title: Working memory - not processing speed - mediates fluid intelligence deficits associated with attention deficit/hyperactivity disorder symptoms.
abstract: Attention deficit/hyperactivity disorder (ADHD) is a psychological condition characterized by inattention and hyperactivity. Cognitive deficits are commonly observed in ADHD patients, including impaired working memory, processing speed, and fluid intelligence, the three of which are theorized to be closely associated with one another. In this study, we aimed to determine if decreased fluid intelligence was associated with ADHD, and was mediated by deficits in working memory and processing speed. This study tested 142 young adults from the general population on a range of working memory, processing speed, and fluid intelligence tasks, and an ADHD self-report symptoms questionnaire. Results showed that total and hyperactive ADHD symptoms correlated significantly and negatively with fluid intelligence, but this association was fully mediated by working memory. However, inattentive symptoms were not associated with fluid intelligence. Additionally, processing speed was not associated with ADHD symptoms at all, and was not uniquely predictive of fluid intelligence. The results provide implications for working memory training programs for ADHD patients, and highlight potential differences between the neuropsychological profiles of ADHD subtypes.
authors.affiliation: School of Psychology & Exercise Science, Murdoch University, Perth, Western Australia, Australia.|Laboratory of Neuropsychology, University of the Balearic Islands, Palma de Mallorca, Spain.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Brydges
authors.affiliation: School of Psychology & Exercise Science, Murdoch University, Perth, Western Australia, Australia.
authors.forename: Krista L
authors.initials: KL
authors.lastname: Ozolnieks
authors.affiliation: School of Psychology & Exercise Science, Murdoch University, Perth, Western Australia, Australia.
authors.forename: Gareth
authors.initials: G
authors.lastname: Roberts
mesh_terms: D000293:Adolescent; D000328:Adult; D001289:Attention Deficit Disorder with Hyperactivity / Q000150:complications* / Q000523:psychology*; D060825:Cognitive Dysfunction / Q000150:complications* / Q000523:psychology*; D005260:Female; D006801:Humans; D007360:Intelligence; D008297:Male; D008570:Memory, Short-Term; D009483:Neuropsychological Tests; D011930:Reaction Time; D057566:Self Report; D055815:Young Adult
keywords: attention deficit/hyperactivity disorder; fluid intelligence; processing speed; working memory