A Longitudinal Behavior Genetic Analysis of Inhibitory Control and ADHD Symptoms from Toddlerhood through Early Adolescence

Inhibitory control (IC) is a dimension of temperament and an executive function involving the ability to appropriately regulate behavior. In middle childhood, IC is negatively related to non-clinical behavior problems and... [ view full abstract ]

Inhibitory control (IC) is a dimension of temperament and an executive function involving the ability to appropriately regulate behavior. In middle childhood, IC is negatively related to non-clinical behavior problems and Attention Deficit Hyperactivity Disorder (ADHD). Multiple twin studies indicate that IC is genetically influenced, however findings depend somewhat on the age of the participants and the assessment methodology (Gagne & Saudino, 2010; 2016; Gagne & Goldsmith, 2011). Parent-ratings of IC show a much more stable and consistent etiology and developmental trajectory than do lab-based assessments. Researchers have also found genetic and environmental covariance between IC and externalizing behavior problems in toddlerhood (Gagne, Saudino & Asherson, 2011) and school age (Lemery-Chalfant, Doelger, Goldsmith, 2008). We examined the development and etiology of IC and ADHD from a multi-method perspective longitudinally from early childhood to adolescence

Participants included 101-245 MZ and 150-424 DZ twin pairs from the Wisconsin Twin Project. Mothers rated IC in todderhood (TBAQ) and first grade (CBQ), and mother ratings of DISC-ADHD symptoms were collected in first grade and again in early adolescence. Phenotypic correlations between IC and ADHD ranged from -.20 to -.68. MZ correlations exceeded DZ correlations, indicating genetic influences. Cross-twin, cross-trait correlations for MZ twins exceeded those for DZ twins suggesting genetic covariance between IC and ADHD. Initial bivariate Cholesky decomposition modelss of toddler IC and first grade ADHD, and first grade IC and early adolescent ADHD yielded genetic and nonshared environmental variances and covariances (genetic correlations between IC and ADHD ranged from -.19- -.24). Results show that toddler IC is phenotypically and etiologically associated with ADHD in first grade, as is first grade IC and early adolescent ADHD. Based on these findings, early IC can be considered a genetic risk factor for later ADHD symptoms. Future analyses will include laboratory-based behavioral assessments of IC in first grade.