People diagnosed with post-traumatic stress disorder (PTSD) have been found to have genetic changes in their DNA, making them different from healthy people, (see online May 3 in the Proceedings of the National Academy of Sciences). The researchers found that there were dramatic differences between the immune system genes and brain cell growth genes of people with PTSD and people who do not have PTSD.
These differences are reported to likely cause significant pathophysiologic and psychopathological problems in PTSD patients, specifically causing subsequent:
- immune system dysfunction,
- emotional changes,
- hyperarousal, and
- exaggerated startle responses to sound*
*”(changes) … measured via heart rate or skin conductance after exposure to a sudden, loud tone, have been well documented among thePTSD affected (30) and are indicative of a hyperarousal state that characterizes this symptom domain.”
Proceedings of the National Academy of Sciences “Epigenetic and immune function profiles associated with posttraumatic stress disorder”
“Recent work suggests that epigenetic DNA methylation changes may accompany lifetime experiences and alter gene expression profiles (7). This work has particular promise for the study of PTSD given the direct link between an experience (i.e., a PTE) and a physiologic manifestation of illness.”
Background Explanations of pertinent terminology: “Epigenetics” is the study of changes in DNA, RNA, etc that accumulate as an organism (like us) as we age. In the old argument of Nature vs. Nurture, it was incorrectly assumed that our basic inherited DNA & RNA had a fixed set of properties, but it has been demonstrated that the things we eat, the air we breathe, the stress we experience, and life in general affect what parts of our DNA and RNA remain intact, how much damage it receives, which parts of our genes are turned-ON or turned-OFF.
This means that Nurture (our environment) effectively changes our Nature (our inherited DNA) over time: which explains why identical twins have very close expressions (nearly identical phenotypes) of their DNA, health risks, etc, while later at age 60, one twin may have elevated cancer risk due to their tobacco use that changed their DNA. “Methylation” of DNA means that a methyl (-CH3 group) has been attached to a single molecule in our DNA chain – which blocks the gene with the added methyl group – and prohibits that gene from ever encoding it’s protein ever again – which is a way of saying that gene can never again do it’s job of making an important enzyme, or sending a messenger molecule to signal hormone production, etc.
These scientists did a very large study evaluating methylation profiles at more than 27,000 CpG gene sites covering more than 14,000 genes in 100 people, 23 of whom were confirmed PTSD patients. They found that there were dramatic differences in the amount of methylation of immune system genes between the PTSD patients and the non-PTSD patients. Their study found that PTSD patients had far less methylation of key immune system genes, which effectively permanently impaired immune system function in the PTSD patients.
Even though the findings showed differences between people with and without PTSD, they do not shed light on whether these differences might play a role in PTSD, says study coauthor Sandro Galea, a physician and epidemiologist at Columbia University in New York City. “There is evidence that PTSD is involved in immune dysfunction, and we suggest that that’s part of a larger process,” Galea says. Although previous studies have also suggested a PTSD link to immune gene activation, the connection is unclear.
A final Yucalandia observation: Specifically, the researchers found that PTSD patients showed less methylation in several immune system genes and more methylation in genes linked to the growth of brain cells – which may explain the short term memory losses and weaker immune systems in PTSD patients. Finally, these findings would explain why both sets of these symptoms get worse over time in people with PTSD, due to epigenetics changes that accumulate as the individuals get older.
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© Steven M. Fry
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