Study Uncovers Genetic Risks for PTSD
PTSD is a mental health condition that appears in a substantial minority of people who go through traumatic experiences such as combat exposure and rape and other forms of sexual or physical assault. The illness has a range of known risk factors. In a study published in February 2015 in the Journal of Affective Disorders, researchers from four U.S. institutions assessed the impact that two genetic variations affecting the brain’s chemical environment have on the odds that exposure to traumatic events or situations will result in the onset of PTSD.
Known PTSD Risk Factors
Thirty days or more after exposure to highly dangerous or life-threatening circumstances, roughly 20 percent of American women and 8 percent of American men will develop diagnosable symptoms of post-traumatic stress disorder. (Symptoms that appear prior to the minimum 30-day time period are grounds for the diagnosis of another related condition called acute stress disorder.) Over the course of their lifetimes, about 60 percent of U.S. men will encounter situations or events linked to the onset of PTSD; U.S. women have an approximately 50 percent lifetime rate of exposure to such situations and events.
Several factors influence a person’s chances of developing PTSD in the wake of highly traumatic circumstances, the National Center for PTSD reports. These factors include the severity and duration of the trauma, the strength of the individual’s initial response to trauma exposure, the amount of control the individual feels he or she had over trauma exposure, whether or not traumatic circumstances resulted in an injury to the individual or a loved one and the availability and use of support in the aftermath of trauma exposure. Apart from women, population groups known to have increased odds of developing the disorder include people of non-Caucasian racial/ethnic descent, people with pre-existing mental health issues, people already undergoing significant life stress, people with a prior history of exposure to traumatic events/situations and people with non-existent or poorly developed personal and social support networks.
Mental Health and Genetics
Genetic variations are alternate versions of the genes that control the basic aspects of human growth and development in addition to helping determine how the human body functions in adulthood. Some genes have one common or rare variation, while others have multiple possible variations. In addition, some genes don’t typically have any alternate forms. Researchers have previously tied increased risks for the presence of at least five mental health conditions to genetic variations in human DNA, the National Institute of Mental Health notes. These conditions are major depression, bipolar disorder, schizophrenia, autism spectrum disorder and attention-deficit hyperactivity disorder (PTSD).
PTSD and Genetic Risk
In the study published in the Journal of Affective Disorders, researchers from the University of California at Riverside, the University of California, Los Angeles and two other institutions used information gathered from a group of 200 people from the Republic of Armenia to help identify genetic variations that increase the odds of developing PTSD. All of the study participants were survivors of a severe 1988 earthquake in that country. For 20-plus years, the researchers tracked the rate of PTSD in these participants. They also looked for the presence of variations in two specific genes. One of the genes under examination helps control levels of a brain chemical called dopamine, while the other helps control levels of a brain and body chemical called serotonin. Dopamine plays a role in regulating such things as pleasurable sensations, mood and behavioral control. Serotonin plays a role in regulating things such as sleepiness/alertness and mood.
After completing their work, the researchers concluded that study participants with specific variations of the two genes under consideration were substantially more likely to develop PTSD symptoms than their counterparts who did not have the same genetic variations. In combination, the variation in dopamine regulation and the variation in serotonin regulation apparently boost the chances of developing such symptoms by roughly 7 percent.
The study’s authors believe their findings indicate that there may be a meaningful genetic risk for the onset of post-traumatic stress disorder. They note that recent changes in the official definition of PTSD have made this potential genetic risk more clear than previously understood.