The Relation Between ADHD and Cognitive Profiles of Children with NF1

Abstract

Despite well-accepted findings of a “downward shift” in intellectual functioning in children with neurofibromatosis type 1 (NF1), research has not examined the contribution of the individual indices in this lower performance on intelligence (IQ) measures. Although 30–50 % of children with NF1 meet criteria for a diagnosis of attention deficit/hyperactivity disorder (ADHD), research has not established the relation between ADHD and intellectual profiles in these children. To clarify these issues, this study examined the Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV) profiles of children with NF1, with and without comorbid ADHD, using a comparison group of children with developmental ADHD. We found that rather than an overall lowering of IQ, children with NF1 demonstrated an uneven intellectual profile. While verbal abilities were generally preserved, nonverbal, working memory, and processing speed abilities were lower than the population norms. Children with NF1 and comorbid ADHD showed significantly lower performance on tests of working memory than children with NF1 without ADHD or children with developmental ADHD. These results suggest that global intellect is inadequate in describing the cognitive phenotype in children with NF1 and that in children with NF1 comorbid ADHD may manifest as additional cognitive burden with respect to working memory.