The National Vietnam Veterans Longitudinal Study (NVVLS) and the implications for the science and practice of PTSD: An interview with Dr. Charles Marmar

soldier-294476_640The National Vietnam Veterans Readjustment Study (NVVRS) was conducted in 1983 as a response to a congressional mandate for an investigation of PTSD and other postwar psychological problems among Vietnam veterans. More than 25 years after the original NVVRS study was conducted, researchers reassessed more than two thousand of the original study participants for symptoms of PTSD. What made this research unique was that the long-term course of PTSD in military personnel had not previously been evaluated in a nationally representative sample. This follow up study, called the National Vietnam Veterans Longitudinal Study (NVVLS), found a current prevalence of PTSD in 4.5% of male and 6.1% of female combat Vietnam era veterans. Extrapolating these figures suggests that more than a quarter of a million Vietnam veterans still struggle every day with the consequences of PTSD forty years after that war ended.

The study was led by Charles R. Marmar, MD, the Lucius N. Littauer Professor  and chair of the department of Psychiatry at NYU Langone Medical Center and director of its Steven and Alexandra Cohen Veterans Center, a leading program in the study of PTSD. A pioneer in the field of PTSD research, his work has led to breakthroughs in our understanding of PTSD through the study of police officers, soldiers in combat, veterans, and civilians who have been exposed to sudden, usually life-threatening, events.

Recently, I spoke to Dr. Marmar about the implications of the NVVLS study and about his 40 year career as a PTSD researcher.

Dr. Jain: For my first question, can you start by commenting on the large percentage of Vietnam veterans you and your team studied that has never suffered from PTSD linked to war? I feel sometimes that percentage gets lost in some of the headlines and media coverage of PTSD research.

Dr. Marmar: Yes. It is a little difficult to give a precise overall estimate, but if you look across our data from both the first wave of our study (collected between ’84 and ’88) and then the second wave (collected between 2011 and 2013), it is roughly a 75% and 25% split. Of course it depends precisely on how you define PTSD, and that has changed over the years, but you could say that approximately 3/4 of Vietnam veterans who served in the warzone never developed significant levels of stress, anxiety, or depression related to their military service. They were relatively resilient. Now, that is only an average across all 3.1 million men and women who served. There is a lot of variability depending on who you were, how old you were, how many times you were deployed, and what your service duties entailed. In a warzone deployment, there are three broad roles: combat, combat support, and service support. All three roles come under the definition of a warzone, but the number of people who are actually repeatedly at the tip of the sword is a smaller percentage, and that factors in to the individual risk calculation.

Dr. Jain: Yes. Actually as you talk, something comes into my mind about recent returnees from the conflicts in Afghanistan and Iraq. Military rank appears crucial. Lower ranking military members are exposed to higher doses of trauma and are therefore more vulnerable. Is that something that you looked at in the Vietnam study or is that something you can offer some feedback on?

Dr. Marmar: In general, older, more educated war fighters of higher rank are able to tolerate the intensity of combat and are more resilient. Also, as you indicated, in general, their levels of repeated combat exposure are lower if they were squad leaders rather than squad members.

Dr. Jain: Dr. Hoge’s editorial that accompanied the article described your research as “methodologically superb.” Can you comment a little bit from a researcher’s perspective on the strength of your study and how it is different to previous efforts to document the prevalence or course of PTSD in this population?

Dr. Marmar: Firstly, we believe it is the only study in the world (with the possible exception of studies conducted by Solomon et al with the Israeli Defense Force) which followed, in an epidemiologically sound way, a representative sample of every man and every woman who served in a major conflict. The study was not done by recruiting people from VA hospitals and clinics or by advertising on Craig’s list, etc. So it takes into account the differences between community samples and VA seeking patients, as these are two very different groups. This study was drawn top down from military records. It included people from all 50 states, Guam, and Puerto Rico, and it included urban, suburban, rural, and extremely remote veterans. So, for example, we have included participants from the remote aspects of the Big Island of Hawaii, all the way to Manhattan. It is a truly representative sample in this regard. Secondly, we oversampled for women and minorities. This gave us more statistical power to look at these populations too. Thirdly, the study is exceptionally successful in its implementation. We had zero contact with our cohort for 25 years. We never contacted a single one of them on a single occasion and still retained just under 80% of them for the follow up 25 years later. The study has many excellent features, but the most important features are that it has true representational sampling, over representation of women and minorities, and its high retention rate over 25 years.

Dr. Jain: That’s what makes it a very important piece of science in our understanding of the prevalence and course of PTSD.

Dr. Marmar: It also tells you something profound about the participants’ commitment to the research. Another thing is it is very deep, because we have up to 5-hour household interviews, survey interviews, and 3-hour clinical interviews on a sub-sample. For this follow up study, we had a 1-hour self-report package, 1 to 2-hour interview by professional survey interviewers, and 3 to 5-hour clinical interviews done by my team at NYU. We used a team of highly qualified PhD clinical interviewers, and they were able to interview people by telephone so that we could sample, in the clinical interview, people from all over the country. It is very hard to do that if you ask participants to come into regional medical centers.

Dr. Jain: Can you talk a little bit about sub threshold (or partial) PTSD? Clinicians see that all the time—patients who might not meet the diagnostic criteria, but that does not mean they do not have symptoms that have a significant impact on their quality of life. Sub threshold (partial) PTSD is something I believe you chose to measure in the study. Can you tell us a little bit about your findings?

2012-04-05-ptsd1Dr. Marmar: What we do know is that roughly as many Vietnam veterans have partial PTSD today as have full PTSD. We define partial PTSD very strictly. We had a very well-defined algorithm of what constitutes partial PTSD. The important things to note are that the overall symptom levels are relatively high in the partial group, and their functioning difficulties in work and love are also high. In fact in our work, and in some prior publications, the levels of dysfunction are quite similar in people with partial and full PTSD. Levels of medical comorbidity may be quite similar, too. So partial PTSD is very important. The other thing we found is that roughly 5% of the Vietnam veterans alive today, who served in the war, meet full criteria for PTSD, but an equal number meet partial criteria. We also found that roughly 1/3 of Vietnam combat veterans with PTSD today also have full current comorbid major depressive disorder. That is almost identical to the rate of comorbid major depression that we found in the partial group. You can see that there is a heavy burden of symptoms, comorbidities, and dysfunction in the partial group. A big study about partial PTSD, published in 2001 in the American Journal of Psychiatry, reported similar findings.

Dr. Jain: From your findings it is definitely something we need to be more aware of and on the lookout for to make sure these patients are also getting services where indicated or having their symptoms addressed.

Dr. Marmar: Absolutely. I think this is an important and potentially underserved group. They probably function a little better, maybe overall, than those with the full, more severe form, but there is still a heavy burden of illness. We have statistical models which examine the extent to which full PTSD is a risk factor for medical comorbidity and premature death. An important follow up question would be: Does carrying a diagnosis of chronic partial PTSD over years to decades shorten your life? I think physicians should be very concerned about the physical and medical problems of veterans with partial PTSD: cardiovascular risk, stroke risk, metabolic load, diabetes, and cancer.

Dr. Jain: Right. Yes. There is this whole other body of literature that is emerging that really fleshes out this sensitive relationship between PTSD and physical illness.

Dr. Marmar: In a study we did that was published in JAMA in 2009, my colleague Beth Cohen and I downloaded the VA national database and looked at 250,000 OEF/OIF veterans enrolled in VA healthcare nationally. We asked a simple question: If you compare veterans with no current mental health diagnosis, what do these medical risk factors look like in those with PTSD alone, depression alone, and comorbid PTSD and depression? At that time, around 2009, we had these pretty young, recently returning Iraq and Afghanistan veterans, and we found huge, two to three times increases in levels of dyslipidemia, type 2 diabetes, obesity, and other problems in those with psychiatric illness.

Dr. Jain: One of the wonderful things about working in the VA is that, as a system, it cares about PTSD. It funds not only clinical programs, but many research efforts too. In addition to that, there is political and societal motivation to support the funding of studies such as yours. As a physician, I am well aware that PTSD is not just an issue for veterans. It is an issue across our culture, across our society. It is an issue globally. Because so much cutting edge research on PTSD is done in veteran populations, it can contribute to a societal myth that PTSD is only a veteran issue. Your study offers a much needed contribution to advancing the science of PTSD, but it raises another question in my mind: Would the results be that different in a civilian population?

Dr. Marmar: It is difficult to say. War fighters are repeatedly exposed to personal life threat. It is somewhat less common in a civilian world. War fighters not only had their own life in danger, but they are required, by their service to their country, to take the lives of other people. This adds a different dimension to trauma than say, being a sexual assault survivor (which, of course, is horrible), or a vehicle accident or national disaster survivor. Killing is different than just having your life in danger. This has been written about more recently as the “moral injury” of war. In general, clinically, I think you would agree that there are easier cases that are more easily treated, and more difficult cases that are more difficult to treat. That is true in every aspect of the practice of medicine. In trauma, people who are repeatedly exposed to trauma early in life and who perpetuate violent acts, as part of the trauma experience, actually are different, and they have a different form of PTSD that is more complex, more chronic, and, generally, more treatment refractory.

Dr. Jain: Jonathan Shay wrote about the specific plight of Vietnam veterans in his 1994 book, Achilles in Vietnam: “such unhealed PTSD can devastate life and incapacitate its victims from participation in the domestic, economic, and political life of the nation. The painful paradox is that fighting for one’s country can render one unfit to be its citizen.” Shay’s anecdotal observations seem prophetic when considered in the light of your recent study. Can you comment about what your research showed about the quality of life of Vietnam veterans who still have combat related PTSD?

Dr. Marmar: I would say the effect on quality of life is very profound. Think, by analogy, about the study of the effects of psychotic symptoms among patients with the schizophrenia spectrum disorders. As you know, early on when the concept of schizophrenia was being developed, the focus initially was on the rather dramatic positive symptoms: delusions, hallucinations, the jumbled thinking, and so on. But actually as you begin to analyze what is related to functional disability, it is often more the negative symptoms of schizophrenia: the amotivational syndrome, apathy, detachment, dysphoria, and depression. I would say, in some ways, that is true for PTSD. The nightmares and flashback, the startle reactions—these positive symptoms are very disturbing. But the negative symptoms, which include numbing, detachment, inability to express and receive affection, erosion of the ability to enjoy things, and so on—those negative symptoms are very devastating to function. They often lead to withdrawal, fractured family, and alienation, and they are often associated with heavy alcohol and drug misuse. The negative symptoms are very important.

Dr. Jain: Right. That has a knock-on effect on capacity to work, capacity to parent, and capacity to engage in social relationships. In that way, I think it really speaks to how PTSD as a disease entity that goes beyond the individual human and their own biology and really extends and infiltrates our society.

Dr. Marmar: Yes. Very very much so. I mean, for every war fighter who is traumatized, there are 10 to 20 people in their lives that are part of their social fabric that are affected to varying degrees: parents, siblings, spouses, children, grandchildren. That is a huge network. They are all affected.

Dr. Jain: Again, coming back to your JAMA study, I feel like someone who is thinking both from the perspective as a clinician and researcher. I think intuitively, a lot of clinicians have been seeing this type of picture for decades, but what is validating is to have an excellent, well-designed, very rigorous scientific study which gives us that support for what we have been seeing on the ground. In my understanding, that is what your study has done. Can I ask how many years you been doing PTSD work?

Dr. Marmar: I have more than 40 years of experience as a trauma clinician and researcher. In a way, my professional history parallels that 40-year Vietnam study. I am probably more energized and passionate about my trauma research today than when I started 40 years ago.

Dr. Jain: Why do you think that is?

Dr. Marmar: It took a long time to really grasp the depth of what this subject was really about. We did not have all the tools. We did not have the sophisticated epidemiological studies. We did not have advances in translational neuroscience to probe the neurocircuitry, neuroendocrinology, or the neurogenetics for the illness of PTSD. I am very excited that the world is captivated by PTSD, and we have the tools now to make very dramatic advances, for example, to develop panels of blood and brain imaging biomarkers that would definitively say who does not have PTSD, who has partial PTSD, who has regular PTSD, etc. We will crack that code in your academic lifetime. It is an exceptionally rich and open field, and there is an opportunity to make huge contributions.

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