Reality Is in the Posterior Hippocampus: Who Knew?

Abstract

Bilateral Volume Reduction in Posterior Hippocampus in Psychosis of Epilepsy Allebone J, Kanaan R, Maller J, et al. J Neurol Neurosurg Psychiatry. 2019. pii: jnnp-2018-319396. doi:10.1136/jnnp-2018-319396. [Epub ahead of print]. PMID: 30796132. Objective: Psychosis of epilepsy (POE) occurs more frequently in temporal lobe epilepsy, raising the question as to whether abnormalities of the hippocampus are etiologically important. Despite decades of investigation, it is unclear whether hippocampal volume is reduced in POE, perhaps due to small sample sizes and methodological limitations of past research. Methods: In this study, we examined the volume of the total hippocampus, and the hippocampal head, body, and tail, in a large cohort of patients with POE and patients with epilepsy without psychosis (EC). One hundred adults participated: 50 with POE and 50 EC. Total and subregional hippocampal volumes were manually traced and compared between (1) POE and EC; (2) POE with temporal lobe epilepsy, extratemporal lobe epilepsy, and generalized epilepsy; and (3) patients with POE with postictal psychosis (PIP) and interictal psychosis (IP). Results: Compared to EC, the POE group had smaller total left hippocampus volume (13.5% decrease, P