The 2,233rd Meeting of the Society

February 8, 2008 at 8:00 PM

Powell Auditorium at the Cosmos Club

Epidemiology of PTSD and Mild Traumatic Brain Injuries among Soldiers Returning from Iraq

Charles Hoge

US Army Medical Corps
Walter Reed Army Institute of Research

About the Lecture

Previous studies of the mental health effects of combat have generally been conducted years (or even decades) after service members returned home. The current war in Iraq and Afghanistan is unique in the amount of research that has been conducted on the mental health effects of combat as the war has been ongoing, to include population-based health services research. Various studies have shown that up to one-third of service members in ground combat units experience significant symptoms of post-traumatic stress disorder (PTSD), depression, anxiety, alcohol misuse, or family problems resulting in referral for mental health treatment. The ongoing research has led directly to new population-based health care policies to include post-deployment mental health assessments, program evaluation, and new efforts to reduce stigma. However, despite these efforts, over half of service members with serious mental health concerns do not receive treatment, and stigma remains pervasive. In addition, there has been increasing concern about mild traumatic brain injuries related to exposure to blast explosions, and the overlap between mild TBI and PTSD. This talk will discuss the lessons learned about PTSD and mild TBI among Iraq and Afghanistan war veterans from an epidemiological perspective, to include discussion of current issues and controversies.

About the Speaker

CHARLES W. HOGE is a Colonel in the U.S. Army Medical Corps. He originally trained in internal medicine and infectious diseases. From 1989-1991, he served in the U.S. Public Health Service as an EIS (Epidemiology Intelligence Service) officer at Centers for Disease Control, where he learned epidemiology and led several infectious disease outbreak investigations. He switched from USPHS to the Army in 1991, and spent the next six years, including four years in Thailand, conducting numerous field studies related to the treatment and prevention of tropical infections that affect U.S. soldiers deployed to developing countries. In 1997, he had a career change to psychiatry and completed his residency in psychiatry at Walter Reed Army Medical Center in 2000. For the last seven years COL Hoge has led a psychiatric research program at Walter Reed Army Institute of Research (WRAIR) focused on mitigating the mental health impact of the current wars in Iraq and Afghanistan. He has over 70 peer-reviewed publications, including lead articles on his current research in JAMA (March 2006 and November 2007) and New England Journal of Medicine (July 2004).


President Kenneth Haapala called the 2,233rd meeting to order at 8:21 pm February 8, 2008 in the Powell Auditorium of the Cosmos Club. The minutes of the 2,232nd meeting were read and approved.

Mr. Haapala introduced the speaker of the evening, Mr. Charles W. Hoge, who spoke on the topic, “Epidemiology of PTSD and Mild Traumatic Brain Injury (mTBI) among Soldiers Returning from Iraq.” Mr. Hoge leads a psychiatric research program at Walter Reed Army Institute of Research focused on mitigating the mental health impact of the wars in Iraq and Afghanistan.

Mr. Hoge said he would deal first with the epidemiology and then mild traumatic brain injury. This latter term, he said, is an oxymoron — brain injury is never mild.

What the “health” is epidemiology, Mr. Hoge asked. It is the study of the distribution and determinants of diseases in specified populations.

He reviewed the basic principles in epidemiology used to infer causation, which Mr. Haapala had also mentioned in introducing Mr. Hoge. These principles were expressed in 1965 by Austin Hill in the course of his debates with Ronald Fisher about the effect of smoking on lung cancer. These principles are:

Strength of the relationship
Consistency of observation
Logical time sequence, the inferred effect following the inferred cause.
Dose response, increased exposure associated with increased risk.
Biological plausibility.
Coherence, association consistent with natural history.
Analogy (similar associations with other diseases).
Experimental evidence (intervention helps).
PTSD (post-traumatic stress disorder) “came into existence,” he said, in the early 80's, when the disease was observed among Viet Nam veterans. The disease is caused by a traumatic event involving threatened or actual death or serious injury to self or others and presents as a response of intense fear, helplessness, or horror. The symptoms are severe or interfere with functioning. They may include nightmares, flashbacks, and int rusive memories, difficulty sleeping, concentration problems, emotional detachment, and others.

The disease is strongly associated with trauma although only about 30% of soldiers most exposed to trauma develop the symptoms. It is found in multiple populations. It only follows, never precedes, trauma and is related to both the severity and frequency of trauma. Being wounded in combat is followed by PTSD more than twice as often as combat without being wounded. Interventions, both drug and behavioral therapy, do relieve symptoms somewhat.

There has been considerable work since the start of the war on the availability of help for affected soldiers. Stigma has been a major concern because it often prevents treatment. Despite the efforts, stigma remains pervasive. Effort now goes to better educating leaders, family members, and medical personnel regarding psychological health. Nevertheless, 50 - 65% of soldiers strongly agree that accepting mental health care would cause them to be seen as weak, cause their leaders to treat them differently, harm their careers, and the like.

He showed a diagram of a human brain showing that the limbic system, sometimes called the reptilian brain, is a center for survival related emotions and responses, fear, rage, flight, and fight. He showed a series of pictures taken in Iraq that illustrated plenty of reasons for stress and trauma.

Alcohol overuse and abuse increase substantially after deployment, as does physical aggression. A number of other measures of poor health also relate to PTSD. He noted that passing out with alcohol is not actually sleep; it has a very different architecture, so alcohol may be aggravating the problem.

Someone asked if anything in the limbic system predicts who develops PTSD. No, Mr. Hoge said, but we do know that those who have had traumatic experiences as children do have higher risk. Even the first sergeants and staff sergeants cannot predict who will get it.

Then he turned to the “signature” disorder of this war, mild traumatic brain injury. mTBI is a loss of consciousness of 30 minutes or less or transient memory loss. Unconscious of more than 30 minutes is called moderate traumatic brain injury. At 30 minutes, you can see the pathology in brain. With mild TBI, you can’t see it. There is no relationship of the symptomology with the injury. In mild TBI, the axons are twisted or pulled, but not sheared. These definitions are not tight. They depend on self-reports, and the self reporters don’t seem confident of their reports.

Some victims go back to normal and some don’t. They continue to have headaches, difficulty concentrating, and related symptoms. Indications are that these are generalized injury responses.

The only effective treatment for mTBI is information to normalize the victim’s behavior. Convincing them they will get better leads them to get better.

Finally he said that none of the standards for causative inference are met by mTBI.

During the question - answer session, someone asked about football injuries and PTSD. Football injuries do not lead to PTSD, but car accidents do. In this context, he said that litigation is the strongest indicator of mTBI symptoms.

He was asked, “Is there any way of predicting the magnitude of the problem when this war is over?” He responded that the hope is that, since we have better treatment and more victims are getting in earlier for treatment, it will be moderate.

“What has been done to mitigate the effect of stigma?” he was asked. Mental health care has been increased and mental health screening has been increased. Also, soldiers are being taught that they have to be tactically aware while in combat, but at home that will be a symptom.

“Why was PTSD not reported in earlier wars?” Actually, something was reported after all wars. “Shell shock” and terms like it were used for the syndrome.

After the address, Mr Haapala presented to Mr. Hoge a commemorative plaque and welcomed Mr. Hoge to membership in the Society. He exacted a princely sum from nonmembers of the Cosmos Club who parked in the Club lots and referred these people to the Society’s new treasurer, Boris Comiceau. He made a pitch for support. He directed folks considering membership to Bob Hershey, who wielded his trusty trifold brochure. He announced the next meeting. Finally, at 9:45 pm, he adjourned the 2233rd meeting to the social hour.

Attendance: 76
The weather: Calm
The temperature: 6°C
Respectfully submitted,

Ronald O. Hietala,
Recording secretary