THURSDAY, Sept. 24, 2015 (HealthDay News) -- Even though survivors of childhood physical or sexual abuse can face a higher risk for depression as adults, not everyone will become depressed.
Now, new Australian research points to DNA as a potential factor in determining who will suffer depression later on. Scientists say they've spotted a gene variant that appears to raise the odds of depression in adults who suffered childhood abuse.
There's a twist, however: People with the same gene variant who never suffered abuse actually tend to be happier than similar people without the gene, the researchers found.
"Our results suggest some people have a genetic makeup that makes them more susceptible to negative environments, but if put in a supportive environment these same people are likely to thrive," lead investigator Dr. Chad Bousman, of the University of Melbourne, said in a university news release.
In the study, his team focused on the SERT gene, which transports the mood-regulating brain chemical serotonin. Every person has one of three types of this gene: the long-long, the short-long, or the short-short.
The study included more than 300 middle-aged Australians of northern and western European ancestry who underwent genetic testing. The participants also had their symptoms of depression recorded over five years.
People with the short-short version of the SERT gene who suffered childhood physical or sexual abuse were more likely to have severe depression, Bousman's team found.
On the other hand, people who had the same version of the gene but no history of abuse tended to be happier than other study participants.
The findings, published Sept. 22 in the British Journal of Psychiatry Open, appear to challenge traditional thinking about depression and could lead to better methods of treatment, the study authors said.
In the meantime, Bousman said, none of this means that a person's DNA guarantees they will suffer depression, even if they suffered trauma in childhood.
"It's not as clear-cut as telling a person that because they have a risk gene, they're doomed. This research is showing that's not the case at all," he said.
And while "you can't change your [genetic makeup] or go back and change your childhood... you can take steps to modify your current environment," Bousman said.
"A person's genes alone are not enough to determine how they might experience depression," he explained. "This research tells us that what may be considered a risk gene in one context, may actually be beneficial in another. So this directly opposes the notion of genetic determinism, the idea that your genes define your fate."
The American Academy of Family Physicians has more about depression.