Asymmetrical hemispheric control of visual-spatial attention in adults with attention deficit hyperactivity disorder.

As neuropsychological mechanisms for attention have been hypothesized to be located in the right hemisphere of the brain, several investigators have begun to conceptualize attention deficit hyperactivity disorder (ADHD)-related attentional deficits as involving right-hemispheric abnormalities. The authors evaluated and compared adult patients diagnosed with ADHD with a non-ADHD group of patients using a chronometric visual-spatial attention task that is sensitive to hemispheric differences in efficiency of information processing. Reaction times across different cuing conditions, cue-target delays, and visual fields were assessed. When participants' attention was misdirected with cues in the right visual field and attention had to be switched to a target on the left visual field, there was a longer delay among ADHD adults than non-ADHD adults, specifically when the interval between the cue and target was 800 ms as compared with 100 ms. This specific pattern of dysfunction was interpreted as a difficulty with maintaining attention possibly associated with anterior attention mechanisms in the right hemisphere.