Effects of distractors on sustained attention in children with attention-deficit hyperactive disorder

OBJECTIVE: Using an experimental design combining the sustained attention task (CPT, SART) and the flanker task, we investigated: 1) whether children with attention-deficit hyperactive disorder (ADHD) have deficits in their sustained attention; 2) whether distractors have different effects on response to targets at different sustained attention levels; 3) whether different subtypes of ADHD children show different patterns in sustained attention. METHODS: Subjects were recruited from elementary school (Grade 2 - 6). Twenty seven ADHD children (23 male, 4 female) and 29 normal controls (24 male, 5 female) were matched by IQ and age. The cognitive experiment measuring reaction times and error rates was conducted on a computer using DMDX software. ADHD and normal children's performance in sustained attention and the effect of distractors were analyzed, and the results of subtypes of ADHD were compared. RESULTS: ADHD children and normal children did not show significant differences in error rates in their response to dominant (non-attentional) item. However, distractors impaired ADHD children's response to targets. ADHD children also showed more errors than normal children in the sustained attention task, but compared with the non-distractor condition, distractors facilitated their response. CONCLUSIONS: ADHD children have deficits in their sustained attention, reflecting the deficits in brain development. More importantly, this study found that the effects of distractors in sustained attention can be dissociated according to the level of demand on sustained attention: distractors interfered with responses to targets when the demand on sustained attention was low, and they facilitated responses to targets when the demand on sustained attention was high. There were no significant differences between ADHD-inattentive type and ADHD-combined type in their deficits in sustained attention.