Eye movement and neuropsychological studies in first-degree relatives of schizophrenic patients

The aim of the study was to compare the results of oculomotor and neuropsychological tests in first-episode schizophrenic patients, in both their parents and matched healthy controls. Eye movement tests included fixation and a smooth pursuit task and neuropsychological tests which comprised the Trail Making Test (TMT) A and B, the Stroop Test A and B, and the Wisconsin Card Sorting Test (WCST). There was a significant difference between the 21 patients and their 33 healthy parents in the results of both the eye movement tests and the TMT and WCST but not in the Stroop test. On the other hand, a significant difference between parents and their matched control subjects was found in both oculomotor tests, in the Stroop B, and in two indices of the WCST (completed categories, CC and percentage of conceptual level responses, %CONC). A correlation was obtained between patients and their fathers in the intensity of smooth pursuit disturbances and two indices of the WCST (CC and %CONC), but not between patients and their mothers. The results obtained confirm those of other studies pointing to the presence of a significant impairment on oculomotor and neuropsychological tests in first-degree nonpsychotic relatives (parents) of schizophrenic patients, which may be used as an endophenotypic markers of genetic predisposition to schizophrenia.