The influence of three months of methylphenidate treatment on platelet-poor plasma biogenic amine levels in boys with attention deficit hyperactivity disorder.

Abstract

Attention deficit hyperactivity disorder (ADHD) is related to dysregulation in the activity of brain monoamines. The aim of the present study was to assess the impact of three months' methylphenidate (MPH) treatment on platelet-poor plasma (PPP) norepinephrine (NE), dopa and serotonin (5-HT) levels as well as on ADHD symptomatology. Three months of MPH treatment in 16 ADHD boys, aged 11.4 +/- 1.6 years, resulted in a significant reduction in PPP NE levels (p < 0.05). A tendency towards a reduction of PPP 5-HT and dopa levels was detected (p < 0.1 for both). The decrease in PPP biogenic amine levels after three months of MPH treatment was accompanied by a significant reduction in all psychometric characteristics of ADHD. This result indicates the possible role of overactivity of the noradrenergic system in the pathophysiology of ADHD and suggests that the MPH therapeutic action may be related to stimulant-induced inhibitory effect on the noradrenergic system. Copyright 2001 John Wiley & Sons, Ltd.