Perfil cognitivo, ritmo e padrões do sono em pacientes portadores de esquizofrenia

Abstract

Clinical characteristics and symptom severity are heterogeneous in schizophrenia making the course and outcome less predictable. Sleep disturbances have been frequently described in association with this illness and may have deleterious effect on functional abilities. A few studies have described circadian changes in schizophrenia and some suggest a relationship between circadian alterations and poor performance after neuropsychological tests. Previously, it has been shown that patients with schizophrenia have impairment of verbal and visual-spatial working memory. However, many of these tests are laborious, complicated and time consuming. The utility of the several available neuropsychological tests in schizophrenia is not yet totally clarified. We have aimed to study sleep alterations, morning-evening preference, neurognitive function and their relationship with clinical variables. This is a cross-sectional study of patients with schizophrenia on use of conventional or atypical antipsychotic regarding functional abilities, sleep alterations and cognitive function. Assessment procedures involved the use of the Global Assessment of Functioning (GAF) Scale, Cumulative Illness Rating Scale (CIRS), Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Horne e Östberg questionnaire, and a neuropsychological battery that included the WAIS Digit Span Forward and Backward, Corsi block-tapping task (Forward and Backward), Stroop Color Word Interference Test and the Phonemic Verbal Fluency Test. We studied 82 patients (51.2% male) aged 17 to 59 years (35.2±10.4). Twenty-two were using conventional antipsychotic, 30 olanzapine and 30 risperidone. Poor sleep quality (PSQI>6) was observed in 41 subjects (50%) and excessive daytime sleepiness (ESE≥10) in 20 (24.4%). Female gender was associated with poor sleep quality (P=0.01). A trend of association between quality of sleep and GAF was observed (P=0.07). Worse disability, as evaluated by GAF, was associated with age, reduced number of school years and greater comorbidity severity. In relation to morning-evening preference, eight patients (9.8%) were definitely evening, 39 (47.6%) were moderately evening 33 (40.2%) were indifferent, 2 (2.4%) were moderately morning and none were definitely morning type. Younger patients and of male gender showed more evening preference (F= 6.32; P= 0.01) similar to previous reports in the literature. Frequent comorbidities were related to osteoarticular complaints, psychological symptoms, and metabolic alterations. Neuropsychological tests were altered in the vast majority of patients with values below 80% of historical normal values. The Stroop test was associated with GAF after controlling for age and school years (F= 6.43; P= 0.001). The Digit Span Backward was associated with GAF after controlling for gender, school years and type of antipsychotic (F= 4.76; P= 0.003). The Corsi block-tapping task Forward was associated with GAF after controlling for gender (F= 3.68; P= 0.01). The Corsi block-tapping task Backward was associated with GAF after controlling for gender, number of school years and type of antipsychotic (F=3.03; P= 0.02). The Stroop and Digit Span Backward were best associated with functional ability followed by the Corsi block-tapping task (Forward and Backward). A correlation between female gender and visual-spatial memory as evaluated by the Corsi Block-tapping Task Backward was observed. In conclusion, poor sleep quality is common and more present in women with schizophrenia. A trend between poor sleep quality and functional disability was observed. In general, an evening preference was predominant. Neurocognitive tests were altered in the majority of cases. The Stroop and Digit Span Indirect, two quick and easy to perform tests that evaluate working memory, were those that presented the greater association with global functional ability.