PTSD Risk May Be Inherited, Study Finds
Posttraumatic stress disorder (PTSD) has been in the news a lot in the past few years, especially regarding its prevalence among military personnel returning from Afghanistan and Iraq. Now, based on gene research, scientists report that PTSD risk may be inherited, information that could be important for soldiers and others at risk for PTSD.
Could we screen for PTSD?
PTSD is an anxiety disorder in which individuals who have experienced a dangerous event continue to feel stressed or traumatized even when they are no longer in danger. Symptoms can be far-ranging and life-altering, and fall into three general categories:
- Re-experiencing symptoms (e.g., flashbacks, bad dreams)
- Avoidance symptoms (staying away from places or events that remind them of the experience, feeling guilt or depression, feeling emotionally numb),
- Hyperarousal symptoms (e.g., being easily startled, experiencing sleep difficulties, feeling tense all the time)
Researchers at the University of California, Los Angeles (UCLA) linked two genes that are involved with the production of serotonin to having a greater risk of developing PTSD. Serotonin is a brain chemical intimately involved with mood, sleep, and alertness.
The investigators made their discovery while studying the DNA of 200 adults from several generations of 12 extended families who experienced symptoms of PTSD related to the 1988 earthquake in Armenia.
The research team, under direction of Dr. Armen Goenjian, a research professor of psychiatry at the Semel Institute for Neuroscience and Human Behavior at UCLA, found that individuals who had specific variants of two genes—TPH1 and TPH2--were more likely to develop PTSD symptoms. Both of these genes control the production of serotonin.
Goenjian noted that if their findings are confirmed, they “could eventually lead to new ways to screen people at risk for PTSD and target specific medicines for preventing and treating the disorder.” The potential for using this information for PTSD screening alone is significant.
PTSD in the military
If such a screening tool was developed, it “could enable military leaders to identify soldiers who are at higher risk of developing PTSD, and reassign their combat duties accordingly,” noted Goenjian.
PTSD among military personnel is a significant problem. In a study published in the Archives of General Psychiatry, for example, mental health surveys collected from 18,305 US Army soldiers found a prevalence of PTSD ranging from 20.7% to 30.5% when the least stringent definition of PTSD was used.
Even when a stricter definition of PTSD was used, prevalence of PTSD was 5.6% to 11.3%. About half of the affected soldiers also displayed aggressive behavior or alcohol misuse.
In a Rand Corporation study, it was reported that 20% of service personnel who served in Iraq or Afghanistan had symptoms of PTSD. Another study noted that the risk of dementia is higher among veterans with PTSD than among those without PTSD.
The discovery of the two gene variants that may be associated with PTSD will help researchers classify the disorder based on brain biology rather than on clinical observation, noted Goenjian. Hopefully it will also lead the way to new treatments for PTSD.
Qureshi SU et al. Greater prevalence and incidence of dementia in older veterans with posttraumatic stress disorder. Journal of the American Geriatrics Society 2010 Sept; 58(9): 1627-33
Rand Corporation. “One in five Iraq and Afghanistan veterans suffer from PTSD or major depression.”
Thomas JL et al. Prevalence of mental health problems and functional impairment among active component and National Guard soldiers 3 and 12 months following combat in Iraq. Archives of General Psychiatry 2010; 67(6): 614-23
UCLA Health System
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