Gene-environment interaction in ADHD traits: the role of school environment, personality, callousness-unemotional traits and satisfaction with life.

We investigated gene-environment interaction in ADHD traits, focusing on environmental variables related to personality traits, school environment, satisfaction with life, and callousness. Using data from 2170 16-year-old twins and state-of-the-art methodology to prevent spurious findings due to measurement scale artifacts, gene-environment interaction models were estimated separately for the two core ADHD dimensions, hyperactivity-impulsivity, and inattentiveness. Based on scores on the SWAN questionnaire, where high scores are reflective of low ADHD traits, results showed that additive genetic influences were more important in explaining individual differences in the degree of hyperactivity-impulsivity in twins with a high score on the trait conscientiousness than in twins with a moderate or low score (e.g., a positive gene-environment interaction). Similarly, additive genetic influences were relatively more important in explaining individual differences in the degree of inattentiveness in twins with a high score on conscientiousness or satisfaction with oneself. Lastly, a negative gene-environment interaction was found: For twins with a high score on the trait callousness, additive genetic influences were less important in explaining differences in the degree of inattentiveness than in twins with an average or low score on the trait. The finding of these specific gene-environment interactions is important for a deeper understanding of the etiology of ADHD traits and may assist in developing targeted interventions for genetically vulnerable individuals.