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The article presents a study in the U.S., which compares the effects of methylphenidate on attention-deficit/hyperactivity disorder (ADHD) subtypes. The researchers included 19 ADHD/inattentive and 22 ADHD/combined in the research and 34 unmedicated controls were tested at comparable time points. It was revealed that controls had better arithmetic performance than children with ADHD/C, who outperformed children with ADHD/I. Methylphenidate ameliorated task-incompatible behavior, arithmetic performance, and inattention comparably in both ADHD subtypes, whereas medication reduced hyperactivity and aggression in children with ADHD/C.

: BackgroundWe investigated the impact of stimulus probability and sequence on performance and event-related potentials of 310 children classified into 12 combinations of attention-deficit/hyperactivity disorder (Not–attention-deficit/hyperactivity disorder, Inattentive and Combined subtypes) with presence/absence of reading disorder and math disorder.: MethodsSubjects pressed buttons to displays of the letters O and X, which were presented with probabilities of either .17/.83 or .50/.50. Greater response selection was required in the .17/.83 condition.: ResultsStimulus probability had comparable effects on all diagnostic groups. The extent of mismatch between a stimulus and preceding events elicited less systematic increases in errors, P3b latency, and P3b amplitude among both attention-deficit/hyperactivity disorder subtypes than controls. Mismatch with preceding trials more greatly reduced math disorder and reading disorder + math disorder children’s speed in the Rare task and accuracy in both conditions. Math disorder and reading disorder + math disorder subjects also registered less the effects of alternations of the infrequent O on N2 amplitude and on P3b latency.: ConclusionsMath disorder and reading disorder + math disorder youngsters’ lower sensitivity to sequence irregularity in their event-related potentials along with greater disruption of performance suggest working memory deficits that adversely affected response selection. Comorbidity of attention-deficit/hyperactivity disorder and reading disorder did not affect the results. [ABSTRACT FROM AUTHOR]

Focuses on a study which evaluated deficits of executive functions in children with attention-deficit/hyperactivity disorder (ADHD). Comorbidity of ADHD; Comorbidity with oppositional defiant disorder and reading disorder; Methods of the study; Results and discussion; Limitations and clinical implications.