Cognitive, emotional, and social functioning of preschoolers with attention deficit hyperactivity problems

Attention Deficit Hyperactivity Disorder (ADHD) is associated with deficits in a number of functional domains, which have been described both as causes and effects of ADHD. It remains unclear if deficits in different domains are equally strong in early childhood, and which deficits are specific to ADHD. Here, we describe functional domains in preschoolers and assess deficits in children with ADHD problems, by comparing them to preschoolers who have other mental health problems or who develop typically. The ADHD Study assessed 1195 ca. 3.5 years old preschoolers through a semi-structured parent interview, parent questionnaires, and with neuropsychological tests. We determined functional domains by applying factor analytic methods to a broad set of questionnaire- and test-scales. Using resulting factor scores, we employed a Bayesian hierarchical regression to estimate functional deficits in children with ADHD. We found that preschoolers functioning could be described along the seven relatively independent dimensions activity level and regulation, executive function, cognition, language, emotion regulation, introversion, and sociability. Compared to typically developing preschoolers, those with ADHD had deficits in all domains except introversion and sociability. Only deficits in activity level and regulation and executive functions were larger than 0.5 standardized mean deviations and larger than deficits of children with other mental health problems. Preschoolers with ADHD have deficits in multiple functional domains, but only impairments in activity level and regulation and executive functions are specific for ADHD and large enough to be clinically significant. Research on functioning in these domains will likely be central for understanding the development of ADHD in later the childhood, and for improving treatment and prevention approaches.