Smaller hippocampal volume following sexual assault in women is associated with post-traumatic stress disorder

Objective: Exposure to sexual assault is a significant risk factor to develop post-traumatic stress disorder (PTSD) in females. The early neurobiological changes leading to the development of PTSD remain understudied and unclear in this population. Methods: Participants were 27 adult females recruited within a month following exposure to sexual assault (T1) and 20 age-matched non-exposed controls. Among the victims, 10 participants met (PTSD+) and 15 did not meet (PTSD-) DSM-IV criteria for PTSD 6 months post-trauma (T2). At both visits, hippocampal and amygdala volumes were extracted from magnetic resonance imaging scans, and indices of total diurnal cortisol changes were derived from individual areas under the curve relative to the ground (AUCg). Measures at T1 were compared between groups at T1, measures at T2 between groups at T2, and measures at T1 between groups at T2. Results: At T1, victims had significantly smaller bilateral hippocampal volumes, but not AUCg, than controls. At T2, neither hippocampal volume nor AUCg significantly differed among the groups. However, the PTSD+ group had significantly smaller hippocampal volumes at T1 than the control group, but not compared to the PTSD- group. Conclusions: This study indicates that having smaller hippocampal volumes is a risk factor to develop PTSD in females exposed to sexual assault.