Is abstinence a risk factor for dementia?

In a large sample of older adults (> 60 years) from low- and middle-income countries, the current study found that abstaining from alcohol is associated with an increased risk of dementia.

In recent decades, the global prevalence of dementia has almost tripled, from 20.2 million in 1990 to 57.4 million in 2019. By 2050, the number of individuals living with dementia is projected to increase to 152 million.

Without having a treatment for dementia, reducing the risk factors is fundamental for preventing the onset of dementia. Excessive or harmful use of alcoholic beverages is regarded as one of the key modifiable risk factors for dementia because of the neuro-toxic effects of ethanol on the brain.

In observational studies, heavy alcohol use has been found to increase the risk for dementia, but some studies also have shown that excessive alcohol use seemed to be unrelated to dementia risk. In contrast, light to moderate consumption of alcoholic beverages appears to reduce the dementia risk when compared to abstinence and the alcohol-dementia relationship seems to be J-shaped.

In these observational studies, standardization of alcohol intake and the definitions of light, moderate and heavy varied widely and former drinkers and life-time abstainers were mixed in the reference/control group.

The current study intends to address the limitations listed above, harmonise the data from 15 prospective studies that were carried out in six continents and combine international findings on the alcohol-dementia association.

Participants included 24 478 community dwelling individuals without a history of dementia at baseline and at least one follow-up dementia assessment. The main outcome measure was dementia from any cause as determined by clinical interview. The mean age across the studies was 71.8. 54% of all participants were current drinkers and during the follow-up period 2124 cases of dementia were diagnosed. The results showed that compared to abstainers the risk for dementia was lower in occasional (<1.3 g of alcohol/day), light-moderate (1.3-24.9 g/day) and moderate-heavy drinkers (25-44.9 g/day). There was no evidence of differences between life-time abstainers and former drinkers with regards to dementia risk. In a dose-response analysis, drinking up to 40 g of alcohol/day was associated with a lower risk of dementia when compared with life-time abstainers.

The researchers concluded that they found consistent evidence to suggest that abstaining from alcoholic beverages was associated with an increased risk for dementia in this large international sample of older adults over the age of 60. However, advising those who currently abstain to initiate drinking is not advised. Among current drinkers, alcohol use did not appear to be a consistent risk factor for dementia, even though this relationship varied across continents and could not be examined among heavier drinkers.

Mewton, L, Visontay, R, Hoy, N, Lipnicki, DM, Sunderland, M, Lipton, RB, et al. The relationship between alcohol use and dementia in adults aged more than 60 years: a combined analysis of prospective, individual-participant data from 15 international studies. Addiction. 2022. doi.org/10.1111/add.16035

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