Alcohol affects the brain in several ways, one of which inhibit contextual memories more than egocentric, viewpoint-specific memories.
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LONDON: People who have a drink or two prior to a traumatic event may suffer from more flashbacks than if they were either sober or drunk, said researchers.
The study may help better understand conditions such as post-traumatic stress disorder (PTSD), given alcohol's frequent involvement in traumas such as sexual attacks and road accidents, according to the team of researchers at University College London (UCL).
"This research gives us an idea of how being under the influence of alcohol might contribute to our wellbeing later on," explained James Bisby, lead author of the study, which was published in Biological Psychiatry.
Masked alcohol with Tabasco sauce
The study involved 48 UCL students who were given either a zero, moderate or high dose of alcohol, the taste of which was masked by Tabasco sauce.
Next each subject performed a virtual reality task designed to examine how an experienced event is stored within memory.
Finally, they were shown a series of horrific scenes from road traffic accidents and asked to record the details of any involuntary flashbacks in the following seven days in an online diary. Moderate dose subjects experienced significantly more flashbacks than both other groups.
Two types of memory
Bisby believes the results are due to alcohol's different effects on two different types of memory.
One type is egocentric, viewpoint dependent memory - "a visual snapshot of the scene in relation to the perceiver," Bisby explains. The second is viewpoint independent, and relies more on contextual information.
The researchers suggest that a moderate amount of alcohol (around three units) inhibits contextual memories, allowing the egocentric, viewpoint-specific memories - such as flashbacks - to emerge more frequently.
Consuming high levels of alcohol however (seven units or more), disrupts both types of memory, so the number of flashbacks decreases.
Difficult to mimic real life trauma
Justin Kenardy, an expert on PTSD from the University of Queensland who was not involved in the research said the study provides us with an "interesting" insight into the condition; "Anything that helps us to understand who does and does not get PTSD following trauma is useful," he said. "It would be useful, although difficult, to see if these relationships hold up in real life."
Bisby acknowledges there are differences between their methodology and real life trauma. "Although the type of methods we use do not create the intense reaction individuals may experience during an actual trauma, they do provide a prospective way to examine individuals' responses within a laboratory environment."
Follow up studies are already in the pipeline for the team at UCL, Bisby added. "We plan to further our findings by looking in greater depth at why alcohol may show this effect and how drinking alcohol following the event may affect our psychological outcome."
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