Association Between Unremitting PTSD and Smaller Right Hippocampal Volume Among Veterans 30 Years After Combat

A significant percentage of individuals diagnosed as having posttraumatic stress disorder (PTSD) show remission within the first year after traumatic exposure, with more gradual improvement over the next several years. However, a subgroup of individuals with PTSD have an unremitting course of illness that may persist for years or decades despite treatment efforts. The authors tested the hypothesis that reduced hippocampal volume is associated with chronic, unremitting PTSD rather than with PTSD that has remitted over time.

The study included 44 Vietnam War veterans whose traumatic exposure had occurred more than three decades before study participation. The authors studied the association between hippocampal volume and three PTSD diagnostic categories: veterans with unremitting PTSD (N=26), veterans with sustained remission from earlier PTSD (N=8), and veterans who never developed PTSD (N=10).

Compared with trauma-exposed veterans who never developed PTSD, those with unremitting PTSD, but not those who had recovered, showed reduced hippocampal volume. The results were anatomically lateralized to the right hippocampus, consistent with previous neuroimaging studies of male combat veterans.

These results support an emerging literature suggesting that reduced hippocampal volume observed among individuals with PTSD may be related to failure to recover from rather than to the development of PTSD after trauma exposure. These findings may define a subpopulation of combat veterans who are at increased risk for long-term failure to recover from PTSD because of their smaller right hippocampi.