Saccade latency and accuracy were tested in 50 normal subjects (6-35 years), 19 ADHD patients (6-11 years), and 4 patients with frontal lesions (13-15 years) in an investigation of reflexive/voluntary control of saccades in ADHD, at University of Yamanashi, Japan. Subjects were seated in a dental chair with a chin rest in the dark, facing a display 100 cm away. A central fixation point (FP) appeared in the straight-ahead position, and visual targets were presented at 20 degrees to right or left of FP. Saccade tasks involved visually-guided (VGST), memory-guided (MGST), and antisaccade tasks. In normal controls, saccade latency and accuracy error rates were significantly correlated with age and maturity. The ADHD group showed significantly higher percentage of anticipatory errors and direction errors. Saccade eye movements do not fully mature until adolescence, and ADHD patients show dysfunction in “response inhibition”, which is modulated by the frontal lobe. [1]
COMMENT. The core symptoms of ADHD result from failure to inhibit or delay appropriate behavioral responses to stimuli. Evidence of faulty inhibition in ADHD is demonstrated by neuropsychological tasks (Go/NoGo, delayed response task, Stroop Color Word Interference Test), and from neuroimaging studies (MRI, SPECT, PET, and functional MRI). Abnormal saccade eye movements provide further evidence of frontostriatal dysfunction in children with ADHD.