Alterations in cerebral laterality during acute psychotic illness

Area of Science:

• Neuroscience
• Psychiatry
• Cognitive Psychology

Background:

• Cerebral laterality, the brain's functional specialization, is often altered in psychiatric disorders.
• Previous research suggests potential links between altered laterality and psychotic symptoms.

Purpose of the Study:

• To investigate the relationship between cerebral laterality and clinical state in patients with psychotic disorders.
• To determine if changes in laterality correlate with symptom severity and improvement.

Main Methods:

• Utilized a dichotic listening test to measure cerebral laterality in 26 patients with schizophrenia, schizoaffective, or major depressive disorder and 23 controls.
• Assessed clinical state using daily nurses' and patient self-ratings of psychotic thought and behavior.

Main Results:

• Psychotic symptoms were significantly lower during weeks of highest laterality and higher during weeks of lowest laterality (P < .01).
• Patients exhibited higher laterality when their condition improved compared to when most ill (P < .01).
• Changes in laterality were observed in patients but not controls, were independent of medication effects, and not linked to performance accuracy.

Conclusions:

• Findings support the hypothesis of a breakdown in interhemisphere inhibition during acute psychotic illness, affecting cerebral laterality.
• Fluctuations in laterality appear linked to the dynamic changes in psychotic symptom severity.