Chuck Bednar for redOrbit.com – Your Universe Online
While severe trauma can cause post-traumatic stress disorder, not everyone who experiences such events develop PTSD, and now UCLA scientists believe they know why.
Dr. Armen Goenjian, a researcher at the Semel Institute for Neuroscience and Human Behavior at UCLA, and his colleagues report in the February edition of the Journal of Affective Disorders that they have linked to gene variants to the trauma-related anxiety disorder.
The findings, they explained, could provide a biological basis for diagnosing and treating PTSD more effectively in the future. It could also lead to faster diagnoses for patients, they added.
“Many people suffer with post-traumatic stress disorder after surviving a life-threatening ordeal like war, rape or a natural disaster,” Dr. Goenjian explained. “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.”
Dr. Goenjian, an Armenian American, travelled to that country after a 6.8 magnitude earthquake leveled towns and cities and killed over 25,000 people in 1988. He and his colleagues, with the assistance of the Armenian Relief Society, established a pair of psychiatric clinics that provided treatment to survivors of the earthquake for more than two decades.
Twelve multigenerational families in northern Armenia gave permission to have their blood samples sent to UCLA, where Dr. Goenjian and his colleagues analyzed the DNA of 200 men and women in search of genetic clues to psychiatric vulnerability.
In April 2012, research by his team revealed that that PTSD was more common in survivors who carried two gene variants associated with depression. Now, along with UCLA Fielding School of Public Health adjunct assistant professor of epidemiology Julia Bailey, Dr. Goenjian focused on two genes (COMT and TPH-2) known to play key roles in the function of the brain.
COMT, the researchers explain, is an enzyme that degrades the neurotransmitter dopamine, which controls the reward and pleasure center of the brain and helps regulate mood. Too much or too little dopamine can influence various neurological and psychological disorders, they said.
TPH-2, on the other hand, controls the production of the brain hormone serotonin, which regulates mood, sleep and alertness. All three are affected by PTSD, and a type of antidepressant known as selective serotonin re-uptake inhibitors (SSRIs) target the hormone to treat depression. An increasing number of doctors are prescribing them to treat PTSD, the study authors noted.
“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,” Dr. Goenjian explained. “Our results indicate that people who carry these genetic variants may be at higher risk of developing PTSD.”
Using the most latest criteria for PTSD from the American Psychiatric Association’s diagnostic manual, they measured the role of these genes in predisposing a person to the condition. The new criteria increased estimates of a person’s predisposition for the anxiety disorder to 60 percent, while estimates using an older criteria for PTSD only reached 41 percent.
“Assessments of patients based upon the latest diagnostic criteria may boost the field’s chances of finding new genetic markers for PTSD,” Dr. Goenjian explained. “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.”
However, he cautioned that post-traumatic stress disorder, which affects approximately seven percent of Americans, is likely caused by multiple genes. Continued research into the condition should be pursued in order to discover more of the genes involved, Dr. Goenjian added.
“A diagnostic tool based upon PTSD-linked genes would greatly help us in identifying people who are at high risk for developing the disorder,” he said. “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.”
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