Background. Magnetic resonance imaging (MRI) studies have especially reported smaller hippocampal volume in patients with post-traumatic stress disorder (PTSD), most of them war or sexual abuse victims. The present study compares the hippocampal volumes of out-patients with PTSD who had low co-morbidity rates to those of trauma-exposed control subjects without PTSD, and measures hippocampal volume changes in these patients after brief eclectic psychotherapy. We hypothesized that smaller hippocampal volumes are specific to PTSD and that hippocampal volume changes after effective psychotherapy would be measurable.

Method. Eighteen patients with PTSD and 14 traumatized control subjects were examined with MRI. In a randomized clinical trial, the PTSD patients were assigned to treatment (n=9) or waiting-list group (n=9). After the former received psychotherapy for 4 months, the MRI was repeated on both PTSD groups. Three temporal lobe structures were manually segmented: hippocampus, amygdala, and parahippocampal gyrus. Volumetric analysis was used to measure grey matter, white matter, and cerebrospinal fluid.

Results. PTSD patients had significantly smaller hippocampal volumes at baseline (total 13·8%, right 13·5%, left 14·1%) compared to the control subjects. After effective psychotherapy, however, no volume changes were found in the smaller hippocampi.

Conclusions. We confirmed previous findings of smaller hippocampal volume in PTSD in a new population made up of out-patients who experienced different types of traumas, reducing co-morbidity to a minimum. Smaller hippocampal volumes did not change after effective psychotherapy, even while symptoms resolved.