Dissociation in performance of children with ADHD and high-functioning autism on a task of sustained attention.
Attention deficit hyperactivity disorder (ADHD) and autism are two neurodevelopmental disorders associated with prominent executive dysfunction, which may be underpinned by disruption within fronto-striatal and fronto-parietal circuits. We probed executive function in these disorders using a sustained attention task with a validated brain-behaviour basis. Twenty-three children with ADHD, 21 children with high-functioning autism (HFA) and 18 control children were tested on the Sustained Attention to Response Task (SART). In a fixed sequence version of the task, children were required to withhold their response to a predictably occurring no-go target (3) in a 1-9 digit sequence; in the random version the sequence was unpredictable. The ADHD group showed clear deficits in response inhibition and sustained attention, through higher errors of commission and omission on both SART versions. The HFA group showed no sustained attention deficits, through a normal number of omission errors on both SART versions. The HFA group showed dissociation in response inhibition performance, as indexed by commission errors. On the Fixed SART, a normal number of errors was made, however when the stimuli were randomised, the HFA group made as many commission errors as the ADHD group. Greater slow-frequency variability in response time and a slowing in mean response time by the ADHD group suggested impaired arousal processes. The ADHD group showed greater fast-frequency variability in response time, indicative of impaired top-down control, relative to the HFA and control groups. These data imply involvement of fronto-parietal attentional networks and sub-cortical arousal systems in the pathology of ADHD and prefrontal cortex dysfunction in children with HFA.
Johnson
Katherine A
KA
School of Psychology and Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland. johnsoka@tcd.ie
Robertson
Ian H
IH
Kelly
Simon P
SP
Silk
Timothy J
TJ
Barry
Edwina
E
Dáibhis
Aoife
A
Watchorn
Amy
A
Keavey
Michelle
M
Fitzgerald
Michael
M
Gallagher
Louise
L
Gill
Michael
M
Bellgrove
Mark A
MA
D000293:Adolescent; D000818:Animals; D001288:Attention / Q000502:physiology*; D001289:Attention Deficit Disorder with Hyperactivity / Q000503:physiopathology*; D001321:Autistic Disorder / Q000503:physiopathology*; D002648:Child; D002755:Choice Behavior / Q000502:physiology; D004213:Dissociative Disorders / Q000209:etiology*; D006801:Humans; D007266:Inhibition, Psychological; D016014:Linear Models; D008297:Male; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000502:physiology; D013057:Spectrum Analysis; D013647:Task Performance and Analysis