Saccadic distractibility in schizophrenia patients and their first-degree biological relatives.

다국어 초록 (Multilingual Abstract)

Among schizophrenia patients, performance deficits on antisaccade tasks are thought to reflect saccadic distractibility, a sign of prefrontal dysfunction. Two studies were conducted to evaluate this supposition. In study 1, 91 acute schizophrenia patients, 13 schizophrenia patients in full remission, 38 acute psychotic affective disorder patients, 108 first-degree biological relatives of the acute schizophrenia patients, and 104 nonpsychiatric controls, were administered antisaccade and prosaccade tasks. Both schizophrenia groups had an increased number of errors on the antisaccade task compared to the relative and affective group, who both had more errors than the controls. Regardless of clinical state, schizophrenia patients and their relatives show robust difficulties suppressing unwanted saccades during the antisaccade task. It is unlikely that saccadic distractibility was due to confounds such as interfering psychotic symptomatology, medication, or medication side effects. In addition, generalized problems with saccadic control could not account for their increased rate of reflexive errors on the antisaccade task. In study 2, 38 schizophrenia patients, 41 of their first-degree biological relatives, 23 psychotic affective disorder patients, and 30 non-psychiatric controls were administered three oculomotor tasks that varied in degree of requisite saccadic inhibitory load (fixation [low], fixation ion with distractors [medium], and antisaccade [high]). The presence of visible fixation stimuli and the significance of the distractors were parameters that varied the difficulty in suppressing unwanted saccades. The schizophrenia patients and their first-degree biological relatives showed robust evidence of increased saccadic distractibility that was most pronounced during high inhibitory load conditions. Together, these findings strongly suggest that saccadic distractibility is associated with the liability for schizophrenia.