Propranolol's effects on the consolidation and reconsolidation of long-term emotional memory in healthy participants: a meta-analysis.
Level 1 - systematic review of randomized trials
Meta-analysis of randomized, double-blind controlled experimental trials
PubMed 23182304 · doi:10.1503/jpn.120111
What was done
Authors conducted a systematic review and meta-analysis of randomized, double-blind, placebo-controlled experiments published between 1995 and 2012 (searching PsycInfo, PubMed, Web of Science, Cochrane Central, PILOTS, Google Scholar, and clinicaltrials.org). Eligible studies evaluated the effect of the beta-blocker propranolol on long-term emotional memory consolidation or reconsolidation in healthy adults. Ten consolidation experiments (n = 259) and 8 reconsolidation experiments (n = 308) met inclusion criteria, and effect sizes were calculated as Hedges g using random-effects models.
What was found
Propranolol administered prior to memory consolidation significantly reduced subsequent recall for negatively valenced stories, pictures, and word lists relative to placebo (Hedges g = 0.44, 95% CI 0.14 to 0.74). Propranolol administered prior to reconsolidation also significantly reduced subsequent recall for negatively valenced emotional words and cue-elicited fear responses (Hedges g = 0.56, 95% CI 0.13 to 1.00).
Why it matters
This provides quantitative evidence that pharmacological beta-adrenergic blockade can disrupt both the formation and reconsolidation of emotional memories in humans. It supports the theoretical rationale for testing reconsolidation-blocking interventions in event-related psychiatric disorders such as PTSD.
Limits
The total number of eligible studies and sample sizes per experiment were small. Most participants were healthy young adults exposed to standardized laboratory stimuli rather than real-world traumatic memories, limiting ecological validity and direct translation to clinical populations.
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