Cognitive bizarreness in the dream and waking mentation of nonpsychotic patients with Parkinson's disease.

Cognitive bizarreness is a shared feature of the dream and waking mentation of acutely psychotic patients. The authors investigated this measure of the structural architecture of thought in the dream and waking mentation of 20 nonpsychotic patients with Parkinson's disease after treatment with prodopaminergic drugs. Statistically overlapping levels of cognitive bizarreness were found in the waking fantasy and dream reports of the Parkinson's disease population, whereas almost no bizarreness was found in the waking cognition of the comparison group, suggesting it may be an inherent quality of cognition in Parkinson's disease patients, possibly related to the cholinergic/dopaminergic imbalance underlying this complex disorder.

The dream as a model for psychosis: an experimental approach using bizarreness as a cognitive marker.

Many previous observers have reported some qualitative similarities between the normal mental state of dreaming and the abnormal mental state of psychosis. Recent psychological, tomographic, electrophysiological, and neurochemical data appear to confirm the functional similarities between these 2 states. In this study, the hypothesis of the dreaming brain as a neurobiological model for psychosis was tested by focusing on cognitive bizarreness, a distinctive property of the dreaming mental state defined by discontinuities and incongruities in the dream plot, thoughts, and feelings. Cognitive bizarreness was measured in written reports of dreams and in verbal reports of waking fantasies in 30 schizophrenics and 30 normal controls. Seven pictures of the Thematic Apperception Test (TAT) were administered as a stimulus to elicit waking fantasies, and all participating subjects were asked to record their dreams upon awakening. A total of 420 waking fantasies plus 244 dream reports were collected to quantify the bizarreness features in the dream and waking state of both subject groups. Two-way analysis of covariance for repeated measures showed that cognitive bizarreness was significantly lower in the TAT stories of normal subjects than in those of schizophrenics and in the dream reports of both groups. The differences between the 2 groups indicated that, under experimental conditions, the waking cognition of schizophrenic subjects shares a common degree of formal cognitive bizarreness with the dream reports of both normal controls and schizophrenics. Though very preliminary, these results support the hypothesis that the dreaming brain could be a useful experimental model for psychosis.