Objectives. To assess and compare selected neuropsychological functions in a group of patients with schizophrenia, their healthy first-order relatives, and unrelated healthy controls.
Method. Participants in the study (n = 94) were: 34 patients diagnosed with schizophrenic psychosis (18 men, 16 women), 30 of their healthy first-order relatives (8 men and 22 women), and 30 healthy controls from the general population (13 men, 17 women). The patients were assessed during remission (none or minimalpsychotic symptoms). Their mean length of illness was differentiated (about 13±8years). Cognitive functions were assessed using a number of tests of attention and memory selected from the Vienna Test System (VTS, Schuhfried), more or less associated with the working memory function: the Visual Pursuit Test (LVT), the Corsi Block Tapping Test (CORSI), and the Stroop Interference Test (STROOP). Differences in the test performances were assessed using analysis of variance and post hoc tests of least significant difference (LSD).
Results. On all the tests of neuropsychological functions patients with schizophrenia had the lowest mean scores, while the best performance was noted in unrelated healthy controls. Healthy first-order relatives' performance scores were between these of the other two groups. Analysis of variance showed significant differences between the three groups in almost all the indicators under study. Between-group post hoc testing mostly confirmed significance of the differences between the three comparedgroups. However, there were also some interesting exceptions: in the CORSI test of visual short-term memory span neither the performance time nor the number of memorized items significantly differed the patients and their healthy relatives. Besides, in all parts of the STROOP Interference Test there were no significant differences in the number of erroneous responses between the patients' healthy relatives and healthy unrelated controls. Test scores were moderately correlated with length of illness (negatively) and with years of education (positively). Both these variables were intercorrelated (r = -0.38).
Conclusions. (1) As regards neuropsychological indicators under study, patients with schizophrenia performed poorest, while healthy controls showed the best performance. (2) Relatives of schizophrenic patients usually had intermediate scores - however, they did not differsignificantly from thepatients in the yisual short-term memory capacity, and theirperformance on color-word interference tasks did not differ from that of healthy controls. (3) The findings can be interpreted as not at variance with a hypothesis about endophenotypical character of the analyzed neuropsychological dysfunctions of attention and memory (and probably related working memory disturbances), regarded as a risk factor for schizophrenic psychosis. Such an interpretation should be treated with caution, especially due to the limited representativeness of the groups under study, as well as to the effect of education level and age.