Aim: Because of their importance both for pathogenesis or clinical aspects of the disease and for patients' social functioning, cognitive dysfunctions are nowadays often considered as basic characteristics of schizophrenic disorders. This study was aimed at evaluation of the correlation between some indices of disordered cognitive functioning on the one hand and some variables describing course and psychopathology of schizophrenic disorders on the other.
Method: The study group consisted of 69 inpatients suffering from schizophrenia diagnosed according to both DSM-IV and ICD-10 criteria. Their mental state was rated by two clinical tools (scales: PANSS, KOSS). Also social functioning of patients in the year preceding current hospitalisation was rated by two scales (GAF, scale W). Cognitive dysfunctions were assessed by computer-aided tests from Dr. Schufried's Vienna Test System including measures of reaction time (RT), visual line pursuit (LVT), perseveration (PERSEV), and span of visual-spatial short term memory (CORSI). In statistical analysis simple nonparametric tests and rank correlation measures were applied.
Results: Correlations were confirmed between cognitive dysfunctions and social functioning prior to hospitalisation, age, duration of illness and number of previous hospitalizations. Dysfunctions were less severe in first episode patients than in patients during relapses or the residuum stage of illness. Overall assessments of severity of illness do not correlate with cognitive dysfunctions, but detailed analysis of psychopathology revealed correlations of the latter with such psychopathological dimensions as deficit, disorganization and dysphoria. Reality distortion (positive) psychopathological dimension did not have any correlation with cognitive measures. All indices of cognitive dysfunction correlated with poorer outcome of treatment of the current episode. All correlations confirmed were only of weak or moderate level.
Conclusions: Cognitive dysfunctions correlate rather with unfavourable characteristics of the course of the illness. Results of psychopathological assessment hardly correlate with neuropsychological measures--cognitive dysfunctions are related rather to deficit (negative), disorganisation or dysphoria dimensions of a schizophrenic syndrome than to productive (reality distortion, positive) dimension of the syndrome.