Propranolol treatment of traumatic memories

Jonathan Bisson (2007) discusses the use of propranolol in the prevention of post-traumatic stress disorder, reported in a study by Pitman et al (2002). The latter found encouraging results with patients who had experienced very recent trauma. Brunet et al (2008) reported similar findings in patients with long-term traumatic memories (mean duration of about 10 years). These studies, as well as one by Vaiva et al (2003), recorded physiological measures such as heart rate, but did not report on any clinical benefits, for example reduced distress or changes in the integrity of the traumatic memories.

Almost a decade ago, Nader et al (2000) rekindled the reconsolidation hypothesis of memory. In brief, it proposes that when long-term memories are reactivated through retrieval, they remain labile for several hours before conversion to long-term memory. During this period they are susceptible to amnestic agents such as propranolol. It is thought that propranolol blocks the adrenaline-induced state of high arousal, which is believed to be important in giving traumatic memories their unique quality, including the potency and immediacy they possess (Pitman, 1989).

To explore any clinical benefits in terms of reducing distress and changes in memory integrity, I have treated six patients with a single dose of propranolol, sometimes in conjunction with a single dose of long-acting propranolol. They were asked to retrieve their traumatic memories by talking about them. Bringing these memories into immediate memory was accompanied by varying degrees of visible distress, anxiety and dissociation. They were given propranolol within 3 h of retrieval.

One patient with a 38-year-old memory, who had been on regular atenolol for 14 years, reported no change in the intensity, frequency, integrity or distress associated with the traumatic memory. The other five patients, with memories ranging in age from 4 months to 31 years, all reported improvement. This included ‘fragmentation’ of the memory and difficulty accessing it, minimal or absent distress when thinking about it and a feeling of emotional detachment, as if it were a normal non-traumatic memory or had happened to someone else. Post-treatment, several of the patients requested propranolol treatment for other traumatic memories. Benefits have been maintained for up to 4 months, with no relapse to date. None of the patients reported any negative effects from retrieving the memory, even the patient who did not respond, and side-effects from propranolol (sedation, dry mouth) were mild and transient.

These clinical cases suggest that propranolol may prove to be effective, cheap, simple and safe in the treatment of traumatic memories, which are characteristic of post-traumatic stress disorder. However, randomised controlled trials are needed to confirm any efficacy of this treatment.