ADHD symptoms in children with mild intellectual disability.

OBJECTIVES

To determine whether the nature and correlates of attention-deficit/hyperactivity disorder (ADHD) symptoms are different in subjects with mild intellectual disability (ID) compared to subjects with average ability.

METHOD

From a general population sample of 2,726 12- to 15-year-olds, a stratified subsample was selected to enrich for mild ID. A total of 192 subjects were included in the analyses. ADHD symptoms and other emotional/behavioral problems were measured with the parent and teacher Strengths and Difficulties Questionnaire and IQ with the WISC-III-UK), and social communication difficulties were assessed by a short version of the Social Communication Questionnaire and academic attainments by the Wechsler Quicktest.

RESULTS

There was a negative linear relationship between ADHD symptoms and IQ (beta = -.087, p <.001). The relationship could not be explained by inappropriate rater expectations. Neither the profiles of ADHD symptoms nor the comorbidity with emotional/behavioral problems differed according to the presence of ID. When IQ was accounted for, the group difference in attainments was nonsignificant.

CONCLUSIONS

ADHD symptoms are increased in people with ID. We found no evidence that this increase can by explained by inappropriate expectations or by confounding associations with other emotional/behavioral or cognitive problems.