According to a new UCLA study, two gene variants to post-traumatic stress disorder (PTSD) affect an individual’s risk of developing the condition. The findings could lead to more effective methods to diagnose and treat the disorder.
“Many people suffer with post-traumatic stress disorder after surviving a life-threatening ordeal like war, rape or a natural disaster,” explained lead author Dr. Armen Goenjian, a research psychiatrist at the Semel Institute for Neuroscience and Human Behavior at UCLA. He added, “But not everyone who experiences trauma suffers from PTSD. We investigated whether PTSD has genetic underpinnings that make some people more vulnerable to the syndrome than others.”
In 1988, Goenjian, traveled to Spitak, Armenia, after a 6.8 magnitude earthquake devastated the area. Entire towns and cities were leveled by the quake, and more than 25,000 Armenians were killed, two-thirds of them were children. With assistance from the Armenian Relief Society, Dr. Goenjian and his colleagues helped establish two psychiatric clinics that treated earthquake survivors for 21 years. A dozen multigenerational families in northern Armenia agreed to have blood samples drawn and sent to UCLA, where the researchers examined the DNA of 200 individuals for genetic factors related to psychiatric vulnerability.
A new study by Dr. Goenjian’s team found that PTSD was more common in survivors who carried two gene variants associated with depression. In the present study, the researchers focused on two genes called COMT and TPH-2 that play important roles in brain function. COMT is an enzyme that deactivates dopamine, a neurotransmitter that controls the brain’s reward and pleasure centers, and helps regulate mood, thinking, attention, and behavior. Too much or too little dopamine can affect a variety of neurological and psychological disorders.
TPH-2 controls serotonin production; the hormone regulates mood, sleep, and alertness; these processes are all disrupted in PTSD. A group of antidepressants known as selective serotonin re-uptake inhibitors (SSRIs), which treat depression, target serotonin. Many physicians prescribe SSRIs to treat disorders beyond depression, including PTSD. “We found a significant association between variants of COMT and TPH-2 with PTSD symptoms, suggesting that these genes contribute to the onset and persistence of the disorder,” explained Dr.Goenjian. He added,”Our results indicate that people who carry these genetic variants may be at higher risk of developing PTSD.”
The researchers followed the most recent PTSD criteria from the American Psychiatric Association’s diagnostic manual to measure the genetic role in predisposing san individual to the disorder. The new criteria increased estimates of a person’s predisposition for PTSD to 60%t; estimates based on older criteria were only 41%. “Assessments of patients based upon the latest diagnostic criteria may boost the field’s chances of finding new genetic markers for PTSD,” noted Dr. Goenjian. He added, “We hope our findings will lead to molecular methods for screening people at risk for this disorder and identify new drug therapies for prevention and treatment.” He cautioned, however, that it is likely that PTSD is caused by multiple genes and studies should be continued to find additional genes that may be involved.
PTSD affects approximately 7% of Americans and became a major health issue for a large percentage of war veterans returning from tours in Iraq and Afghanistan. “A diagnostic tool based upon PTSD-linked genes would greatly help us in identifying people who are at high risk for developing the disorder,” explained Dr. Goenjian. He added, “Our findings may also help scientists uncover more refined treatments, such as gene therapy or new drugs that regulate the chemicals associated with PTSD symptoms.”
