Interactive Influence of Alcohol and Stress on Learning and Intrusive Memories: A Preliminary Report

Abstract

Traumatic events, such as sexual/physical assaults and motor vehicle accidents, frequently involve individuals who are under the influence of alcohol. Research suggests that peri-traumatic alcohol ingestion can increase the risk for PTSD symptomatology, particularly intrusive memories. However, no studies have examined the impact of alcohol on what participants remember about a laboratory-controlled stressful event or the number of intrusive memories that result from such an event. Thus, in the present study, participants ingested ethanol or a placebo and were then exposed to a modified version of the Trier Social Stress Test (TSST) or the friendly-TSST (f-TSST). The TSST required participants to deliver a ten-minute speech in front of two lab panel members as part of a mock job interview; the f-TSST required participants to casually converse with panel members about their interests and hobbies. In both conditions, the panel members interacted with (central) or did not interact with (peripheral) several objects sitting on a desk in front of them. The next day, participants’ memory for the objects that were present on Day 1 was assessed with recall and recognition tests. We also quantified participants’ intrusive memories on Days 2, 4, 6, and 8. Participants exposed to the TSST exhibited greater recall of central and peripheral objects and fewer falsely recalled objects than participants exposed to the f-TSST. Importantly, on Days 2 and 4, participants exposed to the TSST reported a greater number of intrusive memories related to the speech task, and this effect was augmented by alcohol. Our findings suggest that memory for a stressful event is enhanced, relative to memory for a non-stressful event, and that alcohol may increase the development of intrusive memories related to a stressful experience.