The idea that drinking a glass of wine daily helps avoid heart disease is common knowledge, but a new study cited by Scientific American suggests moderate alcohol consumption also helps memory. In the study, two researchers from the University of Auckland in New Zealand and The Ohio State University College of Medicine experimented with two groups of rats—one normal group and one group that was genetically modified with enhanced NMDA receptors, which are critical for memory. The rats were fed diets made up of 0%, 2.5%, and 5% ethanol.
The rats stayed on these diets for eight weeks; behavioral testing to assess cognitive function began after four weeks. One test involved novel object recognition, where rats were placed in a cage with two small objects inside multiple times over a two-day period. Then, one object was swapped for a new toy and rats were scored based on how quickly they explored the unfamiliar piece. In a second paradigm, rats were trained to expect a shock when they crossed from a white compartment to a black one inside a cage; a day after training, the rats were put back in the cage to see if they remembered that the black side was dangerous.
Among the normal rats, the animals that consumed moderate amounts of alcohol fared better on both tests compared with the teetotalers. Rats on a heavy alcohol diet did not do well on object recognition (and, in fact, showed signs of neurotoxicity), but they performed better than their normal brethren on the emotional memory task.
According to one of the researchers, the 2.5% ethanol diet fed to the rats was equivalent in human terms to "a level of consumption that does not exceed [the] legal driving limit." Depending on a person's size, metabolism, or genetic background, "this may be approximately one to two drinks per day for some people or two to three for others."