Developing post-traumatic stress disorder (PTSD) following traumatic events has a strong genetic component, a new study shows.
The large collaborative study, conducted by over 130 research institutions participating in the Psychiatric Genomics Consortium, has identified six distinct genetic loci that form a biological basis for PTSD similar to other psychiatric disorders.
'Based on these findings, we can say with certainty that there is just as much of a genetic component to PTSD risk as major depression and other mental illnesses,' said senior author Professor Karestan Koenen at Harvard University in Boston, Massachusetts.
'Our long-term goal is to develop tools that might help clinicians predict who is at greatest risk for PTSD and personalise their treatment approaches,' added the study's first author Dr Caroline Nievergelt from the University of California, San Diego.
Published in Nature Communications, it is the largest and most diverse genetic analysis of PTSD to date. Samples from more than 60 multi-ethnic groups of PTSD-affected and non-affected individuals from 12 countries were collected, including a UK BioBank dataset. Among the 200,000 subjects, over 30,000 PTSD cases were recorded, including a large fraction of people with European and African ancestry.
'Our study is distinguished by the fact that it's international and is highly diverse,' said Dr Nievergelt. 'There's greater representation here than in most studies to date.'
The study measured the effect of common genetic variants across the genome on someone's likelihood of developing PTSD. The heritability of PTSD was estimated between five and 20 percent, depending on sex, showing the disorder to be highly polygenic. Six genetic loci were strongly associated with PTSD risk and hint at the involvement of inflammatory and immune mechanisms. Furthermore, the genetic basis for PTSD significantly overlapped with 21 other disorders, behaviours and physical traits, including depression and schizophrenia.
Although not ready for clinical use, the authors used the findings to create a polygenic risk score for PTSD. This score is based on the effect of millions of genetic variations and could be used as a predictive measure for an individual's likelihood of developing PTSD after a traumatic event. The study concluded that larger studies with more diverse datasets are needed to develop more robust and accurate polygenic scores.
'This is a good start, but this needs to be a truly inclusive, large-scale, team-based scientific effort if we're going to continue to lay the groundwork for more effective interventions and treatments for the millions of people struggling with PTSD,' Professor Koenen said.