While many studies have shown that excessive alcohol intake is associated with cognitive impairment and increased risk of dementia, most cohort studies have shown that the risks of these outcomes are lower among light-to-moderate drinkers than among abstainers. The authors of this paper conducted a scoping review on this topic, based on a systematic search of systematic reviews published from January 2000 to October 2017. A total of 28 systematic reviews were identified relating alcohol intake at various time periods to incidence of cognitive impairment/dementia, specific brain functions, or induced dementias. The authors report that light to moderate alcohol use in middle to late adulthood was associated with a decreased risk of cognitive impairment and dementia, but heavy alcohol use was associated with changes in brain structures, cognitive impairments, and an increased risk of all types of dementia.
Forum members considered this to be a well-done analysis, but were concerned that the focus was only on the potentially adverse effects of heavy drinking, with little regard or discussion of the findings of protection against such cognitive outcomes among light or moderate drinkers. Forum members point out that there are very many adverse health effects, both for the drinker and for society, resulting from heavy drinking. To them, the most interesting and provocative aspect of this paper was the conclusion of a protective effect against cognitive decline and dementia associated with light-to-moderate alcohol consumption.
Scientific data, including the results of the present systematic analysis, are very consistent in showing that cognitive decline, associated impairments in the functions of daily living, incident dementia, and survival are all associated favorably with light-to-moderate consumption of alcohol in middle age. The reasons and mechanisms that lead to these associations deserve further evaluation. With the increasing ageing of populations throughout the world, cognitive decline and dementia are expected to increase and create serious challenges for health care providers. Insight into ways of preventing or delaying the onset of such cognitive decline (in addition to decreasing the prevalence of heavy alcohol intake, the focus of this paper) could be extremely important in planning for the future.
Reference: Rehm J, Hasan OSM, Black SE, Shield KD, Schwarzinger M. Alcohol use and dementia: a systematic scoping review. Alzheimer’s Research & Therapy 2019; 11: pre-publication.