Associations between neurological soft signs, chronotype and sleep quality in schizophrenia

Abstract

Objective: Neurological soft signs (NSS) and sleep disorders are quite common in schizophrenia.Both symptom clusters have been proposed as candidate endophenotypes for the disorder. This study aimed to investigate the relationships between NSS, chronotype and sleep quality among patients with schizophrenia. Method: Positive and Negative Syndrome Scale (PANSS), The Neurological Evaluation Scale (NES), Morningness-Eveningness Questionnaire (MEQ), Pittsburgh Sleep Quality Index (PSQI), Beck Depression Inventory (BDI), and Beck AnxietyInventory (BAI) were administered to 50 patients with schizophrenia and 50 age- and gender-matched healthy control participants. Group differences were assessed using multivariate covariance models. We used stepwise multiple regression analysis to evaluate the potential relationships between NSS and clinical characteristics, diurnal preferences, sleep quality, anxiety, and depression in patients with schizophrenia. Results: Patients with schizophrenia were more likely to reveal severe impairments in NSS than healthy control participants even after controlling for demographic characteristics and the MEQ, PSQI, BAI, and BDI scores. In addition, patients were more prone to report evening-type characteristics than healthy individuals. Sleep disturbances were significant correlates of deficits in total NES, motor coordination, and other NSS. PSQI global and poor habitual sleep efficiency were associated with sequencing of complex motor acts. No relationships were found between NSS and chronotype. However, general psychopathology significantly contributed to NSS. Conclusion: The data showed that evening-type diurnal preferences and sleep quality as well as NSS seem to have complex implications in schizophrenia.