[Attention in hyperkinetic children: a signal detection analysis of the effect of methylphenidate]

The effects of methylphenidate on sustained attention were investigated in a placebo-controlled double-blind trial with 20 hyperactive boys of normal intelligence with minimal brain dysfunction (MBD). Using signal detection theory methylphenidate significantly increased sensitivity (d) and did not change response bias (beta), independent of the dosage (5 to 20 mg/d). Responders and nonresponders to methylphenidate were differentiated by signal detection analysis: responders improved primarily in sensitivity, whereas nonresponders changed response bias. No response difference was found in physiological and biochemical measures (catecholamines), showing a general activation caused by methylphenidate. It is discussed that methylphenidate is improving information processing and arousal modulation in responders and is raising unspecific activation in nonresponders.