Brain Sulcal Asymmetry Declines Stepwise with More Frequent Voice-Hearing in Schizophrenia

Schizophrenia spectrum patients who hear voices more often show progressively less asymmetry in two folds of the frontotemporal brain surface, according to a new study of the paracingulate sulcus and superior temporal sulcus.

Researchers measured the length of the paracingulate sulcus and the depth of the superior temporal sulcus in patients stratified by how frequently they experienced auditory verbal hallucinations. Rather than dividing patients into a simple hallucinating versus non-hallucinating group, the team ordered participants by the frequency of voice-hearing, allowing them to test whether the brain asymmetry changed in a graded, stepwise fashion across the clinical spectrum.

The analysis revealed an ordinal reduction in sulcal asymmetry as hallucination frequency increased, meaning that the more often patients reported hearing voices, the less asymmetric these structures appeared. This pattern reached statistical significance only for the depth of the superior temporal sulcus. The paracingulate sulcus showed a similar directional trend, but the graded reduction did not reach statistical significance for its length.

The authors suggest that the decline in effect size from frequent to less frequent hallucinations may explain why earlier studies, which typically used binary classifications of hallucination status, produced inconsistent findings. By collapsing patients with very different levels of voice-hearing into a single category, such approaches disregard clinical heterogeneity and may dilute or obscure the underlying relationship between brain structure and symptom severity.

The findings, published in the journal Schizophrenia, add to evidence linking structural asymmetries of frontotemporal cortical folds to the severity of auditory verbal hallucinations. The authors note that the version released is subject to further edits before the final version of record.

Subject of Research: The relationship between frontotemporal sulcal asymmetry and the frequency of auditory verbal hallucinations in schizophrenia spectrum disorders

Article Title: Ordinal reduction of frontotemporal sulcal asymmetry with increasing auditory verbal hallucinations in schizophrenia spectrum disorders

Article References: Wu, S.-C. J., de Vareilles, H., Salgado-Pineda, P., Barbosa, L., Soler-Vidal, J., Fuentes-Claramonte, P., del Olmo-Encabo, P., Inarejos-Clemente, E., Hoyos, B., Ramiro, N., Ruiz, J., Boatas, F., Suckling, J., Pomarol-Clotet, E., McKenna, P. J., & Murray, G. K. (2026). Ordinal reduction of frontotemporal sulcal asymmetry with increasing auditory verbal hallucinations in schizophrenia spectrum disorders. Schizophrenia. https://doi.org/10.1038/s41537-026-00821-3

Image Credits: AI Generated

DOI: 10.1038/s41537-026-00821-3

Keywords: schizophrenia, auditory verbal hallucinations, paracingulate sulcus, superior temporal sulcus, brain asymmetry, sulcal anatomy, neuroanatomy, psychosis, frontotemporal cortex, clinical heterogeneity, Ordinal, reduction