Interstimulus jitter facilitates response control in children with ADHD

Interstimulus "jitter" involves randomization of intervals between successive stimulus events, and can facilitate performance on go/no-go tests among healthy adults, though its effect in clinical populations is unclear. Children with Attention-defi cit/Hyperactivity Disorder (ADHD) commonly exhibit defi cient response control, leading to increased intra-subject variability (ISV), which has been linked to anomalous functioning within frontal circuits, as well as their interaction with posterior "default mode" regions. We examined effects of interstimulus jitter on response variability in 39 children, ages 9-14 years (25 ADHD, 14 controls). Participants completed 2 computerized go/no-go tests: one with fi xed interstimulus interval (ISI) and one with jittered ISI. Repeated measures analysis of variance (ANOVA) revealed a signifi cant group-by test interaction, such that introduction of jitter produced a signifi cant decrease in ISV among children with ADHD, but not among controls. Whereas children with ADHD were signifi cantly more variable than controls on the go/no-go test with fi xed ISI, their performance with jittered ISI was equivalent to that of controls. Jittering stimulus presentation provides a nonpharmacologic mechanism for improving response control in ADHD. This bottom-up approach may be mediated by increases in vigilance through noradrenergic circuits that facilitate maintenance of frontal circuits critical to response control.