Genome-wide analysis of screen behaviors among adolescents identifies novel loci and overlap with educational attainment and mental disorders

Technological devices play a central role in adolescents' life. Despite concerns about negative effects of excessive screen time, there is little knowledge of screen behaviors' genetic architecture. Using self-reports from adolescents in the Norwegian Mother, Father, and Child Cohort Study (n = 18,490), we performed genome-wide association analysis for four screen behaviors: time spent (1) watching television; (2) gaming; (3) sitting/lying down with a screen device; and (4) using social media. The resulting summary statistics were analysed using the conditional false discovery rate (condFDR) approach to increase genetic discovery. We also estimated SNP-heritabilities of the screen behaviors and genetic correlations with eight psychiatric disorders (schizophrenia, bipolar disorder, major depressive disorder, autism spectrum disorder, attention-deficit hyperactivity disorder, anorexia nervosa, cannabis use disorder and alcohol use disorder), and educational attainment. Screen behaviors displayed significant SNP-heritabilities (0.048-0.12). We observed significant genetic correlations between screen behaviors and psychiatric disorders (r_g range: 0.21-0.42). Educational attainment demonstrated negative genetic correlation with screen behaviors, most strongly with social media use (r_g = - 0.69). CondFDR analysis identified three novel loci associated with social media use. Thus, we show that screen behaviors are heritable, polygenic traits that partly share genetic signal with mental disorders and educational attainment.