There seems to be quite a lot of evidence now, that a moderate amount of alcohol consumption (around 1-2 drinks a day) can help protect against Alzheimer’s — though not, a review concluded, vascular dementia or age-related cognitive decline (but the jury’s still out on that one, I think). Moderate alcohol consumption is significantly associated with other factors that help protect against dementia, such as better education, not living alone, and absence of depression, but seems to have an effect on its own account as well.
It must be emphasized that this positive effect is restricted to the ‘right’ level of alcohol consumption. The damage alcohol can do to the brain is only too well established.
The effect doesn’t appear to be restricted to a particular type of alcohol. Having said that, there are components in wine, especially red wine, that have also been associated with lower dementia risk. These components include polyphenols such as epicatechin, catechin and resveratrol.
Benefits may not apply to everyone however. One study found that carriers of the Alzheimer’s gene, APOe4, were more likely to develop dementia if they drank any alcohol — it was only non-carriers that showed a benefit of moderate drinking. Another large study found that the benefits of moderate drinking only applied to those who had no cognitive impairment. For those with mild cognitive impairment, drinking speeded up the rate of decline. Another, large long-running, study found that, although non-smokers who consumed moderate amounts of alcohol were less likely to have a stroke than non-drinkers, this didn’t apply to smokers.
These individual variations may explain the inconsistency in previous studies regarding the relationship between light to moderate drinking and age-related cognitive impairment.
The story of alcohol and the brain is clearly a complex one, not easily disentangled. One large, long-running study, for example, found an association between alcohol and brain atrophy even at moderate levels of consumption.