Heavy drinking has been identified as a preventable risk factor for dementia. Observational studies have drawn conflicting conclusions regarding the potential benefit or harm to the brain of low to moderate alcohol consumption. Differences in lifestyle factors between drinkers and non-drinkers have made it difficult to draw clear conclusions specifically related to alcohol. Imaging studies suggest that negative brain changes start taking place at moderate levels of consumption, in people with normal cognition. Updated international guidelines have lowered the threshold for levels of alcohol consumption that are considered low risk.
Dozens of observational studies and many meta-analyses and systematic reviews report inconsistent conclusions on whether moderate levels of alcohol consumption prevent or promote cognitive decline. Our search identified:
• Multiple meta-analyses and systematic reviews on observational studies • 0 randomized controlled trials • Multiple observational studies
Although many observational studies have examined whether drinking low to moderate amounts of alcohol is associated with a reduced risk of developing Alzheimer’s disease, vascular dementia, or age-related cognitive decline, they reached no consensus [1; 2; 3; 4; 5; 6]. Most of these studies suffer from a number of confounding factors, particularly with respect to the characteristics of the non-drinking comparator population. In general, a large percentage of non-drinkers have a higher baseline risk for dementia due to sex, socioeconomic status, lifestyle factors, education, dietary habits, and/or health status [7]. Wine drinkers, as opposed to beer or spirit drinkers, have been more likely to show reduced dementia risk, which some have attributed to potential cardiovascular effects. However, individuals who regularly have a glass of wine tend to also have high socioeconomic status and engage in other brain healthy behaviors [6]. In the short-term, alcohol is well-known to impair cognitive function, and heavy drinking is an established risk factor for cognitive decline [8]. Recent well-designed studies that track people over time have found that even moderate levels of alcohol consumption, such as one to two drinks per day, is associated with adverse brain changes consistent with accelerated brain aging [9; 10; 11; 12].
APOE4 has been found to impact a variety of lifestyle-related dementia risk factors. APOE4 carriers who drink high amounts of alcohol appear to be at greater risk for dementia than APOE4 carriers who drink rarely or never [13; 14; 15]. APOE4 carriers may also be at greater risk from the brain health side effects of moderate alcohol consumption than those who do not have the APOE4 variant [16; 17; 18].
There is no evidence that alcohol use can slow the progression of cognitive decline in patients with Alzheimer's disease or dementia. Given that alcohol can acutely impair cognitive function and interacts dangerously with many medications, patients with dementia should probably abstain.
According to the World Health Organization, there is no safe level of alcohol consumption [19]. Heavy drinking is associated with a number of potential side effects including high blood pressure, obesity, stroke, cardiovascular disease, liver disease, certain forms of cancer, and Alzheimer's disease [4; 20; 21]. However, individual susceptibility to the negative effects of alcohol varies across people such that it is not possible to identify a uniformly safe level of consumption. In studies looking at brain changes, drinking the equivalent of two drinks or less per week was not associated with harm [11], and this level is also considered low risk in the 2023 Canadian guidelines [22].
NOTE: This is not a comprehensive safety evaluation or complete list of potentially harmful drug interactions. It is important to discuss safety issues with your physician before taking any new supplement or medication.
The guidelines regarding alcohol consumption vary in different countries. In the United States, moderate alcohol intake is defined as one drink per day for women and two drinks per day for men [23]. These are similar to the guidelines in Europe [24] but exceeds the Canadian recommended guidelines for low-risk consumption of no more than one to two drinks per week [22]. A standard drink in the United states is equivalent to roughly 14 grams of alcohol, which is found in 12 ounces of regular beer (~5% alcohol), 5 ounces of wine (~12% alcohol), and about 1.5 ounces of distilled spirits (~40% alcohol). Since high levels of alcohol are acutely toxic to the brain, the safest way to consume it is in small doses over an extended period of time, such as no more than one glass of wine with dinner consumed over the course of an hour or two.
General information on how to define different types of drinking can be found at the Centers for Disease Control, and the National Institute on Alcohol Abuse and Alcoholism.
Information on alcohol’s effects on the body can be found at the National Institute on Alcohol Abuse and Alcoholism.
Check for drug-alcohol and supplement-alcohol interactions on Drugs.com.