The horrible nightmares. An American soldier serving in Iraq reaches out for support in his recent website post. “Last night I dreamed I was flying in a Blackhawk to another FOB and blood was covering the seats and the floor of the bird. There was so much that I was scooping it out the door with my hands. It’s starting to effect my sleep a lot.”
Serious sleep disturbance from nightmares is one of the most debilitating consequences of post-traumatic stress disorder (PTSD), affecting 70%-87% of patients suffering the psychological trauma. Psychiatrists empty the drug cabinet in a trial-and-error search for a medicine that will bring relief to people with PTSD. Everything from antidepressants, anxiolytics, antipsychotics, sedatives, to mood stabilizers is prescribed for PTSD. Now there is a surprising new approach: grandma’s high blood pressure medicine.
A connection between high blood pressure and nightmares terrorizing people with PTSD seems odd at first, until you consider what the body’s natural response to stress is. The first switch thrown in our fear response jump-starts our heart rate powering a surge in blood pressure. This familiar adrenalin-fueled boost is the body’s way of revving up all systems for the fight or flight response to any life-threatening situation. The high blood pressure medicine, prazosin, dampens adrenalin’s effect on the heart and blood vessels by blocking receptors for the hormone. High blood pressure medicine is the newest approach to treating PTSD, and the studies are still underway, but the data thus far show that seventy-five to eighty percent of PTSD patients who try prazosin stop having nightmares and sleep through the night with normal dreams.
But how could reducing blood pressure have any effect on nightmares and reliving horrific memories of traumatic events? The answer is that adrenalin’s effects are hardly limited to our cardio-vascular system; adrenalin also has a powerful effect on the brain. Any event that is accompanied by extreme stress is burned into memory by adrenaline stamping the experience as life-threatening and something that should never be forgotten. In contrast to the repetition necessary to write most events into long-term memory, a traumatic event is seared into memory permanently after one experience. You will never forget any truly life-threatening experience, and the adrenalin surge is what marks that experience as life-threatening to encode it permanently into memory.
A similar high blood pressure drug, propranolol, works the same way, and it is being used to “erase” traumatic events from memory by having the patient recall the traumatic event that caused the PTSD while the adrenaline response is dampened with the medication. The memory loses its association with danger when the adrenalin signal is suppressed, and it begins to fade. This forced recall re-enacts what happens naturally in our head every night at rest on our pillow. Recent research shows that as we sleep we unconsciously sort through our daily experiences, associate them with other memories, and decide which ones to discard and which to keep. So using high-blood pressure medicine to relieve nightmares and dampen the horror of traumatic memories makes good sense in light of how memory is stored.
For more on the subject of memory and erasing traumatic ones, see my articles in Scientific American Mind and Odyssey Magazine below.
Berger, W., et al., (2009) Pharmacologic alternatives to antidepressants in posttraumataic stress disorder: A systematic review. Progress in Neuro-Psychopharmacology and Biological Psychiatry 33: 169-180.
Fields, R.D. (2008) Erasing Memory Odyssey, May/June 6-11
Fields, R.D. (2008) Lost, Odyssey May/June 12-15.
Fields, R.D. (2005) Erasing memories. Scientific American Mind November 16:28-37
Fields, R.D. (2006) Unforgettable. Odyssey November, 38-40.
Fields, R.D. (2005) Making memories stick. Scientific American 292 (February), 74-81.
Fontaine, S (2009) Blood pressure pill slays nightmares. The Washington Post, Dec. 31, 2009, p. A15.
Miller, L.J. (2008) Prazosin for the treatment of posttraumatic stress disorder sleep disturbances. Pharmacotherapy 28: 656-666.