Link Between PTSD and TBI Is Only the Beginning for MRS Study

The longitudinal Marine Resiliency Study provides an important template for cooperation between the VA and Department of Defense and promises to shed new light on the impact of military service on health and well being.


April 25, 2014

A fundamental challenge for any study examining the impact of military service on the health of military personnel is establishing a baseline. Whether heart disease or posttraumatic stress disorder (PTSD), the symptoms often appear after (sometimes long after) the service has ended. The longitudinal Marine Resiliency Study (MRS I) and its successor MRS II are seeking to resolve that issue in a novel approach that brings together the Department of Veterans Affairs, U.S. Marine Corps, and Navy Medicine. 

In the MRS study, a cohort of about 2,600 Marines (MRS-I) in 4 battalions and about 1,300 Marines (MRS-II) in 2 battalions deployed to Iraq or Afghanistan underwent a scientifically rigorous examination a month prior to deployment. This baseline was established using self-reported questionnaires, clinical interviews, and laboratory examinations. Follow-up examinations were repeated at 3 months (MRS-I and MRS-II) and again at 6 months post-deployment (MRS-I).

The program is ambitious, Dr. Dewleen Baker of the VA San Diego Health Care System told Federal Practitioner. “MRS was designed to provide broad-based (psychosocial, psychophysiological, and biological) prospective, longitudinal data, with a goal toward ultimate integrated analyses of variables, to determine risk and resilience for post-deployment mental health outcomes, i.e,. PTSD and co-occurring disorders,” she explained. “Analyses have just begun, and we are working our way through aspects of the data toward more integrated approaches.”

In one of the first of many reports to come out of MRS, the researchers found that the probability of developing PTSD was highest for participants with severe pre-deployment symptoms, high combat intensity, and deployment-related traumatic brain injury (TBI). Most significant, the researchers found that TBI doubled or nearly doubled the PTSD rates for participants with less severe pre-deployment PTSD symptoms. According to Baker:

Based on evidence from previous studies, we anticipated that prior psychiatric symptoms and combat intensity would be important predictors of post-deployment PTSD symptom severity. In addition, previous work has suggested a strong association between symptoms of TBI and PTSD but without a causal link. These 3 factors were all significant predictors of post-deployment symptoms in our study. An individual with no preexisting PTSD symptoms and low combat intensity is at minimal risk for developing PTSD (less than 1% probability). Unit increases in preexisting symptom scores and combat intensity modestly increase post-deployment symptom scores by 1% to 2%.

By contrast, deployment-related mild TBI increases post-deployment symptom scores by 23%, and moderate-to-severe injuries increase scores by 71%. Our findings suggest that TBI may be a very important risk factor of PTSD, even when accounting for preexisting symptoms and combat intensity.

Our study focused on the impact of pre-deployment symptoms, combat intensity and TBI; however, it is important to consider other factors of psychological risk and resilience. Genes, coping style, and social support are just a few of the many other factors that may influence an individual’s response to stress.

Creating a rigorous cross-agency research study required tact, diligence, and patience from the MRS team. “Each agency has their own unique culture and institutional rules, regulations, and bureaucracy, so ideas, programs, etc, must be vetted across all agencies and reconciled—the various cultures/agencies to be reconciled include DoD, VA and academia.” Baker explained. “In addition in regards to initiation of studies for MRS II, for the past couple years, we also interface with NIMH as well as Headquarters Marine Corps; NIMH has the role of scientific review of MRS-II studies carried out under Headquarters Marine Corps/BUMED funding.”

The MRS-I and II studies may very well provide a template for future studies. The MRS team included a military liaison to work with the active duty Marines and attached Sailors, gather data, schedule meetings, and to report findings. “This study has a lot of experience working within and across these agencies,” Baker noted, “It’s an excellent model for future VA/DOD joint projects.”

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