In a new study, researchers have discovered that multiple locations in the human genome related to the risk of re-experiencing traumatic memories.
This symptom is the most distinctive symptom of PTSD.
The research was based on the Million Veteran Program of the U.S. Department of Veterans Affairs.
PTSD is usually considered to have three main clusters of symptoms: re-experiencing, avoidance, and hyperarousal.
Avoidance and hyperarousal are common to other anxiety conditions as well, but re-experiencing is largely unique to PTSD.
Re-experiencing refers to intrusive thoughts, nightmares, and flashbacks of the traumatic event.
In the study, the team examined the vast genetic and health record data from more than 165,000 veterans.
They identified gene variants that increase the likelihood of PTSD re-experiencing.
They found eight separate regions in the genome linked to re-experiencing symptoms among the white veterans.
It did not show any significant regions for black veterans, considered separately as a group, because there were far fewer black study participants available, making it harder to draw conclusions.
The association between PTSD re-experiencing and common variants in three of these genome regions were highly significant: gene CAMKV, a region near genes KANSL1 and CRHR1, and gene TCF4.
These key results were replicated using the UK Biobank sample, which has about 500,000 participants.
The results also showed a genetic overlap between PTSD and many other psychiatric, behavioral, and medical conditions.
Two genes previously linked to schizophrenia and bipolar disorder were found to be linked to re-experiencing in PTSD.
This means that the hallucinations experienced in schizophrenia may share common biochemical pathways with the nightmares and flashbacks of people with PTSD.
The team also found that re-experiencing shares genetic risk factors with high blood pressure. Previous studies found that PTSD and high blood pressure often occur together.
This result suggests that the link could be at the genetic level.
The researchers explain that the finding could lead to new drug treatments based on patients’ genes.
It is possible that high blood pressure drugs that affect these same genes could be effective for treating PTSD.
Researchers from the VA Connecticut Healthcare System, Yale University School of Medicine, the VA San Diego Healthcare System, and the University of California San Diego collaborated with colleagues on this large genome-wide association study.
The study is published in the journal Nature Neuroscience.
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