A group of researchers found several locations in the human genome linked to flashbacks, a hallmark symptom of posttraumatic stress disorder (PTSD), according to a new study published in the journal Nature Neuroscience.
PTSD is characterized by prolonged symptoms of severe anxiety, depersonalization/derealization, dysthymia, flashbacks, nightmares, and insomnia after witnessing or experiencing a traumatic event.
For the study, the research group compared the genomes of 146,660 European Americans and 19,983 African Americans to spot any genetic risk factors associated with re-experiencing traumatic memories, or flashbacks. All participants had volunteered for the US Million Veteran Program.
Among white veterans, researchers identified eight regions in the genome. “In European Americans, eight distinct significant regions were identified. CAMKV; chromosome 17 closest to KANSL1, but within a large high linkage disequilibrium region that also includes CRHR1; and TCF4,” said Joel Gelernter, lead author of the study.
No significant regions were identified in black veterans, however, likely as a result of fewer participants.
The findings revealed a genetic overlap linking PTSD to numerous other psychiatric and medical illnesses. For instance, two genes associated with psychotic disorders were found to be linked to flashback symptoms of PTSD. Hallucinatory states induced from psychotic disorders might share similar biochemical pathways like flashbacks observed in PTSD. Moreover, the study found flashbacks also shared genetic risk factors with hypertension, as previous studies suggest.
Researchers were also able to strengthen previous findings on the development of PTSD. The new findings strongly link processes associated with CRHR1 to PTSD. “These results provide new insights into the biology of PTSD in a well-powered genome-wide association study,” said Gelernter.
The vast genome-wide association study, based on the Million Veteran Program of the US Department of Veteran Affairs, was conducted in collaboration with Yale University School of Medicine and the University of California San Diego.