Relations between inhibition, executive functioning, and ADHD symptoms: a longitudinal study from age 5 to 8(1/2) years.

The present study examined whether inhibition measured as early as preschool can predict more general executive functioning and ADHD symptoms at school age. In contrast to previous studies, the present study focused specifically on ADHD symptoms rather than general disruptive behavior problems, and boys and girls were studied separately. The main result was that inhibition was strongly related to ADHD symptoms both in school and at home for boys, but only in the school context for girls. Early inhibition was also significantly related to later executive functioning, and concurrent relations were found between executive functioning and ADHD symptoms, although in both cases only for boys. Besides this, inhibition added significantly to the variance, beyond that of executive functioning, which meant that for boys, inhibition and the other executive functioning explained about half the variance in inattention problems. The stronger relation between inhibition, executive functioning and ADHD symptoms for boys compared to girls could suggests that either the predictors of ADHD are different for the two sexes, or girls are more often equipped with some factor that protects them from developing ADHD symptoms, despite poor executive functioning. However, it is also possible that relations are just harder to demonstrate for girls due to their lower incidence of disruptive problem behaviors.