Building on earlier findings that demonstrated there is some shared genetic overlap between post-traumatic stress disorder (PTSD) and other mental disorders such as schizophrenia, the study also found that genetic risk for PTSD is strongest among women. Senior author Karestan Koenen said:
“We know from lots of data, from prisoners of war, people who have been in combat, and from rape victims, that many people exposed to even extreme traumatic events do not develop PTSD. Why is that? We believe that genetic variation is an important factor contributing to this risk or resilience.”
Koenen is professor of psychiatric epidemiology at Harvard T.H. Chan School of Public Health, and leads the Global Neuropsychiatric Genomics Initiative of the Stanley Center for Psychiatric Research at Broad Institute.
Genetics In PTSD
Researchers analyzed over 200 billion points of genetic information from more than 20,000 adults in 11 multi-ethnic studies around the world. It presents a robust case for the role of genetics in PTSD, which had been previously documented on a smaller scale in studies of twins.
The researchers discovered patterns in the data that showed people with PTSD were more likely to have the same alleles, or versions of genes, while those without the disorder had different versions.
Post-traumatic stress disorder is a common and debilitating mental disorder that occurs after traumatic events. Symptoms include chronic hyperarousal, re-experiencing the traumatic event, and avoiding stimuli related to the event.
In the U.S., one in nine women and one in twenty men will meet the criteria for a post-traumatic stress disorder diagnosis at some point in their lives. The societal impact is large, including increased rates of suicide, hospitalization, and substance use.
Intervention And Prevention
The genome-wide genomic data indicated that among European American females, 29% of the risk for developing PTSD is influenced by genetic factors, which is comparable to that of other psychiatric disorders. In contrast, men’s genetic risk for PTSD was substantially lower.
“PTSD may be one of the most preventable of psychiatric disorders,” said first author Laramie Duncan. “There are interventions effective in preventing PTSD shortly after a person experiences a traumatic event. But they are too resource-intensive to give to everyone. Knowing more about people’s genetic risk for PTSD may help clinicians target interventions more effectively and it helps us understand the underlying biological mechanisms.”
The team also uncovered strong evidence that people with higher genetic risk for several mental disorders, including schizophrenia, and to a lesser extent bipolar and major depressive disorder, are also at higher genetic risk for developing PTSD after a traumatic event.
The reasons behind the stronger genetic link in women are not yet clear, according to Duncan. Speaking to CTV News Channel, she said:
“For a lot of different medical conditions, it seems like the genetic influence on women is a little bit stronger than it is for men.”
Laramie E. Duncan, Andrew Ratanatharathorn, Allison E. Aiello, Lynn M. Almli, Ananda B. Amstadter, Allison E. Ashley-Koch, Dewleen G. Baker, Jean C. Beckham, Laura J. Bierut, Jonathan Bisson, Bekh Bradley, Chia-Yen Chen, Shareefa Dalvie, Lindsay A. Farrer, Sandro Galea, Melanie E. Garrett, Joel E. Gelernter, Guia Guffanti, Michael A. Hauser, Eric O. Johnson, Ronald C. Kessler, Nathan A. Kimbrel, Anthony King, Nastassja Koen, Henry R. Kranzler, Mark W. Logue, Adam X. Maihofer, Alicia R. Martin, Mark W. Miller, Rajendra A. Morey, Nicole R. Nugent, John P. Rice, Stephan Ripke, Andrea L. Roberts, Nancy L. Saccone, Jordan W. Smoller, Dan J. Stein, Murray B. Stein, Jennifer A. Sumner, Monica Uddin, Robert J. Ursano, Derek E. Wildman, Rachel Yehuda, Hongyu Zhao, Mark J. Daly, Israel Liberzon, Kerry J. Ressler, Caroline M. Nievergelt, Karestan C. Koenen Largest GWAS of PTSD (N=20,070) Yields Genetic Overlap with Schizophrenia and Sex Differences in Heritability Molecular Psychiatry, April 2017 DOI: 10.1038/MP.2017.77