Double Duty: Psychology Graduate Student Hopes Twins Hold Key to Understanding Post-Traumatic Stress Disorder

On most days, Michael VanElzakker can't help but see double.

This is what happens when your research subjects are twins.

VanElzakker, a GSAS psychology doctoral student and member of Professor Lisa Shin's research group, is studying post-traumatic stress disorder (PTSD) among identical twins, many of whom fought in the Vietnam War. PTSD—which afflicts as many as 14 percent of returning Iraq War veterans (Source:" PTSD And Depression Common In Returning Combat Soldiers," National Public Radio, 2010)—is characterized by reoccurring memories of an emotionally traumatic event. A person with PTSD may experience flashbacks of the traumatic event; have uncontrollable, negative thoughts; avoid places or things associated with the traumatic experience; and/or have difficulty controlling emotions.

VanElzakker's research focuses on the possibility of a biological link to PTSD, that the neural wiring of certain individuals may make them a more likely candidate to be afflicted with the disorder.

The twins in VanElzakker's study are broken up into two groups. The first group consists of twins who fought in the Vietnam War and got PTSD (their fellow twin was not involved in the conflict). The second group consists of twins who fought in the Vietnam War and did not get PTSD; like with the first group, the fellow twin did not fight.

"We fly the twins in from all over the country for two long days of brain scans and other types of testing," said VanElzakker. "We collect a lot of information about the structure and function of our participants' brains. For example, we look at the chemical composition of their brains, the shape and size of certain structures, and the thickness of nerve fibers within the brain. We also look at how the brain responds functionally to different types of emotional and cognitive experiences."

To gauge how the brain functions in the face of these experiences, VanElzakker and his fellow researchers expose test subjects in the lab to a series of "fearful" and "non-fearful" faces.

When someone sees a "fearful face" or image, it can trigger a response in the amygdala, the part of the brain which alerts an individual of a threat; it also appears that this part of the brain stores emotional memories which can "hold" a person's fear of, for example, spiders or dogs.

Even though VanElzakker's project is in its early stages, there have been some interesting developments thus far.

"The data are still being collected, and so all analyses are still quite preliminary," said VanElzakker. "But from what the data look like so far, one of the most striking things is that there really seems to be a pre-existing neurocircuitry vulnerability to PTSD."

In other words, it appears that the twins in the study may be predisposed to developing PTSD.

"The circuits involved in fear memory look very similar in the veterans with PTSD and their twins," said VanElzakker. "We hypothesized that the brains of veterans with PTSD would be unique. But it's more like PTSD takes root in circuits that were already there. We're hoping to find ‘biomarkers,' meaning that we want to understand what PTSD looks like in the brain and body. This information should result in more effective and perhaps more personalized treatment strategies. Hopefully, the twin study will help us better understand the root cause of those biomarkers."