Relationship of Attention-deficit Hyperactivity Disorder and Sleep Problems: an Event-related Potential Study
Date Issued
2010
Date
2010
Author(s)
Cheong, Pou-Leng
Abstract
Background and objectives
Attention-deficit/hyperactivity disorder (ADHD) is one of the most common childhood neurobehavioral disorders. Recent neuropsychological work has suggested that ADHD children may suffer from deficits in the frontal executive function on motor control. Sleep problems are frequently observed in children with ADHD but their relationship remains unclear. As some sleep problems can be treated instead of stimulants, assessment and treatment of sleep problems in potential ADHD patients before starting the long-term use of stimulants should be considered.
Event-related potentials (ERP) recording gives a spatio-temporal approach helping us to know variations of brain activity associated with the processes of attending to, anticipating, and detecting environmental targets as well as reflecting preparation to make a motor response.
Our objectives were to study the ERP components of these children (ADHD with sleep problems, ADHD only, sleep problems only and normal controls) so as to investigate the relationship of ADHD and sleep problems and the pathogenic mechanisms of ADHD and sleep problems.
Materials and methods
Materials
Children aged 6 to 12 years with the diagnosis of ADHD with or without sleep problems, sleep problems only and normal children were included, excluding those with IQ<80 or underlying psychiatric, mental or neurological disorders or developmental disabilities.
Methods
After completing the questionnaires, informed consents and neuropsychological tests, subjects took the EEG examination for the ERP measurements with the Posner cueing paradigm and the auditory oddball paradigm. Combined analysis of electrophysiological components (like P1, N2, P3, mismatch negativity (MMN) and contingent negative variation (CNV)) and behavioral data (reaction time (RT) and the number and percentage of errors) were done in the 4 groups. The behavioral data and ERP results will be assessed using repeated measures analysis of variance (ANOVA) and Fisher’s least significance test for multiple comparisons by the SAS 9.1 version.
Results and Discussion
The behavioral performance and ERP results of the 62 subjects were analyzed (15 with ADHD only, 17 with ADHD and sleep problems, 15 with sleep problems and 15 controls). No significant differences in age and FIQs were noted among these 4 groups. No significant differences in the SNAP-IV subscales (inattentive (IA), hyperactive/impulsive (HI)) were noted in the groups with ADHD except the total SNAP-IV (IA+HI+OP) scores. No significant differences in the proportions of the subtypes of sleep problems were noted in the groups with sleep problems except frequent leg movements during sleep.
About the behavioral performance, subjects with ADHD and sleep problems have the longest mean reaction time and more anticipation errors, suggesting greater impulsivity, poorer attention orienting and probably poorer coordination. Subjects with sleep problems have similar behavioral performance as our controls.
However, for the analysis of the ERP components, the amplitudes of the target-P1, the target-P3 components, MMN and CNV of the children with sleep problems only were the smallest. Besides, in those with ADHD, subjects with sleep problems had smaller amplitudes of the target-P1, target-P3, MMN and CNV than those without sleep problems. There was a smaller increment in the target-P1 amplitudes from valid to invalid condition in ADHD groups (22.7% and 31%) than non-ADHD groups (49% and 58%), suggesting poorer function in attention shifts in those ADHD subjects.
As subjects with sleep problems (with or without ADHD) have smaller target-P1, target-P3 and MMNs (MMN was considered as a frontal lobe sensitive ERP component), ADHD and sleep problems may both have frontal lobe deficits which may be associated with poor attention maintenance and disorders in arousal.
Conclusion
Though subjects with sleep problems showed similar behavioral performances as the controls, their ERP measurements were poorer than the controls and seemed to be similar to those with ADHD and sleep problems. Considering the behavior and electrophysiological results, the ADHD patients with sleep problems might have more severe frontal executive deficits than those with ADHD only and thus they might need more attention and aggressive intervention including behavioral therapy and stimulants. Besides, early insomnia might be an important sleep problem that might lead to ADHD-like symptoms and neurocognitive impairment. Further investigation with more confirmative diagnostic tools like K-SADS and polysomography (to lessen the heterogeneity of sampling) and increased sample size and tasks might help us to have better understanding of the relationship between ADHD and sleep problems.
Subjects
attention-deficit hyperactivity disorder
sleep problems
event-related potentials
P3
mismatch negativity
contingent negative variation
Type
thesis
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