In what they termed the "largest [genome-wide association study] of anxiety traits to date," a team of scientists from two universities and two veterans healthcare offices have identified six genetic variants linked to the development of anxiety disorders.
To find these genetic markers, researchers examined genetic and health data derived from 200,000 veterans of the United States Armed Forces, which was compiled in the Million Veteran Program (MVP), a national research program funded by the government to determine "how genes, lifestyle and military exposures affect health and illness."
"This is the richest set of results for the genetic basis of anxiety to date," Joel Gelernter, the co-lead author of the study, said in a Yale press release.
The researchers, who represented Yale University, the Veterans Affairs (VA) San Diego Healthcare System, the Veteran Affairs Connecticut Healthcare System and the University California, San Diego, shared their findings in a study published in the American Journal of Psychiatry on Tuesday.
According to information from the Anxiety and Depression Association of America, anxiety disorders are one of the most prevalent mental health issues in the U.S., and affect some 40 million adults in the country every year. A number of factors contribute to the development of an anxiety disorder, including past life experiences, brain chemistry and genetic makeup.
"While there have been many studies on the genetic basis of depression, far fewer have looked for variants linked to anxiety, disorders of which afflict as many as 1 in 10 Americans," the study's senior author, Murray Stein, said in a press release from Yale. Stein a staff psychiatrist in the VA San Diego Healthcare System.
In their analysis of the veterans' genomic data, they found six genetic variants associated with higher risks of developing anxiety disorders. Five of these were found in white Americans, while an additional one was found in black Americans. However, Stein wrote in an email to Newsweek that more testing would be required to fully confirm the link between anxiety and the variant found in black Americans.
"The African ancestry sample is smaller, so we have less ability to be confident about our findings; larger samples are needed and MVP is continuing to do that," he wrote.
Dan Levey of the VA Connecticut Healthcare Center and Yale University, another author of the study, said that it was important to include data from minorities in the study.
"Minorities are underrepresented in genetic studies, and the diversity of the Million Veteran Program was essential for this part of the project," Levey said in a news release from the VA. "The genetic variant we identified occurs only in individuals of African ancestry, and would have been completely missed in less diverse cohorts."
The variants that were determined to relate to anxiety disorders were found on chromosomes 1, 3, 6, 7 and 20. One of the variants, the one on chromosome 7, was previously identified to be correlated with higher occurrences of bipolar disorder and schizophrenia.
Another variant, the one on chromosome 7, was associated with the reception of the sex hormone estrogen. However, researchers cautioned those reading the study from drawing conclusions on if this explains why women are affected by anxiety disorders twice as frequently as men. While women veterans were included in this study, more than 90 percent of the veterans whose data is part of the Million Veteran Program are male. Thus, the researchers cited that more research is necessary to confirm or disprove the suspicion.
Stein stressed in his email to Newsweek that understanding the precise relationship between the genetic variants and anxiety disorders would require further scientific inquiry.
"We think that more research needs to be done that will enable us to see how these and other genes influence development of different types of anxiety disorders (e.g., social anxiety, panic disorder, generalized anxiety disorder)," Stein wrote. "It is likely that some genes confer increased risk in general, whereas other genes influence more specific manifestations of anxiety. Even larger sample sizes will be needed to make this determination."
Nevertheless, the writers of the study believed that their research was a good step in the right direction in determining what factors cause anxiety.
"This work provides new insights into genetic risk mechanisms underpinning anxiety and related psychiatric disorders," they wrote.
01/13/20, 5:07 p.m.: This story has been updated to include a response to Newsweek about the study from the study's senior author Murray Stein.
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