Acute effects of alcohol on the development of intrusive memories.
BACKGROUND
Post-traumatic stress disorder is characterised by repeated intrusive imagery of the traumatic event. Despite alcohol's impairing effect on memory and frequent involvement in real-life trauma, virtually nothing is known of the interaction between alcohol and trauma memory.


OBJECTIVE
We aimed to investigate the acute alcohol effects on spontaneous memories following a trauma film as well as explicit memory for the film.


METHODS
Utilising an independent-group double-blind design, 48 healthy volunteers were randomly allocated to receive alcohol of 0.4 or 0.8 g/kg or a matched placebo drink. A stressful film was viewed post-drink. Skin conductance was monitored throughout and mood and dissociative symptoms were indexed. Volunteers recorded their spontaneous memories of the film daily in an online diary over the following week. Their explicit memory for both gist and details of the film was tested on day 7.


RESULTS
Intriguingly, an inverted 'U' alcohol dose-response was observed on intrusive memories with a low dose of alcohol increasing memory intrusions while a high dose decreased intrusions. In contrast, explicit memory performance after 7 days showed a linear dose-response effect of alcohol with both recall and recognition decreasing as dose increased.


CONCLUSIONS
These findings highlight a striking differential pattern of alcohol's effects on spontaneous memories as compared with explicit memories. Alcohol's effect on spontaneous memories may reflect a dose-dependent impairment of two separate memory systems integral to the processing of different aspects of a traumatic event.
Bisby
James A
JA
Clinical Psychopharmacology Unit, University College London, Gower Street, London, UK. j.bisby@ucl.ac.uk
Brewin
Chris R
CR
Leitz
Julie R
JR
Valerie Curran
H
H
D000328:Adult; D002492:Central Nervous System Depressants / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D000431:Ethanol / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008568:Memory / Q000187:drug effects*; D011939:Mental Recall / Q000187:drug effects*; D009040:Motion Pictures; D021641:Recognition, Psychology / Q000187:drug effects; D013313:Stress Disorders, Post-Traumatic / Q000503:physiopathology; D013997:Time Factors; D055815:Young Adult
D002492:Central Nervous System Depressants; D000431:Ethanol