Passing Out From Alcohol Tied to a Doubling of Dementia Risk

Megan Brooks

September 17, 2020

People who drink alcohol until they pass out may have more than a hangover to contend with.

In a study of more than 130,000 people, alcohol-induced loss of consciousness was associated with a doubling of the risk for subsequent dementia, regardless of overall alcohol consumption.

"Policy documents and guidelines on dementia prevention emphasize the importance of keeping overall alcohol consumption at moderate levels," first author Mika Kivimaki, PhD, Department of Epidemiology, University College London, United Kingdom, told Medscape Medical News.

"Our study suggests that it is also important to consider drinking patterns, because we found that binge drinking may be a long-term dementia risk factor even if a person usually drinks moderately," said Kivimaki.

The study was published online September 9 in JAMA Network Open.

Robust Association

The researchers examined data from seven cohort studies that measured alcohol intake in 131,415 adults (61% women) from the United Kingdom, France, Sweden, and Finland.

Most (79%) were self-reported moderate drinkers (1 to 14 units/wk); fewer than 1% were were heavy drinkers (>14 units/wk). Heavy drinking was more common among men and smokers.

At baseline, participants were 43 years old on average and were free of dementia. During an average follow-up period of more than 14 years, 1081 (0.8%) developed dementia (mean age, 70.7 years).

After controlling for overall alcohol intake, the investigators found that in comparison with those who had not passed out after drinking in the prior year, dementia incidence was increased among those who lost consciousness once (hazard ratio [HR], 2.10; 95% CI, 1.42 – 3.11) or more than once (HR, 2.19; 95% CI, 1.40 – 3.42).

Likewise, compared with those who did not report losing consciousness and who were moderate drinkers, those who did report losing consciousness were at twofold increased risk for dementia, irrespective of whether their average consumption was moderate (HR, 2.19; 95% CI, 1.42 – 3.37) or heavy (HR, 2.36; 95% CI, 1.57 – 3.54).

"As well as all-cause dementia, this association was seen for early- and late-onset dementia, Alzheimer disease, and dementia with features of atherosclerotic cardiovascular disease," the authors report.

"The association was robust to adjustment for other lifestyle factors, hypertension, and diabetes, evident in men and women, noted in older and younger participants, and observed in those with an otherwise healthy or unhealthy lifestyle," they note.

Overall, the results implicate neurotoxicity of losing consciousness as an explanation for the association with dementia, they add.

"We need to consider both overall consumption of alcohol over a longer period of time and a person's drinking pattern. High overall consumption certainly increases risk of dementia. However, those who drink to the point of passing out are also at increased risk of dementia even if their average consumption is moderate," Kivimaki told Medscape Medical News.

The study had no commercial funding. Kivimaki has disclosed no relevant financial relationships.

JAMA Netw Open. Published September 9, 2020. Full text

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