Interaction of symptoms and cognitive dysfunction in remitted schizophrenic patients with and without residua – important sign of heterogeneity for design of cognitive enhancer studies

Introduction It is well-known fact that cognitive dysfunction (CD) determines the quality of remission in patients with schizophrenia. However many attempts to demonstrate the link between symptoms and CD failed. The reason for this fact is unclear. Objectives Heterogeneity on basis of the important sign jeopardizes the signal detection. Aims Assessment of interaction between clinical symptoms and CD in schizophrenic patients in remission with and without residual psychotic symptoms (RPS). Methods Adult schizophrenic patients in remission with and without RPS (DSM 295.30) on stable treatment not less than 6 months were assessed with PANSS, CGI, BACS. The indices of the testing were compared between groups. The correlation analysis was performed. The correlation was considered significant if R  u003e 0.60. Results Ten females and 34 males were divided into two groups according to presence (27 patients) or absence (17 patients) of RPS (PANSS items P1 and P3 u003e 2 but  P  = 0.0005), P20 ( P  = 0.007), P23 ( P  = 0.0004), and positive subscale PANSS ( P  = 0.00001). In the group without RPS, we found that CGI score, scores of 10 items of PANSS, scores of PANSS subscales, excluding negative subscale, and total PANSS score highly negatively correlated with total BACS score (average R  = –0.70 ± 10). In the group of patients with RPS, no correlations were found. Conclusions Patients with RPS has clinical significant dissociation of psychic and cognitive functioning that should be considered in planning, and assessing of results of cognitive enhancers studies.