Lesions that Cause Psychosis Map to a Common Brain Circuit in the Hippocampus

Identifying anatomy of circuits causally involved in psychosis could inform targeted treatments for schizophrenia. We identified 155 published case reports of brain lesions that caused new-onset psychosis. We mapped connectivity of these lesions using a normative human fMRI connectome. Lesions causing psychosis mapped to a common brain circuit defined by functional connectivity to the posterior subiculum of the hippocampus. A similar circuit was identified even when excluding lesions that touched the hippocampus. This circuit was consistent across individual symptoms of psychosis (delusions, hallucinations, and thought disorders). In an independent observational study (n=181), lesions connected to this circuit were preferentially associated with psychotic symptoms. A location in the rostromedial prefrontal cortex showing high connectivity to this psychosis circuit was identified as a potential target for transcranial magnetic stimulation. Based on these results, we conclude that lesions that cause psychosis have common functional connections to the posterior subiculum of the hippocampus.