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We administered the Tower of Hanoi to demographically comparable samples of control participants (n = 34) and children with the Combined (n = 22) and Inattentive subtypes (n = 19) of Attention-Deficit/Hyperactivity Disorder (ADHD). Controls excelled over children with the Inattentive subtype, who outperformed patients with the Combined subtype. These results replicated findings of greater executive deficits in the Combined than in the Inattentive type of ADHD. Double-blind administration of methylphenidate improved task performance only for patients with the Inattentive subtype. In a drug-free Baseline session, children with both subtypes of ADHD made more private verbalizations than controls, particularly when failing puzzles. In later sessions, regardless of drug condition, the inattentive sample exhibited a smaller increase in self-regulatory utterances under failure. In contrast, the combined sample decreased self-regulatory verbalizations under failure only under methylphenidate. The results support some differences between the two subtypes of ADHD in executive functioning and in their response to stimulant therapy.

This paper selectively reviews research on event-related potentials (ERPs) during cognitive processing among children with attention deficit disorder. Research indicates that performance deficits during sustained attention are coupled with reduced amplitude of the P3B component of the ERP, which may be increased with stimulants. P3B latency and selective attention are also reviewed. (Author/JDD)

We administered the Tower of Hanoi to demographically comparable samples of control participants (n = 34) and children with the Combined (n = 22) and Inattentive subtypes (n = 19) of Attention-Deficit/Hyperactivity Disorder (ADHD). Controls excelled over children with the Inattentive subtype, who outperformed patients with the Combined subtype. These results replicated findings of greater executive deficits in the Combined than in the Inattentive type of ADHD. Double-blind administration of methylphenidate improved task performance only for patients with the Inattentive subtype. In a drug-free Baseline session, children with both subtypes of ADHD made more private verbalizations than controls, particularly when failing puzzles. In later sessions, regardless of drug condition, the inattentive sample exhibited a smaller increase in self-regulatory utterances under failure. In contrast, the combined sample decreased self-regulatory verbalizations under failure only under methylphenidate. The results support some differences between the two subtypes of ADHD in executive functioning and in their response to stimulant therapy. [ABSTRACT FROM AUTHOR]

Studies the effects of stimulants on children with attention deficit disorders. Background on the study; Slowing during and after an error; Description of methods used in the study.

This study compared the impact of methylphenidate on patients with Attention-deficit Hyperactivity Disorder (ADHD) with and without aggressive/noncompliant features in an oddball test consisting of a randomly ordered series of loud (frequent) tones, soft (rare) tones, bright (frequent) lights, and dim (rare) lights. In alternate conditions, subjects were required to respond to either the rare tones or the rare lights. These tasks were administered in a drug-free baseline session and after a counterbalanced treatment of 14 days each of methylphenidate (0.3 mg/Kg b.i.d.) and placebo (lactose b.i.d.). In comparison with placebo, methylphenidate resulted in greater accuracy and speed of reactions to targets of both modalities. The amplitude of N1 to auditory nontargets was larger when the target was a rare tone as opposed to a rare light, and this attention-related effect was increased by methylphenidate. The same differential amplitude enhancement by stimulant treatment was found for an early area measure of difference ERPs. In contrast, for N1 to visual nontargets the effect of selective attention (larger amplitude when the target was a rare light vs. a rare tone) was not significant and was not affected by stimulant medication. All these findings were comparable for the three ADHD subgroups, a result attesting to the generality of stimulant effects on information processing. [ABSTRACT FROM AUTHOR]

Evoked potentials during the X and B-X versions of the Continuous Performance Test (CPT) were evaluated in 29 hyperactive children after ingestion of placebo or methylphenidate (0.3 mg/Kg). Twenty-one age matched normal children were also assessed twice but without any drugs. In both tests, placebo-treated hyperactives made more omission and commission errors and displayed smaller late positive components (LPC) of the evoked response to salient experimental cues. Methylphenidate ameliorated hyperactives' performance in both tasks and enlarged their LPCs in CPT-X. Several of these drug effects and diagnostic differences were absent for older hyperactive subjects, probably because some of the procedures were too easy for them. For younger patients the present tasks were sufficiently challenging, and the results reflect normalization of their deficits in sustained attention. [ABSTRACT FROM AUTHOR]

Presents a study that examines the clinical and cognitive effects of stimulants on children with attention deficit disorder (ADD). Assessment of information-processing deficits and their amelioration by stimulants; Comparison of the cognitive effects of methylphenidate in ADD children with and without aggressive/oppositional features; Results.

Twenty-two normal young men received a counterbalanced and double blind administration of 20 mg methylphenidate and placebo. Two tasks were administered in counterbalanced order: an uninterrupted 45-min vigilance test and a paired-associates learning test. As previously reported, under placebo, accuracy and speed decreased monotonically over the course of the vigil. This degradation of performance was significantly reduced by the stimulant drug. Event-related potentials (ERPs) were derived for correctly detected targets and nontargets. The most salient pharmacologic effects involved a late positive wave (P464) identified as P3b. Methylphenidate reversed or reduced the decrease in amplitude and increase in latency of P464 present over phases of the placebo session. The results suggest that the stimulant-induced improvement in performance may be mediated by enhancement of evaluation processes. In the paired-associates test there were no pharmacologic effects. Instead there was an unexpected, pronounced improvement in learning in the second session, irrespective of the substance administered. However, the ERP evoked by the "stimulus" cue of each pair was systematically related to the achievement of learning criteria. A late positive wave identified as P3b (P555) increased significantly in amplitude following the attainment of learning. There were no amplitude changes among ERPs evoked in the early post-criterion, late post-criterion, or overlearning "phases.'' Nor were there amplitude changes between early and late pre-criterion categories. Thus, ERP amplitude displayed a binary association with the achievement of learning. [ABSTRACT FROM AUTHOR]