A Psychophysiologic Study of Weakening Traumatic Combat Memories With Post-Reactivation Propranolol

Study Summary

The consolidation of learning is enhanced by adrenalin and other stress hormones. This memory enhancing effect is opposed by propranolol. In posttraumatic stress disorder (PTSD), a psychologically traumatic event may overstimulate stress hormones such as adrenalin, which in turn overly strengthen consolidation of the memory of the event, leading to an excessively powerful and persistent memory. Administration of propranolol after a psychologically traumatic event could reduce subsequent PTSD. Unfortunately, there exists a window of opportunity for influencing the consolidation of a traumatic event into long-term memory. In persons who have already developed PTSD, this would have closed months or years earlier. However, recent developments in animal research suggest that reactivation (retrieval) of a consolidated memory can return it to a labile state, from which it must be restabilized in order to persist. This process, which has been termed "reconsolidation," can be reduced in animals by propranolol. In a preliminary study performed by the PI and colleagues in Canada, civilian participants with PTSD described the traumatic event during a script preparation session, which served to reactivate their traumatic memory. They then received either propranolol or placebo. A week later, during script-driven imagery of their traumatic events, physiologic responses were smaller in the participants who had received post-reactivation propranolol compared to placebo, suggesting that the traumatic memory had been weakened by the propranolol. These results suggest that that post-reactivation propranolol recapitulates its effects on consolidation, this time by blocking reconsolidation of the traumatic memory. Several important questions remain unanswered. First, does propranolol also weaken traumatic memories in combat-related PTSD? Second, does this weakening effect only occur when the propranolol is given after combat memory reactivation? If not, this would refute the reconsoli

Primary Outcome

The posterior probability of developing PTSD was determined for each participant from a composite of psychophysiological responses during script-driven imagery of traumatic combat events that included assessments of heart rate response in beats per minute, skin conductance response in microSiemens, and corrugator and left lateral frontalis facial muscle electromyogram (EMG) responses in microVolts. Responses for the two traumatic scripts were averaged and square-root transformed for analysis. Re

Conditions Studied

Interventions

• DRUG Placebo
• DRUG Propranolol

Study Locations (3)