Alterations in cerebral laterality during acute psychotic illness.

A new dichotic listening test (fused rhymed words) was used to monitor changes in perceptual asymmetry (PA) in patients recovering from acute psychotic episodes; some were also given a dichotic nonsense syllables test, a dichotic tone test, and a single visual field dot localisation test. Contrary to expectation, PA on the word test decreased with recovery, while asymmetry on the tone and dot tests did not change; results cut across diagnosis, could not be related to medication, and were independent of changes in overall performance. More specific hypotheses are needed than those of generalised single hemisphere dysfunction in major psychiatric illness, but existing models and concepts are inadequate to explain the findings.