Size of Brain’s Hippocampus Affects Response to PTSD Treatment

The size of a person's hippocampus, the part of the brain responsible for differentiating between safety and danger, is directly related to post-traumatic stress disorder (PTSD) and its treatment, according to researchers at Columbia University’s Mailman School of Public Health, Columbia University Medical Center, and the New York State Psychiatric Institute. While a smaller hippocampus has been linked to a higher risk for post-traumatic stress disorder, the latest study shows that a larger hippocampus increases the likelihood that treatment will have a positive effect. Findings are published online in the journal Psychiatry Research: Neuroimaging.

The study continues to strengthen theories that the hippocampus plays a large role in PTSD, including that size can indicate both severity of the condition and how effectively it can be treated, according to Yuval Neria, PhD, professor of Medical Psychology at the Mailman School of Public Health and director of the PTSD Program at the New York State Psychiatric Institute.

"If replicated, these findings have important implications for screening and treating patients who have been exposed to trauma," said Dr. Neria, who led this study, and is also a professor of Medical Psychology at Columbia University Department of Psychiatry. "For example, new recruits for military service may be scanned before an assignment to determine whether they are capable of dealing with the expected stress and trauma. Having a smaller hippocampus may be a contraindication for prolonged exposure to trauma."

For the study, researchers recruited 76 people -- 40 with PTSD and 36 trauma-exposed but healthy, resilient people -- to undergo clinical assessments and MRI, and then go through 10 weeks of prolonged exposure treatment. Among the participants, the healthy people and 23 PTSD patients who responded to treatment had larger hippocampal volume at the start of the study than the 17 PTSD patients who did not respond to the treatment.

While the researchers say the study supports ideas that hippocampal size is important both to the development of PTSD and response to treatment, more research is needed to confirm the connection and find more effective treatment. Future research may also help to determine if PTSD patients with a smaller hippocampus respond better to medication, either alone or in combination with psychotherapy.