Beta Blockers and Traumatic Memory: A Dulling Experience

Studies have shown a link between commonly prescribed beta-blockers and the storage of strong, emotionally charged memories.  Taking beta blockers may allow one to dull the emotional trauma of an event by creating a less emotional memory experience.  This could create new treatments for disorders such as PTSD, however whether this is a good way in which to deal with traumatic events remains controversial (1).

            Beta-adrenoceptor antagonists, or beta blockers, are drugs commonly used to treat high blood pressure, migraines, angina and heart problems such as hypertension, myocardial infarction, arrhythmias, and heart failure (2,3,5).  Beta blockers work by inhibiting the body’s normal sympathetic nervous system; they do this by blocking the binding of the stress hormones epinephrine and norepinephrine (2).  This in essence calms the body’s “fight or flight” response.  There are two types of beta receptors, beta-1 and beta-2.  Beta-blocker drugs come in three “generations” the first is non-selective, blocking both beta-1 and 2 receptors, the second is slightly selective for beta-1 receptors and the third generation also blocks alpha-adrenoceptors giving it a slight vasodilator function (2).  In the heart where there are a number of mostly beta-1 receptors, beta blockers function to lower the heart rate, contractility and conduction velocity.  In the blood vessels beta blockers act on beta-2 receptors which play a role in vasoconstriction, however they have a less acute effect than in the heart (2).

            The formation of memories is a complex process which we do not entirely understand.  There are two types of memory: our short term memory, which is limited in capacity and temporally, and our long term memory.  Long term memory is made up of implicit and explicit memories.  Implicit memory includes our perceptual abilities, motor skills, etc. while our explicit memory is what we normally consider “memory”-our personal knowledge and recollections (3).  Memory seems to be enhanced by stress hormones.  Evolutionarily this may have been important for survival, so that we would not repeat dangerous or traumatic encounters.  Strong emotional memories seem to be tied to activation of the basolateral nucleus of the amygdala by stress hormones during these experiences.  Whatever the reason, we find that the strength and significance of a memory is closely tied to its emotional relevance (1).  Furthermore, the emotional response which makes a memory “worth remembering” appears to be tied to the release of stress hormones during the event, as well as during its recollection (3).

            Beta blocker drugs appear to interfere with these strong emotional memories by interfering with the stress hormones epinephrine and norepinephrine.  One recent study supporting this showed that administering beta-blockers affected the normal storage and recall of emotionally charged memories.  This study was comprised of four groups.  Two of these groups heard a neutral story which was illustrated with 12 slides.  One of the groups was administered beta blockers and the other a placebo.  The other two groups were told a similar story, again accompanied by 12 slides, with the addition of an “emotionally arousing” middle section as compared to the first story.  One of these two groups was administered beta blockers and the other was given a placebo.  Results showed that the beta blockers had little effect on the recall of the neutral story-both placebo and beta blocker groups scored similarly on their recollection of the story and associated slides.  However, recall of the emotionally charged story in subjects who were administered beta blockers was similar to those who were told the emotionally neutral story.  Their placebo counterparts, however, had a much greater recall for the emotionally charged section of the story (1,3).  Another recent study involved administering beta blockers to rats who have a learned fear response of a tone associated with a shock.  When the rats are given beta blockers after the tone starts they do not exhibit the stress response that was previously associated with the tone (4, 5).  It seems that beta blockers can dull the emotional stress response to a memory whether they are administered at the time of a traumatic experience, or during the memory of such an event which provokes a similar physical stress response to that which was experienced during the incident (3, 5)

Beta blockers are being looked at as an alternative treatment for posttraumatic stress disorder (PTSD).  PTSD is a debilitating disease that affects about five million Americans at any given time-this means approximately 8% of the population will experience symptoms of PTSD at some point in their life (3).  PTSD is a disorder following a traumatic event that involves severe anxiety or hyper-arousal, reliving the event (often with a severe physical stress response), and emotional numbing (6).   Current treatment involves psychological counseling and exposure therapy.  These treatments only benefit approximately two thirds of patients and may be difficult and painful to undergo (5).  Beta blockers may provide an alternative means of treatment by dulling the emotional memory of a trauma and reducing the physical anxiety that is associated with the memory (3, 5).  Clinical trials having involved the administration of beta blockers versus placebo to emergency room patients post trauma.  Of those who were administered beta blockers none have experienced a physically stressful reaction in response to the recreation of the traumatic event versus the placebo group where six out of fourteen experienced a physical stress reaction (3).  Another clinical trial involved PTSD patients who were administered beta blockers at the onset of symptoms (for example heightened heart rate, or changes in breath patterns), however data is still forthcoming due to the small number of subjects (5).  Overall, clinical trials are ongoing and as of yet are not yet extensive enough for us to reach any conclusions.

Even if beta blockers would help to dull the emotional response of memories in PTSD patients, the question remains as to whether this is an appropriate thing to do.  Although PTSD is a debilitating disease, there may be something to be said for “working through” a memory.  There must be a reason for our emotional connection to certain memories and it seems entirely possible that this is important to the formation of our selves.  Could the administration of beta blockers to dull emotional or traumatic events actually stunt our personal development?  We do not know as of yet what, if any, the adaptive advantages of having strong emotional memories are, and we may not find out until we have gone too far in erasing them (1, 3, 4, 5). 

            It is also concerning to think about the implications of such a drug in relation to violence.  If such drugs were taken by violent criminals could it dull the emotional response and make their reactions to their crimes less negative?  The implications of beta blockers during war could also become a concern.  If the military were to administer such drugs inappropriately could they simply create desensitize soldiers and in doing so create hardened, and experienced killers rather than treat those who by some misfortune experienced a traumatic event (3, 5)?  The implications of misuse of any drug are frightening, however the possibility of a “loss of conscience” due to the loss of emotional memories is particularly alarming.

            As with any new drug treatment, many more clinical trials are needed before beta blockers can safely become a widely used treatment for emotional trauma.  Whether or not they ethically should ever becomes such a treatment is still a question we must carefully consider.  The question of whether or not these drugs will help to quiet a traumatic memory and whether or not doing so is harmful to our development is not an easy one, and may never be fully agreed upon.

    

 

References

 

1)         Pendick, Daniel.  “Unforgettable: Memory Research”.  Memory Disorders Project.  Rutgers        College.  2005.  http://www.memorylossonline.com/winter2005/unforgettable.html

2)         Klabunde, Richard.  “Cardiovascular Pharmacology Concepts: Beta-Adrenoceptor Antagonists (Beta-Blockers)”. 2007.

http://www.cvpharmacology.com/cardioinhibitory/beta-blockers.htm

 3)         LaFee, Scott.  “Blanks for the memories: Someday you may be able to take a pill to forget painful recollections”.  Center for Cognitive Liberty and Ethics.  11 Feb. 2004. http://www.cognitiveliberty.org/neuro/memory_drugs_sd.html 

4)         “Beta-blockers “Blot Out” Memories”. BBC. 28 Jul. 2005.  http://news.bbc.co.uk/2/hi/health/4722225.stm

 5)         Giles, Jim.  “Beta-blockers tackle memories of horror”.  Nature. 28 Jul. 2005.

http://www.nature.com/nature/journal/v436/n7050/full/436448a.html

6)         National Center for PTSD: Fact Sheet.  US Department of Veterans Affiars.  30 Nov. 2007.  http://www.ncptsd.va.gov/ncmain/ncdocs/fact_shts/fs_what_is_ptsd.html