The observed methylation changes in the immune system genes were reflected in the PTSD participants' immune systems: levels of antibodies to a herpes virus were high in PTSD patients, indicative of a compromised immune system.

While people who experience severe trauma will exhibit a normal stress response, in PTSD, the stress response system becomes deregulated and chronically overactive causing compromised immune functioning. PTSD has long been linked to increased risk of numerous physical health problems - including diabetes and cardiovascular disease. This paper suggests why PTSD is so strongly associated with physical health problems - trauma exposure causes epigenetic changes in immune system genes and thus, compromised immune functioning putting individuals at risk for a host of disorders.

"Our findings show that PTSD may be associated with epigenetic changes in immune-system genes. If this is the case, these clusters could provide clues to our understanding of how a traumatic event changes gene expression, thus altering immune function and resulting in other possible physiologic alterations," says Dr. Galea.

Source: Columbia University's Mailman School of Public Health