Hyperactivity of the anterior hippocampus impairs task-related recruitment in patients with early psychosis, according to a recent article in The American Journal of Psychiatry.
The study authors aimed to determine how activation of the hippocampus relates to impaired recruitment during scene processing. They compared 100 individuals (45 patients; 35 matched healthy controls) from an ongoing longitudinal functional magnetic resonance imaging (MRI) study of the early stages of psychosis. Most patients were in their initial months of illness. Of the initial 100 individuals, 20 were excluded due to poor data quality or technical issues. Baseline hippocampal activity was measured using cerebral blood volume (CBV) in a subset of the participants (20 patients; 31 healthy controls).
Patients in the early stages of psychosis showed significantly reduced activation of the hippocampus due to elevated baseline function when compared with the healthy control group (P =.003). There was an increase in CBV in the anterior hippocampus in patients with early psychosis compared with healthy control individuals (P =.006). The authors observed strong evidence of a negative correlation between high baseline activity and low task activation of the anterior hippocampus in the patients in the early stages of psychosis (r=-0.50; P =.01). This observation was not present in the healthy control group (r=0.16; P =.81).
Limitations of this study include the small number of patients for which both functional MRI and CBV data were available. Furthermore, CBV imaging presents several challenges to obtaining a larger group of patients, including lack of participation due to its invasive nature and weight and kidney function requirements.
The authors concluded that “using a multimodal imaging approach, we found novel evidence for anterior hippocampal dysfunction in early psychosis. Longitudinal studies are needed to examine the relationship between the observed functional differences and subsequent structural changes in the hippocampus and outcomes of patients with psychosis.”
McHugo M, Talati P, Armstrong, K, et al. Hyperactivity and reduced activation of anterior hippocampus in early psychosis [published online October 18, 2019]. Am J Psychiatry. doi: 10.1176/appi.ajp.2019.19020151