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).

Katherine A. Johnson,ab* Ian H. Robertson,a Simon P. Kelly,ac Timothy J. Silk,def Edwina Barry,b Aoife Dáibhis,a Amy Watchorn,a Michelle Keavey,a Michael Fitzgerald,b Louise Gallagher,b Michael Gill,b and Mark A. Bellgroveag

Abstract

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.

Keywords: Response time, Fast Fourier transform, Variability, Arousal, Response inhibition, Executive function
 
The publisher’s final edited version of this article is available at Neuropsychologia.
 

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References

a School of Psychology and Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
b School of Medicine and Health Sciences and Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
c Cognitive Neurophysiology Laboratory, Nathan S. Kline Institute, Orangeburg, NY 10962, United States
d Howard Florey Institute and Centre for Neuroscience, University of Melbourne, Australia
e Academic Child Psychiatry Unit, Department of Pediatrics, University of Melbourne, Australia
f Department of Psychology, Monash University, Australia
g Cognitive Neuroscience Laboratory, School of Psychology and Queensland Brain Institute, University of Queensland, Brisbane, Australia
* Corresponding author at: School of Psychology and Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland. Tel.: +353 1 896 8403; fax: +353 1 671 2006. E-mail address: johnsoka@tcd.ie (K.A. Johnson).

Neuropsychologia. Author manuscript; available in PMC 2007 October 3.
Published in final edited form as: Neuropsychologia. 2007 June 11; 45(10): 2234–2245.
Published online 2007 March 4. doi: 10.1016/j.neuropsychologia.2007.02.019. PMCID: PMC2000292
UKMSID: UKMS975