title: Decreased frontal, striatal and cerebellar activation in adults with ADHD during an adaptive delay discounting task.
abstract: An important characteristic of childhood attention-deficit/hyperactivity disorder (ADHD) is a bias towards small immediate versus larger delayed rewards, but it is not known if this symptom is also a feature of adult ADHD. A delay-discounting task was administered to participants with adult ADHD and a comparison group in conjunction with functional magnetic resonance imaging. Participants responded to a series of questions that required judgments between small sums of money available immediately and larger sums obtained after a temporal delay. Question parameters were adjusted by an adaptive algorithm designed to converge on each participant's discounting indifference point, an individual set point at which there is equal valuation of both choices. In all participants, robust task activation was observed in regions previously identified in functional imaging studies of delay discounting. However, adults with ADHD showed less task activation in a number of regions including the dorsolateral prefrontal cortex, superior frontal gyrus, anterior cingulate, caudate nucleus and declive of the cerebellum. Additionally, the degree to which a participant discounted delayed rewards was inversely related to task activation in the cerebellum. The results suggest that the bias towards immediate rewards in childhood ADHD may not persist behaviorally, but instead present in adulthood as alterations in frontostriatal and frontocerebellar networks.
authors.affiliation: University of Vermont, Department of Psychiatry, Burlington, USA, hugh.garavan@uvm.edu.
authors.forename: Nick
authors.initials: N
authors.lastname: Ortiz
authors.affiliation: University College Dublin School of Psychology, Dublin, Ireland.
authors.forename: Aisling
authors.initials: A
authors.lastname: Parsons
authors.affiliation: University College Dublin School of Psychology, Dublin, Ireland.
authors.forename: Robert
authors.initials: R
authors.lastname: Whelan
authors.affiliation: University of Vermont, Department of Psychiatry, Burlington, USA.
authors.forename: Katie
authors.initials: K
authors.lastname: Brennan
authors.affiliation: University College Dublin School of Psychology, Dublin, Ireland.
authors.forename: Maria L F
authors.initials: ML
authors.lastname: Agan
authors.affiliation: Trinity College Dublin, Trinity College Institute of Neuroscience, Dublin, Ireland.
authors.forename: Redmond
authors.initials: R
authors.lastname: O'Connell
authors.affiliation: University College Dublin School of Psychology, Dublin, Ireland.
authors.forename: Jessica
authors.initials: J
authors.lastname: Bramham
authors.affiliation: University of Vermont, Department of Psychiatry, Burlington, USA.
authors.forename: Hugh
authors.initials: H
authors.lastname: Garavan
mesh_terms: D000328:Adult; D001289:Attention Deficit Disorder with Hyperactivity / Q000473:pathology* / Q000503:physiopathology*; D002531:Cerebellum / Q000098:blood supply / Q000503:physiopathology*; D003342:Corpus Striatum / Q000098:blood supply / Q000503:physiopathology*; D065786:Delay Discounting / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000098:blood supply / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D011569:Psychiatric Status Rating Scales; D055815:Young Adult
chemical_list: D010100:Oxygen