Researchers have found immune-system irregularities that may help identify and eventually predict post-traumatic stress disorder (PTSD). These irregularities were found in genes taken from white blood cells, suggesting that this brain-based disorder may be reflected in gene expression in other parts of the body.

The research team looked at genes from white blood cells in U.S. Marines before and after deployment to Iraq and Afghanistan, an event associated with increased likelihood of PTSD. Although other research has linked genes that regulate bodily inflammation with PTSD, this is the first study to pin down telltale patterns of activity among groups of immune system-regulating genes, both before and after symptoms appear.

The findings were published March 10th in Molecular Psychiatry by a team including NARSAD-funded investigators Ming T. Tsuang, M.D., Ph.D., a Foundation Scientific Council member and 1998 Distinguished Investigator grantee; Stephen J. Glatt, Ph.D., a 2006 and 2009 Young Investigator grantee and 2013 Independent Investigator grantee; and Victoria B. Risbrough, Ph.D., a 2006 Young Investigator grantee.

Using techniques to track groups of genes with related activity, the researchers identified clusters of genes whose expression was tied to the presence or absence of PTSD. Among the Marines with PTSD, there was increased activity for certain genes known to regulate immune system responses. Among the Marines who did not have PTSD, there was greater activity in genes associated in some people with blood clotting, one of the first stages of wound healing.

These patterns appeared both before and after military deployment, suggesting that the relevant gene expression reflects causal processes that continue after the disorder takes hold.  The patterns held across two independent groups of Marines. This consistency suggests that disrupted immune system regulation may truly underlie the pathology of PTSD, whereas stronger wound healing is associated with PTSD resilience.  

These patterns may eventually be used to predict which individuals are susceptible to PTSD, although more work needs to be done to understand exactly how these gene networks function in relation to symptoms. The scientists call for more research into how a disorder strongly characterized by pathology of the brain could be shaped by gene expression in white blood cells, which are usually blocked from entering the brain.

Read the abstract.