KEY POINTS:
A glass or two of wine a day may just make the mind a little bit sharper, but drinking to forget could make things worse.
A new Auckland University study found moderate levels of alcohol consumption could enhance memory.
But high levels of alcohol decrease the ability of new brain cells to develop and mature, and impair memory - except in moments of heightened emotion, when memory is increased.
"Low levels of alcohol promoted neutral memories, such as remembering objects," said researcher Dr Maggie Kalev.
"However, contrary to popular belief, we also found that excessive levels of alcohol enhanced memories of highly emotional stimuli, meaning the concept of 'drinking to forget' is unlikely to be true. Our work suggests that heavy drinking actually reinforces negative memories."
The results of the study by Dr Kalev and Professor Matthew During are published in the latest Journal of Neuroscience.
Professor During said they were not entirely sure how moderate levels of alcohol aided in improving memory, but believed it was through its interaction with NMDA receptors in the brain.
"Alcohol interacts with that particular protein in the brain and disrupts and alters its function in a way that actually induces a little bit of stress in the brain."
It was a process similar to the strengthening of muscles by stressing them through exercise, he said.
But too much alcohol only enhanced negative memories, such as those involving some emotional trauma. Professor During believes this to be a control mechanism.
"Evolution's been going on for so long, why hasn't evolution made our memories better? It's probably because there's a little negative component to having too good a memory - you just imagine [remembering] every time you nearly got run over or had an accident happen outside, you'd get paranoid. It'd be too terrifying so you shut down and you can't function in society."
High levels of alcohol disrupts the pattern by influencing additional parts of the brain.
Professor During said a moderate level of alcohol varies among individuals.
"We're basically saying the legal driving limit is the threshold."
The study, conducted on rats, holds an important key for unlocking future treatments for memory disorders such as Alzheimer's and other dementias, and improve recovery prospects for those who have had a stroke.
Dr Kalev and Professor During are now looking at therapies such as antibodies. "Pathways by which memory is laid down are unclear, but the NMDA receptor is critical in this process," she said.
