Oades, R. D., & Christiansen, H., (2007).
Cognitive switching processes in young people with attention-deficit/hyperactivity disorder.
Arcives of Clinical Neuropsychology, 8, 122-131.[Request a copy] [view whole article]

Introduction: Children and adolescents with ADHD can be slow to switch between stimuli, or between sets of stimuli that control behaviour appropriate to changing situations.

Methods: We studied a range of clinical and experimental parameters that may influence the speed of such processes measured in the trail-making (TMT) and switch-tasks (after Cepeda) in patients with ADHD of the combined subtype, their siblings who did not have ADHD and unrelated healthy controls.

Results:
1 - The latency to finish the trail-making task (TMT form B) controlling for psychomotor processing (TMT form A) was longer for those with ADHD, and correlated with ratings of symptom severity on the Conners’ scales across all subjects -- The effect decreased with age.

2 - Switch-task responses to questions of “Which number?” and “How many?” between sets of 1/111 or 3/333 elicited differential increases in latency with condition that affected all groups. But we found increased symptom-related intra-individual variability among the ADHD cases.

3 - Young siblings showed familiality for some measures of TMT and switch-task performance but these were modest.

Discussion: The potential influences of moderator variables on the efficiency of processing stimulus change rather than the speed of processing are discussed.