Two new studies demonstrate quite different bodily reactions to chronic post-traumatic stress disorder, with men showing no immune response and women showing a strong immune response.
While the immune system is critical to protecting the body from bacteria and viruses, an over-activated response causes inflammation, which can lead to such conditions as cardiovascular disease and arthritis.
In the study the authors took blood samples from 49 men (24 with PTSD and 25 controls) and 18 women (10 with PTSD and 8 controls). They then used gene microarray technology to determine immune reaction in both the body and brain.
“We were looking for evidence of inflammation caused by immune activation,” explained lead author Thomas Neylan, M.D. “We know that people with PTSD have higher rates of cardiovascular disease and arthritis, which are diseases associated with chronic inflammation. We also hoped that seeing which genes were expressed in PTSD might show us potential therapeutic approaches that we hadn’t thought of.”
The researchers found no evidence of increased immune activation among the men with PTSD compared to those without PTSD.
In contrast, the women with PTSD showed significant evidence of immune activation compared to women without PTSD.
Researchers say the finding was unexpected and they are unsure why there seems to be such a marked difference between men and women.
Neylan emphasized that because of the small sample size, particularly among the women, the results of the two studies are suggestive rather than conclusive. “The next step is to look at larger groups of men and women, and we are working on that,” he said.
The study was published in the journal Brain, Behavior, and Immunity.
A study published in the January 2011 issue of the journal Disease Markers posited one possible explanation: the gender differences result from circulating hormones and proteins produced in response to signals from the brain or central nervous system.
According to lead author Aoife O’Donovan, Ph.D., “These signaling pathways are used by the brain and central nervous system to communicate with the immune system and tell immune cells what to do.”
O’Donovan believes the bioinformatics results “are telling us something about how PTSD could increase the risk for autoimmune disorders like arthritis as well as cardiovascular disease, cancer, and other diseases of aging. They also point us in the direction of some potential treatment targets, telling us where future investigative energy might be well spent.”