The effects of methylphenidate on prepulse inhibition during attended and ignored prestimuli among boys with attention-deficit hyperactivity disorder.
OBJECTIVE
The present study investigated attentional modification of prepulse inhibition of startle among boys with and without attention-deficit hyperactivity disorder (ADHD). Two hypotheses were tested: (1) whether ADHD is associated with diminished prepulse inhibition during attended prestimuli, but not ignored prestimuli, and (2) whether methylphenidate selectively increases prepulse inhibition to attended prestimuli among boys with ADHD.


METHODS
Participants were 17 boys with ADHD and 14 controls. Participants completed a tone discrimination task in each of two sessions separated by 1 week. ADHD boys were administered methylphenidate (0.3 mg/kg) in one session and placebo in the other session in a randomized, double-blind fashion. During each series of 72 tones (75 dB; half 1200-Hz, half 400-Hz), participants were paid to attend to one pitch and ignore the other. Bilateral eyeblink electromyogram startle responses were recorded in response to acoustic probes (50-ms, 102-dB white noise) presented following the onset of two-thirds of tones, and during one-third of intertrial intervals.


RESULTS
Relative to controls, boys with ADHD exhibited diminished prepulse inhibition 120 ms after onset of attended but not ignored prestimuli following placebo administration. Methylphenidate selectively increased prepulse inhibition to attended prestimuli at 120 ms among boys with ADHD to a level comparable to that of controls, who did not receive methylphenidate.


CONCLUSIONS
These data are consistent with the hypothesis that ADHD involves diminished selective attention and suggest that methylphenidate ameliorates the symptoms of ADHD, at least in part, by altering an early attentional mechanism.
Hawk
Larry W
LW
Department of Psychology, State University of New York, Park Hall Box 604110, Buffalo, NY 14260-4110, USA. lhawk@buffalo.edu
Yartz
Andrew R
AR
Pelham
William E
WE
Lock
Thomas M
TM
D001143:Arousal / Q000187:drug effects; D001288:Attention / Q000187:drug effects*; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000188:drug therapy* / Q000523:psychology; D001767:Blinking / Q000187:drug effects; D000697:Central Nervous System Stimulants / Q000627:therapeutic use*; D002648:Child; D004311:Double-Blind Method; D004576:Electromyography / Q000187:drug effects; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008774:Methylphenidate / Q000627:therapeutic use*; D010897:Pitch Discrimination / Q000187:drug effects*; D013216:Reflex, Startle / Q000187:drug effects
D000697:Central Nervous System Stimulants; D008774:Methylphenidate