Graph analysis of dream reports is especially informative about psychosis

Analyzing speech graphs from dream reports can distinguish people with schizophrenia from those with bipolar disorder and non-psychotic controls. People with schizophrenia showed reduced speech connectivity in both waking and dream reports, which correlated with negative and cognitive symptoms. People with bipolar disorder were indistinguishable from controls in waking reports but showed significantly less connectivity in dream reports. Dream-related speech graph attributes outperformed psychometric scores and waking data for sorting groups. The findings suggest that dreaming exposes differences in memory processing across individuals while waking dampens distinctions, and point toward a fast, low-cost, language-invariant tool for psychiatric diagnosis.

Study at a glance

Abstract

Early psychiatry investigated dreams to understand psychopathologies. Contemporary psychiatry, which neglects dreams, has been criticized for lack of objectivity. In search of quantitative insight into the structure of psychotic speech, we investigated speech graph attributes (SGA) in patients with schizophrenia, bipolar disorder type I, and non-psychotic controls as they reported waking and dream contents. Schizophrenic subjects spoke with reduced connectivity, in tight correlation with negative and cognitive symptoms measured by standard psychometric scales. Bipolar and control subjects were undistinguishable by waking reports, but in dream reports bipolar subjects showed significantly less connectivity. Dream-related SGA outperformed psychometric scores or waking-related data for group sorting. Altogether, the results indicate that online and offline processing, the two most fundamental modes of brain operation, produce nearly opposite effects on recollections: While dreaming exposes differences in the mnemonic records across individuals, waking dampens distinctions. The results also demonstrate the feasibility of the differential diagnosis of psychosis based on the analysis of dream graphs, pointing to a fast, low-cost and language-invariant tool for psychiatric diagnosis and the objective search for biomarkers. The Freudian notion that "dreams are the royal road to the unconscious" is clinically useful, after all.