What image comes to mind when we think of Post-Traumatic Stress Disorder (PTSD)? Most likely, we see an American soldier wearing his army greens incapable of escaping the sounds and images of the Vietnam War. Alain Brunet, PhD, of the Douglas Hospital Research Centre would argue however, that PTSD is not unique to soldiers. Thus, our mental images could also include traffic accident victims, fire fighters, police officers, paramedics, and crime victims (e.g. rape, sexual or physical abuse, assault, mugging, hold-up, child sexual abuse, etc.). For some, witnessing such occurrences could be sufficient for the development of the disorder.

Individuals living with PTSD typically have disturbing intrusive memories, flashbacks, and/or nightmares of the event. They are also likely to experience a sort of amnesia for aspects surrounding the event, show intense psychological distress and physiological reactions such as elevated heart rate and palpitations, sweating, and panic attacks when faced with situations resembling the trauma. As a result, these individuals often avoid any potential reminders of the event. Moreover, such symptoms frequently lead to impaired social or relational functioning, especially when the trauma involved humans hurting other humans.

After much research, Brunet has come to the conclusion that it is normal to display PTSD symptoms in the days and weeks after we experience a traumatic event. The difference is that in some individuals, these symptoms persist or become chronic.

To date, the study of PTSD has focused on why people develop the disorder retrospectively looking at long-term PTSD sufferers such as Vietnam War veterans or Holocaust survivors. This approach tells us very little about the vast majority of people: those who overcome their PTSD symptoms and go on with their life. In contrast, Brunet examines why and how people recover. He and his team follow trauma-exposed individuals (from the moment they are brought to the emergency room) over a period of one year in the hopes of identifying factors present before, during, and after a trauma that may foster recovery. 

Preventing the Development of PTSD

Brunet explains that PTSD is a disorder defined by a complex and dynamic interplay between psychological, environmental, hormonal, and neurobiological factors. Thus, in his research he examines each of these components. For instance, Brunet has developed an early intervention program aimed at preventing the development of PTSD in trauma-exposed individuals, an endeavor surely aided by his training as a clinical psychologist. His program has proven successful, which is in stark contrast with existing methods used in the prevention of PTSD. In fact, to date, in the PTSD scientific literature, Brunet’s psychosocial approach involving a specially trained nurse and one of the trauma survivor’s loved ones, has been unique in its ability to yield good clinical outcomes.

To address the more biological aspects of PTSD related to the recovery process, Brunet relies on the assessment of hormone levels, pharmacotherapy, and sophisticated neuroimaging techniques such as magnetic resonance imaging (MRI) that allow to look inside the brain.

The rationale for the use of such tools is related to the fact that, in the face of a traumatic event, we are endowed with a two-wave hormonal response designed to help us cope efficiently with a threat. The first wave of this response involves the rapid release of the hormone adrenaline. The second and slower wave depends upon the release of a stress hormone termed cortisol. Both hormones help prepare the body to either “fight or flee” the situation by causing things such as increased heart and respiratory rates and increased blood flow to our muscles. Another important role played by these hormones is that of helping us develop vivid memories of the situation, a cognitive ability that is thought to ensure species’ survival. It would surely have been important for our ancestors to remember events that led to a saber tooth tiger attack! In PTSD, it is possible that this adaptive enhancement of emotional memory becomes somewhat exaggerated such that trauma-related memories cannot be shut off.

In collaboration with a group of French researchers headed by Guillaume Vaiva, MD, PhD, Brunet set out to examine this question and administered a medication that blocks the function of adrenaline in trauma-exposed individuals in the 2-20 hours after they were brought to the emergency room. Their results showed that PTSD rates were higher in the group who did not take the medication after trauma exposure relative to those who received the medication.

What of the role of cortisol in PTSD? As previously mentioned, individuals with PTSD tend to experience memory loss or amnesia of certain aspects of the event. Cortisol is normally good for memory and for brain structures involved in memory processing like the hippocampus. Interestingly, one rather consistent set of findings in long-term PTSD sufferers is that of having a smaller hippocampus and having lower levels of cortisol. But, there are two schools of thought with regards to this issue. Are having a smaller hippocampus and low cortisol levels consequences of trauma-exposure, or do people who develop PTSD have a smaller hippocampus and lower cortisol levels to begin with? Brunet and his team may have helped shed some light on this issue. First, using their prospective approach of following trauma-exposed individuals in the hours after they arrive in emergency rooms, they have been able to show that 5 days and 4 months after trauma exposure, individuals who score high on PTSD scales already have lower levels of cortisol than do those who recover or who do not show PTSD symptoms. In fact, Brunet has shown that the low levels of cortisol found at the beginning of the study predicted whether or not a given individual developed chronic PTSD. Thus, his findings support to the view that low cortisol levels may in fact be pre-existing factors in PTSD sufferers rather than being the result of time-dependent damage.

Brunet and his team hope to find whether the same may be true with respect to the size of the hippocampus. Accordingly, through the use of MRI, they are following a group of trauma-exposed individuals over a period of one year and looking to see whether the size of the hippocampus changes over time. If the work of colleague Roger K. Pitman, MD, of the Harvard Medical School is of any indication, Brunet’s elegant studies will surely help disentangle a rather complex field.

Pitman is slated to give a conference at the Douglas Hospital Research Centre on June 10th 2004, at noon, and will discuss the findings of an elaborate study in Vietnam veterans. He examined identical twin brothers, one of whom served in Vietnam and the other who didn't. Among the veterans he studied, some suffer from chronic PTSD. Pitman found that Vietnam veterans with PTSD had a smaller hippocampus than did those without PTSD. Interestingly, so did their identical twin that had NOT been to Vietnam. In other words, given that we would expect identical twins to share similar physiology, it appears that the co-twin went to Vietnam with a smaller hippocampus in the first place.
Thus, a smaller hippocampus may indeed be a pre-existing factor in PTSD.

Through his innovative and multidisciplinary approach to the study of PTSD, Brunet, recent recipient of the 2004 Heinz Lehman Young Investigators Award, will surely help further our knowledge of the underpinnings of PTSD as well as significantly contribute to the development of new treatments for the disorder. Given our rising crime rates and that many of our armed forces personnel is being deployed to the Middle East, studies such as those performed by Pitman and Brunet will surely be welcome efforts.

By Tania Elaine Schramek