Smaller hippocampal volume in patients with recent-onset posttraumatic stress disorder

Background: Previous structural magnetic resonance (MR) research inpatients with posttraumatic stress disorder(PTSD) has found smaller hippocampal volumes in patients compared with control sublects. These studies have mostly involved sublects who have bad PTSD for a number of years, such as war veterans or adult survivor of childhood abuse. Patients with recent-onset PTSD have rarely been investigated. To our knowledge only one other study has investigated such a group. The aim of this study was to compare hippocampal volumes of patients with recent onset PTSD and nontrauma-exposed control sublects. Methods. Fifteen patients with PTSD, recruited from an accident and emergency department, were compared with 11, non-trauma-exposed, healthy control subjects. Patients underwent a structural MR scan soon after trauma (mean time = 158 +/- 41 days). Entire brain volumes, voxel size 1 X 1 X 1 mm, were acquired,for each subject. Point counting and stereology were used to measure the hippocampal and amygdala volume of each subject. Results: Right-sided hippocampal volume was significantly smaller in PTSD patients than control sublects after controlling for effects of whole brain volume and age. Neither left nor total hippocampal volume were significantly smaller in the PTSD group after correction. Whole brain volume was also found to be significantly smaller in patient. There were no difftrences in amygdala or white matter volumes between patients and control subjects. Conclusions. This result replicates previous findings of smaller hippocampal volumes in PTSD patients, but in an underinvestigated population, suggesting that either smaller hippocampal volume is a predisposing factor in the development of PTSD or that damage occurs within months of trauma, rather than a number of years. Either of these two h hypotheses have signficant implications for the treatment of PTSD. For instance, if it could be shown that screening for hippocampal volume may, in some cases, predict those likely to develop clinical PTSD.