Disclosures: Kivimäki reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
September 18, 2020
2 min read

People who lose consciousness due to alcohol at greater risk for dementia

Disclosures: Kivimäki reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
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Alcohol-induced loss of consciousness appeared associated with a subsequent increase in dementia risk, according to results of a multicohort study published in JAMA Network Open.

“[Although] the potential for clinical alcohol disorders to affect dementia appears clear, the role of overall alcohol intake in the development of dementia in the general population is uncertain,” Mika Kivimäki, PhD, of the department of epidemiology and public health at University College London, and colleagues wrote. “Meta-analyses of population-based studies suggest an elevated incidence of dementia for individuals with heavy compared with moderate alcohol consumption, although this observation is not universal and has not been replicated in mendelian randomization studies using genetic variants as proxies for alcohol consumption. A further limitation in most research on the association between alcohol use and dementia is the lack of consideration of drinking patterns.”

silhouette of man with alcohol bottles
Source: Adobe Stock

In the current study, Kivimäki and colleagues sought to determine the effects of overall alcohol consumption and alcohol-induced loss of consciousness on future dementia risk. They analyzed data of 131,415 participants in seven cohort studies conducted in the U.K., France, Sweden and Finland. Participants were aged 18 to 77 years, were free of diagnosed dementia and reported alcohol consumption at baseline.

The investigators examined dementia for a mean follow-up of 14.4 years. Exposures included self-reported overall consumption and alcohol-induced loss of consumption. Heavy overall consumption consisted of greater than 14 units, according to the U.K. definition, and greater than 21 units, according to the U.S. definition, per week. The main outcome was dementia and alcohol-related disorders to 2016, which the researchers ascertained using linked electronic health records.

Results showed 0.8% of participants developed dementia. The HR was 1.16 (95% CI, 0.98-1.37) for consumption of more than 14 vs. one to 14 units of alcohol weekly and 1.22 (95% CI, 1.01-1.48) for consumption of more than 21 vs. one to 21 units weekly, after adjusting for potential confounders.

Among 96,591 participants with data on loss of consciousness, 10.4% reported having done so because of alcohol consumption in the past 12 months. Kivimäki and colleagues observed an association between loss of consciousness and dementia among men (HR = 2.86; 95% CI, 1.77-4.63) and women (HR = 2.09; 95% CI, 1.34-3.25) during the first decade of follow-up (HR = 2.72; 95% CI, 1.78-4.15) and after excluding this first decade (HR = 1.86; 95% CI, 1.16-2.99). They also noted associations for early-onset (HR = 2.21; 95% CI, 1.46-3.34) and late-onset (HR = 2.25; 95% CI, 1.38-3.66) dementia, Alzheimer’s disease (HR = 1.98; 95% CI, 1,28-3.07) and dementia with features of atherosclerotic cardiovascular disease (HR = 4.18; 95% CI, 1.86-9.37). According to the researchers, 14 other conditions related to alcohol did not explain the association.

The HR was twice as high among participants who reported having lost consciousness vs. those who moderately consumed alcohol and had not lost consciousness. This risk was greater whether the mean weekly consumption was moderate (HR = 2.19; 95% CI, 1.42-3.37) or heavy (HR = 2.36; 95% CI, 1.57-3.54).

“This increased risk suggests that the drinking pattern is important vs. just the overall weekly quantity consumed,” the researchers wrote. “These findings add to the knowledge base about the implications of alcohol misuse on the brain.”