Propranolol's impact on cognitive performance in post-traumatic stress disorder.

BACKGROUND: Propranolol has effectively diminished fear-based emotional memories in posttraumatic stress disorder (PTSD) and this effect has been attributed to traumatic memory reconsolidation blockade. However, propranolol may also exert cognitive effects by modulating stress and arousal.

METHOD: Within a randomized double-blind placebo controlled trial, propranolol's impact on cognitive functioning was examined in individuals who were diagnosed with chronic PTSD. Participants received a single dose of 1mg/kg of propranolol (n=20) or placebo (n=21), and completed subtests of the Wechsler Adult Intelligence Scale third edition (WAIS-III). PTSD symptoms were assessed 1 week before and after treatment by the Impact of Event Scale Revised (IES-R).

RESULTS: The propranolol group performed significantly better on the Processing Speed composite measure compared to the placebo group. Furthermore, greater heart rate decreases were associated with higher Perceptual Organization performance, within the propranolol group.

LIMITATIONS: The generalizability of results may have been reduced as participants were treatment seeking; the sample size was small and included a greater proportion of females.This study could not assess whether pre-existing psychological function influenced cognitive performance, post-trauma. Future studies might consider including a non-PTSD control group to determine if our findings are specific to propranolol's effect on PTSD associated cognitive impairment.

CONCLUSIONS: Our preliminary results demonstrated that cognitive functioning improved following propranolol administration in PTSD patients. The implications are discussed with regards to the processing of traumatic events.