Yes, that’s the headline we’ve all been waiting for.
Scientific American reports on a recent study from the Journal of Neuroscience in which researchers fed rats on low (2.5%) or high (5%) ethanol diets and then tested their performance on two memory tasks. The first involved novel object recognition, in which the rats are first exposed to a pair of identical objects and then exposed to one of the familiar objects and one novel object. The percentage of time spent investigating the novel object is considered an index of memory, not entirely unlike looking the looking time tasks that are used with human infants. The second task involved training the rats with a footshock in one of two compartments and then testing the degree to which they avoided this compartment in subsequent testing.
On both tasks, rats consuming the 2.5% ethanol diet performed better. Rats consuming the 5% ethanol diet maintained superior performance on the fear conditioning experiment but performed worse on novel object recognition.
The researchers also tested rats with a dysfunctional copy of the NR1 subunit of the NMDA receptor. In contrast to wild type animals, the mutants did not exhibit increased memory function in in response to moderate ethanol consumption. This suggests that alcohol’s beneficial effects are mediated through NMDA receptors, akin to the beneficial effects of fasting.
The authors stress that 5% ethanol had neurotoxic effects on the rats that consumed it, including reduced neurogenesis and NR1 expression. They propose an inverted U function for alcohol’s facilitatory effects on cognition, as diagrammed below:
So, like I always say when a study like this comes out, everything is good in moderation.