The connection between stress and blood pressure seems like common sense. Of course experiencing stress — like a narrow miss in morning traffic or dealing with a stubborn, whiny child — raises someoneâ€™s blood pressure.
Try reversing the cause-and-effect relationship: not from brain to body, but instead from body to brain. Could medication for controlling blood pressure moderate the effects of severe stress, and thus aid in controlling PTSD symptoms or in preventing the development of PTSD after trauma?
That was the intriguing implication arising from a 2012 paper from Grady Trauma Project investigators led by psychiatrist Kerry Ressler (lab at Yerkes, supported by HHMI).
They had found that traumatized civilians who take either of two classes of common blood pressure medications tend to have less severe post-traumatic stress symptoms. In particular, individuals taking ACE inhibitors (angiotensin converting enzyme)Â or ARBs (angiotensin receptor blockers)Â tended to have lower levels of hyperarousal and intrusive thoughts, and this effect was not observed with other blood pressure medications.
This was one of those observational findings that needs to be tested in an active way: â€œOK, people who are already taking more X experience less severe symptoms. But can we actually use X as an intervention?â€
In mice, it seems to work. Paul Marvar, an Emory postdoc who is starting a faculty position at George Washington University, and Ressler recently published a paper in Biological Psychiatry demonstrating that a two-week course of the ARB losartan (even a single dose works, actually) enhances extinction of fear memory.
Extinction of fear memory is a process that is poorly regulated in humans with PTSD. It allows the mice to become less afraid of a tone that is usually paired with a shock.
A short course of losartan did not actually lower basal blood pressure in the mice, and it did not influence whether mice could acquire fear (that is, become afraid of a tone). Previous animal studies on the effects of angiotensin receptor blockers on learning and memory have been inconsistent, the authors note in the paper.
Losartan is FDA-approved for the treatment of hypertension, and a paragraph in the discussion gives you an idea of the direction the authors are heading:
Future questions for translating our current findings into potential novel therapies include identifying the appropriate timing and use of AT1 receptor antagonists as therapy after trauma exposure and determining whether circulating levels of angiotensin II are altered in http://www.raybanoutletes.com/ patients diagnosed with PTSD and whether angiotensin receptor polymorphisms are present in these patients. Future studies are therefore aimed at further understanding these questions and the mechanism, because inhibition of this pathway might serve as a safe, powerful, and novel treatment for PTSD.