Altered performance on an ocular fixation task in attention-deficit/hyperactivity disorder

Background: Attention-deficit/hyperactivity disorder (ADHD) is a common psy chiatric disorder without validated objective markers. Eye movement studies may be useful in providing objective criteria for characterizing the disor der. Methods: We compared 53 children (29 girls) with ADHD to 44 healthy control children (18 girls) on a 21-sec fixation task. Large saccades (> 4 degrees ) away from the fixation point were analyzed. Results: Children with ADHD made more large saccades that interrupted fixat ion than did control children (p =.001). Mean scores of the ADHD group did not change significantly with subsequent retesting on placebo (p =.11); how ever, there was poor intrasubject correlation (r =.16). Conclusions: Both boys and girls with ADHD made significantly more intrusiv e saccades during fixation than did control subjects, possibly, reflecting intrinsic neurologic dysfunction; however, a probable "floor effect" obviat es conclusions about the reliability, of this measure. (C) 2001 Society of Biological Psychiatry.