Our literature review identified ANS dysfunction in individuals with ADHD , more often in the direction of hypo-arousal than hyper-arousal , particularly at rest and during tasks requiring response regulation and sustained attention .
Stimulant medications  increased ANS activity and , in some studies , reinforcers and rewards produced a similar effect , suggesting that ANS function can be modified in ADHD .
Although arousal mechanisms have frequently been found to be atypical in ADHD , these findings usually emerged from indirect behavioural measures which give only a limited underst and ing of arousal dysregulation in this condition .
Responses to methylphenidate in adolescent AD/HD: evidence from concurrently recorded autonomic (EDA) and central (EEG and ERP) measures.
This paper aims to examine the effects of methylpheni date ( MPH ) on integrated baseline and event-related psychophysiological measures in AD/HD . Thirty-four unmedicated AD/HD adolescents ( 11 - 17 years ; 6 females ) were first compared to 34 age- and sex-matched controls , and then re-tested at least 4 weeks after methylpheni date ( MPH ) medication .  In each testing session , EDA was recorded simultaneously with EEG during a resting eyes open condition , and with ERPs during an auditory oddball task . Unmedicated AD/HD subjects were compared to controls and then AD/HD subjects were compared pre- and post-medication . Correlations between the change in EEG theta and the remaining psychophysiological variables were undertaken to provide information about post MPH treatment changes . In the unmedicated state , AD/HD was characterized by abnormally enhanced theta , across fronto- central sites , generally reduced P2 responses , with larger non-specific and oddball-elicited SCRs and poor behavioural performance on the oddball task . Following treatment , AD/HD showed a ' normalization ' of theta activity ( particularly in the right hemisphere ) , a reduction in the rate of decrement of EDA and a general increase in P3 amplitude . These findings suggest that methylpheni date is associated with a robust ' normalization ' of low frequency EEG activity during the resting brain state , but has less impact on task-related brain activity or phasic changes in autonomic function . This dissociation of resting and task-related activity may prove to be useful in elucidating the effects of stimulant versus new non-stimulant medications in AD/HD
Our literature review identified ANS dysfunction in individuals with ADHD , more often in the direction of hypo-arousal than hyper-arousal , particularly at rest and during tasks requiring response regulation and sustained attention .
Stimulant medications  increased ANS activity and , in some studies , reinforcers and rewards produced a similar effect , suggesting that ANS function can be modified in ADHD .
Although arousal mechanisms have frequently been found to be atypical in ADHD , these findings usually emerged from indirect behavioural measures which give only a limited underst and ing of arousal dysregulation in this condition .