title: Are motor inhibition and cognitive flexibility dead ends in ADHD?
abstract: Executive dysfunction has been postulated as the core deficit in ADHD, although many deficits in lower order cognitive processes have also been identified. By obtaining an appropriate baseline of lower order cognitive functioning light may be shed on as to whether executive deficits result from problems in lower order and/or higher order cognitive processes. We examined motor inhibition and cognitive flexibility in relation to a baseline measure in 816 children from ADHD and control families. Multiple children in a family were tested in order to examine the familiality of the measures. No evidence was found for deficits in motor inhibition or cognitive flexibility in children with ADHD or their nonaffected siblings: Compared to their baseline speed and accuracy of responding, children with ADHD and their (non)affected siblings were not disproportionally slower or inaccurate when demands for motor inhibition or cognitive flexibility were added to the task. However, children with ADHD and their (non)affected siblings were overall less accurate than controls, which could not be attributed to differences in response speed. This suggests that inaccuracy of responding is characteristic of children having (a familial risk for) ADHD. Motor inhibition and cognitive flexibility as operationalized with mean reaction time were found to be familial. It is concluded that poorer performance on executive tasks in children with ADHD and their (non)affected siblings may result from deficiencies in lower order cognitive processes and not (only) from higher order cognitive processes/executive functions.
authors.affiliation: Department of Clinical Neuropsychology, Vrije Universiteit Amsterdam, Van der Boechorststraat 1, 1081 BT, Amsterdam, The Netherlands. nnj.rommelse@psy.vu.nl
authors.forename: Nanda N J
authors.initials: NN
authors.lastname: Rommelse
authors.forename: Marieke E
authors.initials: ME
authors.lastname: Altink
authors.forename: Leo M J
authors.initials: LM
authors.lastname: de Sonneville
authors.forename: Cathelijne J M
authors.initials: CJ
authors.lastname: Buschgens
authors.forename: Jan
authors.initials: J
authors.lastname: Buitelaar
authors.forename: Jaap
authors.initials: J
authors.lastname: Oosterlaan
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Sergeant
mesh_terms: D000293:Adolescent; D000328:Adult; D001289:Attention Deficit Disorder with Hyperactivity / Q000453:epidemiology* / Q000523:psychology; D002648:Child; D002675:Child, Preschool; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D015897:Comorbidity; D005260:Female; D006801:Humans; D008297:Male; D019957:Motor Skills Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D009426:Netherlands / Q000453:epidemiology; D011597:Psychomotor Performance; D011930:Reaction Time; D012307:Risk Factors; D035781:Siblings / Q000523:psychology