A meta-analysis by researchers from the University of Florence, Geneva University Hospital, and École Polytechnique Fédérale de Lausanne has identified a common brain alteration in patients with schizophrenia and bipolar disorder, supporting the concept of a shared “psychosis spectrum.”
The team systematically reviewed 96 brain imaging studies spanning three decades, involving thousands of participants. Using MRI data, they examined white matter, the brain’s communication pathways.
Both disorders showed shared white matter alterations in the corpus callosum, the structure connecting the brain’s hemispheres. This alteration appeared across the psychosis spectrum rather than being limited to a single diagnosis, and findings remained significant after accounting for age and sex.
While schizophrenia and bipolar disorder have traditionally been treated as distinct conditions, many patients with either disorder experience psychosis at some point. Recent research has revealed overlapping symptoms, genetic patterns, and brain organization, lending support to the psychosis spectrum hypothesis.
This candidate biomarker may help assess risk for psychosis-related disorders, inform diagnostic approaches, and guide treatment strategies. The researchers plan to review longitudinal studies to determine whether these white matter differences appear before or after the first symptoms, which would clarify whether they represent a vulnerability factor or a consequence of illness.
Published in: Nature Mental Health (2026)
