The latest critique from The ISFAR considers research into the effects of alcohol on brain structure

The latest critique from The ISFAR considers research into the effects of alcohol on brain structure

While numerous prospective epidemiologic studies have provided evidence that light-to-moderate amounts of alcohol reduce the risk of dementia and heavy drinking increases the risk, there are few studies on the effects of alcohol on brain structure assessed by magnetic resonance imaging (MRI).

A recent study comprised a cross-sectional evaluation between reported alcohol intake and MRI-assessed brain structure among 589 multi-ethnic community residents of New York. Total brain volume (TBV), white matter hyperintensity volume (WMHV), and presence of infarcts were derived from MRI scans when subjects were, on average, 80 years of age.

A key finding of this analysis is that, in comparison with non-drinkers, light-to-moderate alcohol intake (up to an average of one drink per day for women or two drinks per day for men, which was reported in 31% of their subjects) was associated with larger TBV (ie, less brain atrophy). The effect was primarily among consumers of wine rather than of beer or liquor. Significant associations were not found for alcohol or for specific beverages for other measures of brain structure (WMHV or presence of infarcts).

ISFAR forum reviewers considered this to be an appropriate analysis that was able to consider many of the potential confounders of such an association.

On the other hand, it was not a large study and was based on a cross-sectional analysis; thus, it cannot be used to judge causation - it is possible, for example, that people with larger brains to begin with were more likely to consume wine or total alcohol, rather than their alcohol intake increasing their brain size.

Data from many previous studies has shown that moderate alcohol intake lowers the risk of developing clinical signs of cognitive decline and of dementia. Such a finding has led forum members to be of the opinion that instructing the elderly to refrain from light-to-moderate amounts of alcohol may not be wise.

Although, prospective studies may show that the decrease in the risk ratio for dementia (comparing drinking with abstainers) tends to be less among the elderly than among middle-aged subjects, the absolute risk of dementia increases markedly with age. Thus, any intervention that lowers the risk of cognitive impairment will have a much greater impact in older people as compared with younger people.

Given the inconsistences in previous reports on the effects of alcohol on brain structure, we must conclude that, while this study suggests there might be a beneficial association between alcohol (especially wine intake) and brain size, such a relation is not definitive. An inverse relation between moderate drinking and clinical evidence of dementia, however, has received support from a large number of prospective epidemiologic studies; it may be a better association for us to use when advising the elderly regarding alcohol consumption.

Overall, scientific data indicates that, for elderly subjects without contraindications to alcohol, small amounts of wine or other alcoholic beverage consumed regularly may reduce the risk of dementia and other diseases of ageing.

As stated by Michel de Montaigne many centuries ago: "Drinking is the almost last pleasure that the years steal from us."

To read the full critique, click here.

These critiques are published with the permission of The ISFAR.