New peer-reviewed research shows that light alcohol consumption, less than two drinks per day, may be linked to a lower risk of dementia. The same research shows that more than two drinks per day can lead to a higher risk of dementia.
Of course, drinking does have other positive and negative effects on health, like increasing the overall risk of cancer, but this study focuses exclusively on dementia.
As I usually do, I will critique the study, providing you with its results and my analysis of the research and its results.
What are dementia and Alzheimer’s disease?
Before I proceed, it’s important to describe what are dementia and Alzheimer’s disease (AD). Both are chronic neurodegenerative diseases that usually start slowly and worsen over time. AD accounts for 60-70% of dementia cases, even though the terms are sometimes conflated. To be clear, Alzheimer’s disease is a form of dementia.
Amyloid plaques, phosphorylated tau tangles, and neurofibrillary tangles are generally easily visible pathologies that can be observed by microscopic analysis of brain tissue from autopsies of those potentially afflicted by AD. These plaques and tangles seem to have an effect on nerve functioning. Despite these observations, the precise pathophysiology, or development, of the disease is not known.
Of course, dementia includes these pathologies, but because it is a broader term, it includes other types of neurological conditions that are not related to AD.
The causes of AD are unknown (notice how much we do not know about this disease). However, it is speculated that it is mostly genetically related, with a large number of genes that underlie this relationship. Despite the internet tropes, there is no rigorous evidence that aluminum causes AD – I really wish this belief went away fast.
And since we have no clear understanding of the etiology and pathophysiology of AD, there really are no treatments available today for the disease, though some drugs target the amyloid plaques but have not been shown to actually change the outcomes of AD.
There are a couple of medications that help manage some of the symptoms of the disease, but they are certainly not cures. Several drugs at the very earliest stages of development may hold out hope to actually treat the underlying disease.
One more thing that needs to be made clear. There are no biological tests for Alzheimer’s disease — usually, you can only find the amyloid plaques and other pathologies in post-mortem autopsies. Unfortunately. in the absence of an autopsy, clinical diagnoses of AD are “possible” or “probable”, based on other findings, such as memory tests and other methods.
Dementia and alcohol paper
In a paper published on 1 February 2023 in JAMA Network Open, by lead author Keun Hye Jeon, MD, assistant professor of family medicine at Cha Gumi Medical Center at Cha University, Gumi, Korea, and colleagues analyzed data from nearly four million individuals aged 40 years and older in the Korean National Health Insurance Service who completed questionnaires and underwent physical exams in 2009 and 2011.
Study participants completed questionnaires on their drinking habits and were assigned to one of five groups according to changes in alcohol consumption during the study period. The five groups were:
- Sustained non-drinkers
- Those who stopped drinking (described as quitters)
- Those who reduced their consumption of alcohol but did not stop drinking (reducers)
- Those who maintained the same level of consumption (sustainers)
- Those who increased their level of consumption (increasers).
For some background, a standard drink in the US contains 14 g of alcohol. For the purposes of this study, the researchers defined mild drinking as less than 15 g alcohol/day or about one drink; moderate drinking was defined as 15–29.9 g/d, or one to two drinks per day; and heavy drinking as ≥30 g/d, or three or more drinks per day.
At baseline, 54.8% of participants were nondrinkers, 26.7% were mild drinkers, 11.0% were moderate drinkers, and 7.5% were heavy drinkers.
Now that all of the definitions are out of the way, let’s get to their key results:
- From 2009 to 2011, 24.2% of mild drinkers, 8.4% of moderate drinkers, and 7.6% of heavy drinkers became quitters. In the same period, 13.9% of nondrinkers, 16.1% of mild drinkers, and 17.4% of moderate drinkers increased their drinking levels.
- After a mean follow-up of 6.3 years, 2.5% of participants were diagnosed with dementia, 2.0% with Alzheimer’s disease, and 0.3% with vascular dementia.
- Compared to consistently not drinking, mild alcohol consumption was associated with a 21% decreased risk for dementia.
- Moderate alcohol consumption was associated with a 17% reduced risk.
- Heavy drinking was linked to an 8% increased risk of dementia.
- In a surprising result, non-drinkers who became mild drinkers (defined above as increases) had a 7% decrease in dementia and an 8% decrease in Alzheimer’s disease compared to sustained mild drinkers.
What does this all mean?
The whole research field of alcohol consumption and dementia (or Alzheimer’s disease) is quite confusing and murky. For example, there is research that indicates heavy alcohol use may triple the risk of dementia. And as I mentioned above, even light alcohol use can greatly increase your risk of many chronic diseases, like cancer.
And as I mention with these types of studies, they are hard to be comfortable with their study design. It relies upon self-reporting of drinking (and I have a suspicion that drinking levels will be under-reported) which may not be very accurate.
I also have an issue with confounders, that is, variables that might create a spurious relationship between drinking and increasing or decreasing the risk of dementia. For example, smoking might be a confounder, it could be higher in those who drink heavily, and you won’t be able to tell if drinking or smoking (or both) are linked to a higher risk of dementia.
Lastly, this study is not demographically broad, as it only includes South Koreans. There may be differences in outcomes between a narrow demographic group, like in this study, compared to a study that goes across much broader demographic groups such as might be found in one that includes participants in a large number of countries or ethnic groups.
For this study, I can only give it two out of five stars. It’s interesting showing a link between drinking and dementia, but I’m not sold on the results. I buy into the heavy drinking link to dementia because that’s been shown in a number of other studies.
Overall, I think even light drinking has so many negative health consequences (don’t buy into one-off studies that are refuted by other ones) that even if there was a benefit of moderate drinking in reducing the risk of dementia, I probably would weigh it against other health risks.
Citations
- Jeon KH, Han K, Jeong SM, Park J, Yoo JE, Yoo J, Lee J, Kim S, Shin DW. Changes in Alcohol Consumption and Risk of Dementia in a Nationwide Cohort in South Korea. JAMA Netw Open. 2023 Feb 1;6(2):e2254771. doi: 10.1001/jamanetworkopen.2022.54771. PMID: 36745453.
