting for 80% of the phenotypic association (r_G =-.15; P < .001). These findings confirm that the ability to self-regulate attention is reduced as BMI increases, and reveal this is primarily attributable to shared genetic influences between EF and BMI. This adds to a growing body of research suggesting there are a set of genetic variants important to both physical health and cognitive functioning.