Dream content in chronically-treated persons with schizophrenia

Abstract

Many clinical, laboratory and non-laboratory studies have examined dream content reported by patients with schizophrenia but findings have been variable and inconsistent. Using both questionnaire-based measures and laboratory REM sleep awakenings, we investigated dream content in 14 patients with schizophrenia (mean age=25.5+/-3.2 years) under atypical antipsychotic medication and 15 healthy controls (mean age=22.3+/-4.2 years). The relationship between eye movement density during REM sleep and dream content was also explored. Questionnaire data revealed that when compared to controls, patients with schizophrenia report experiencing a greater number of nightmares but no significant differences were found on other measures including overall dream recall, presence of recurrent dreams, and frequency of specific emotions. 39 dream reports were collected from each group following awakenings from REM sleep. Laboratory dream narratives from the patients were shorter and, after controlling for report length, most significant differences in dream content between the two groups disappeared with the exception of a greater proportion of unknown characters in the participant group. Patients with schizophrenia spontaneously rated their dream reports as being less bizarre than did controls, despite a similar density of bizarre elements as scored by external judges. Finally, both groups had a comparable density of rapid eye movements during REM sleep but a significant positive correlation between eye-movement density and dream content variables was only found in controls. Taken together, the findings suggest that dream content characteristics in schizophrenia may reflect neurocognitive processes, including emotional processing, specific to this disorder.