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 .
Caffeine effects on resting-state electrodermal levels in AD/HD suggest an anomalous arousal mechanism
The effect of a single oral dose of caffeine was examined in a r and omised double-blind placebo-controlled repeated- measures cross-over study . Eighteen children with AD/HD , aged between 8 and 13 years , were individually age- and gender-matched with a control group . All children participated in two sessions , one week apart . Skin conductance level ( SCL ) from a 3 min eyes-closed epoch , commencing 30 min after ingestion of caffeine or placebo , was examined . Across conditions , mean SCL was lower in the AD/HD group than controls , confirming hypoarousal in AD/HD . Caffeine produced an increase in SCL , and this increase did not differ between the groups . However , arousal increases were dose-dependent in controls , but not in AD/HD . Rather , caffeine-induced arousal increases in the AD/HD group were positively related to their hyperactivity/impulsivity levels . This suggests an anomalous arousal mechanism in AD/HD functionally related to impairment in one symptom dimension
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 .