Common Brain Circuit in Lesion-Induced Psychosis Suggests Stimulation Target
Lesions that cause psychosis affect a common functional brain circuit in the hippocampus, according to a study published in JAMA Psychiatry.
“These results can help inform therapeutic neuromodulation targeting,” wrote first author Andrew R. Pines, MD, MA, of Harvard Medical School, Boston, Massachusetts, and study coauthors.
READ>>Hippocampus May Be Epicenter of Psychosis Brain Change
The case-control study included 153 patients with lesions causing secondary psychosis and 1156 patients with lesions not associated with psychosis. Researchers mapped functional connections of published cases of lesion-induced psychosis compared with control lesions unassociated with psychosis. They were interested in whether lesion-induced psychosis was associated with a common circuit that could guide brain stimulation therapy for schizophrenia.
Among the 153 patients with lesion-induced psychosis, 82 were female, 71 were male, and 42 had psychosis described as schizophrenia or schizophrenia-like.
Lesions causing secondary psychosis affected a common brain circuit with functional connectivity to the posterior subiculum of the hippocampus (84% functional overlap), according to the study. At a 75% or greater overlap threshold, the circuit spanned the ventral tegmental area, retrosplenial cortex, lobule IX and dentate nucleus of the cerebellum, and the mediodorsal and midline nuclei of the thalamus.
“This functional circuit was consistent across different psychotic symptoms, suggesting a shared neural substrate for psychosis,” researchers wrote.
When investigators excluded 47 patients with lesions intersecting the hippocampus, the functional connectivity profile was similar, with the posterior subiculum at the center, signaling a circuit-level effect.
In an independent cohort of 181 patients with penetrating head trauma who underwent neurobehavior testing, lesions associated with psychosis symptoms including suspiciousness and unusual thought content demonstrated connectivity profiles that were significantly similar to the lesion-induced psychosis circuit.
“Voxels in the rostromedial prefrontal cortex are highly correlated with this psychosis circuit …,” researchers wrote, “suggesting the rostromedial prefrontal cortex as a promising transcranial magnetic stimulation target for psychosis.”
