Genetics of Post-Traumatic Stress Disorder
In the wake of Hurricane Katrina, some residents of Louisiana, Mississippi, Alabama, and Florida are expected to suffer post-traumatic stress disorder (PTSD) and other stress-related disorders. The National Center for PTSD has extensive information on the emotional effects of natural disasters.
Some people, however, are clearly more susceptible to PTSD than others. While over 50% of U.S. women and 60% of men report having experienced a traumatic event at some point in their lives, only about 10% of women and 5% of men develop PTSD. In the August issue of the Psychiatric Times, Dr. Karestan C. Koenen, assistant professor in the department of society, human development, and health at the Harvard University School of Public Health, wrote about the genetics of of PTSD.
Up until the 1990’s, PTSD was believed to be rare in the general population – affecting only special groups, such as Vietnam War veterans. But recent studies have shown that PTSD most likely has a genetic component.
- Genetically distinct mouse strains reared in identical environments show variation in response to fear conditioning.
- In an earlier study of Cambodian refugees, children whose parents had PTSD were almost five times more likely to receive the diagnosis than children whose parents did not develop PTSD.
- Based on data from the Vietnam Era Twin Registry, which was created from the military records of male-male twin pairs who served in the Vietnam War, substantial genetic influences were also found on all PTSD symptoms, after adjusting for differences in combat exposure. There were similar findings in a non-veteran community sample of male and female twins
- Association studies of PTSD focusing on candidate genes involved in the dopaminergic system, which is one of the neurotransmitter systems involved in fear conditioning, found some evidence for the involvement of the D2 dopamine receptor gene (DRD2) and dopamine transporter gene SLC6A3.
- Gene expression profiles in peripheral blood mononuclear cells differentiated between individuals who developed PTSD and those who did not.
In the short term, identifying specific genes and figuring out how they work will make it possible to understand the neurobiological systems involved in PTSD and other related disorders.The hope is that genetic information can be used to develop predictive tests and better drug therapies.
Humans are amazingly resilient, bouncing back from traumatic and stressful events time and time again. Pain isn’t completely bad, though. As the Dalai Lama said,
[Pain] is a remarkable, elegant, and sophisticated biological system that warns us of damage to our body and thus protects us. …it is the feeling of unpleasantness that galvanizes and compels the entire organism to attend and act. It also sears the experience into the memory and serves to protect us in the future.
I definately believe PTSD is genetic, both sides of my family were it two diffenrent parts of the world during WWII. One side my great-grandparents and grandmother and the other side my grandmother. Both had PTSD now that I know what it is because I have it myself, so does my mother, of course they don’t know they had it. PTSD from that times period was more like a values system which included the American Dream and seeing everything in black and white. I’m the only one who realizes I have it and am trying to cope with it. But I think not only did they pas it along genetically but behaviourly, the fear, anxiety and paranoia all were part of my up bringing. There HAVE to be so many more people like me that are second generation Americans after WWII that grew up in the same way I did. I hope they are all well.