Caffeine effects on resting-state electrodermal levels in AD/HD suggest an anomalous arousal mechanism

• Published in: Biological psychology 2012-03, Vol.89 (3), p.606-608
• Main Authors: Barry, Robert J., Clarke, Adam R., McCarthy, Rory, Selikowitz, Mark, MacDonald, Brett, Dupuy, Franca E.
• Format: Article
• Language: English
• Subjects: AD/HD; Adolescent; Analysis of Variance; Arousal; Attention Deficit Disorder with Hyperactivity - drug therapy; Attention Deficit Disorder with Hyperactivity - physiopathology; Attention deficit disorders. Hyperactivity; Attention-Deficit/Hyperactivity Disorder; Behavioral psychophysiology; Biological and medical sciences; Caffeine; Caffeine - therapeutic use; Case-Control Studies; Central Nervous System Stimulants - therapeutic use; Child; Child clinical studies; Children; Cross-Over Studies; Dose-Response Relationship, Drug; Double-Blind Method; Female; Fundamental and applied biological sciences. Psychology; Galvanic Skin Response - drug effects; Humans; Male; Medical sciences; Neuropharmacology; Pharmacology. Drug treatments; Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer; Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer..., (alzheimer disease); Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Psychopathology. Psychiatry; Psychopharmacology; Reaction Time - drug effects; Rest - physiology; Skin conductance level
• ISSN: 0301-0511; 1873-6246
• DOI: 10.1016/j.biopsycho.2012.01.004

► Impaired arousal level (hypoarousal) was found in AD/HD compared with controls. ► Caffeine increased SCL/arousal similarly in AD/HD and controls. ► Controls showed a linear dosage effect, but AD/HD children did not. ► AD/HD SCL increase was linked with hyperactivity/impulsivity symptom score. ► This link suggests an impaired arousal mechanism underlying one symptom dimension. The effect of a single oral dose of caffeine was examined in a randomised 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 3min eyes-closed epoch, commencing 30min 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.