- Largest study of its kind finds alcohol use biggest risk factor for dementia
- Alcohol and dementia
- How can alcohol damage the brain?
- Is moderate alcohol consumption safe for the brain?
- What should I take away from this research?
- The Surprising Truth About How Alcohol Affects Your Dementia Risk
- expert reaction to study looking at alcohol and risk of dementia and cognitive decline
Largest study of its kind finds alcohol use biggest risk factor for dementia
Alcohol use disorders are the most important preventable risk factors for the onset of all types of dementia, especially early-onset dementia. This according to a nationwide observational study, published in The Lancet Public Health journal, of over one million adults diagnosed with dementia in France.
This study looked specifically at the effect of alcohol use disorders, and included people who had been diagnosed with mental and behavioural disorders or chronic diseases that were attributable to chronic harmful use of alcohol.
Of the 57,000 cases of early-onset dementia (before the age of 65), the majority (57%) were related to chronic heavy drinking.
The World Health Organization (WHO) defines chronic heavy drinking as consuming more than 60 grams pure alcohol on average per day for men (4-5 Canadian standard drinks) and 40 grams (about 3 standard drinks) per day for women.
As a result of the strong association found in this study, the authors suggest that screening, brief interventions for heavy drinking, and treatment for alcohol use disorders should be implemented to reduce the alcohol-attributable burden of dementia.
“The findings indicate that heavy drinking and alcohol use disorders are the most important risk factors for dementia, and especially important for those types of dementia which start before age 65, and which lead to premature deaths,” says study co-author and Director of the CAMH Institute for Mental Health Policy Research Dr. Jürgen Rehm. “Alcohol-induced brain damage and dementia are preventable, and known-effective preventive and policy measures can make a dent into premature dementia deaths.”
Dr. Rehm points out that on average, alcohol use disorders shorten life expectancy by more than 20 years, and dementia is one of the leading causes of death for these people.
For early-onset dementia, there was a significant gender split. While the overall majority of dementia patients were women, almost two-thirds of all early-onset dementia patients (64.9%) were men.
Alcohol use disorders were also associated with all other independent risk factors for dementia onset, such as tobacco smoking, high blood pressure, diabetes, lower education, depression, and hearing loss, among modifiable risk factors. It suggests that alcohol use disorders may contribute in many ways to the risk of dementia.
“As a geriatric psychiatrist, I frequently see the effects of alcohol use disorder on dementia, when unfortunately alcohol treatment interventions may be too late to improve cognition,” says CAMH Vice-President of Research Dr. Bruce Pollock.
“Screening for and reduction of problem drinking, and treatment for alcohol use disorders need to start much earlier in primary care.” The authors also noted that only the most severe cases of alcohol use disorder — ones involving hospitalization — were included in the study.
This could mean that, because of ongoing stigma regarding the reporting of alcohol-use disorders, the association between chronic heavy drinking and dementia may be even stronger.
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Alcohol and dementia
Excessive alcohol consumption over a lengthy time period can lead to brain damage, and may increase your risk of developing dementia. However, drinking alcohol in moderation has not been conclusively linked to an increased dementia risk, nor has it been shown to offer significant protection against developing dementia.
As such, people who do not currently drink alcohol should not be encouraged to start as a way to reduce dementia risk.
Conversely, those who drink alcohol within the recommended guidelines are not advised to stop on the grounds of reducing the risk of dementia, although cutting back on alcohol consumption may bring other health benefits.
Two reviews of the available evidence conducted by Alzheimer's Disease International and the National Institute for Health and Care Excellence (NICE) scrutinised multiple research studies of alcohol consumption and the development of dementia.
Both reviews used a systematic approach, that is one in which researchers evaluate the conclusions made in multiple previously published research studies.
While this may sound a re-run of old data, it is a powerful approach that allows us to make stronger conclusions on a given topic. If multiple studies using varied methods and studying different groups of people come up with the same conclusion, then we can be more certain of the conclusion for the whole population.
These reviews found that individuals who drank heavily or engaged in binge drinking – where a person consumes a large quantity of alcohol in a short time period – were more ly to develop Alzheimer's disease or any other form of dementia than those who engaged in moderate alcohol consumption (see below for definition).
The research evaluated by NICE focused on large populations of hundreds or even thousands of people, starting in mid-life (age 40-64) and tracked them for over five years, sometimes well in to old age, to trace how long term behavioural patterns could impact dementia risk.
How can alcohol damage the brain?
Heavy alcohol consumption over a long period of time can lead to brain damage. People who drink heavily over a long period of time are more ly to have a reduced volume of the brain's white matter, which helps to transmit signals between different brain regions. This can lead to issues with the way the brain functions.
Long-term heavy alcohol consumption can also result in a lack of vitamin thiamine B1 and Korsakoff's Syndrome, a memory disorder affecting short term memory.
Alcohol-related brain damage (ARBD) is a brain disorder. which covers several different conditions including Wernicke-Korsakoff syndrome and alcoholic dementia, caused by regularly drinking too much alcohol over several years.
These reviews typically defined moderate alcohol consumption as 1-14 units of alcohol per week for women and 1-21 units a week for men.
NHS guidelines published in 2016 state that both men and women should limit their intake to 14 units a week.
A unit is dependent on the amount of pure alcohol in a given volume and can be calculated for specific drinks here. According to the NHS, a basic guideline for units of alcohol is as follows:
- A typical glass (175mL) of (12%) wine: 2 units
- A pint of lower (3.6%) alcohol beer or cider: 2 units
- A pint of higher (5.2%) alcohol beer or cider: 3 units
- A single shot (25mL) of spirits such as whisky, gin or vodka (40%): 1 unit
Is moderate alcohol consumption safe for the brain?
Some research has indicated that individuals who drank in moderation were less ly to develop Alzheimer's disease or any other form of dementia than those who consumed zero alcohol.
Some protective effects of alcohol have been seen on the brain, such as reduced thickness of blood (called plasma viscosity) and increased levels of healthy cholesterol (also known as HDL cholesterol) in the body. Both of these effects have been suggested to help lower the risk of developing dementia.
However, the evidence produced by studies that link moderate alcohol consumption with a lower lihood of Alzheimer's disease does have some flaws. For example, many of these studies classified 'non-drinkers' as both people who have given up alcohol consumption due to health reasons (such as previous alcoholics) and lifetime non-drinkers.
These two subsets of people are actually quite different as people who have given up drinking for health reasons may have already had alcohol-induced brain damage, so are more ly to be similar to people in the heavy-drinking category than lifetime non-drinkers.
Therefore the mixing of these distinct populations into one study group may have skewed the results and lead to conclusions which overstate the potential risk of not drinking alcohol to developing Alzheimer's and dementia.
It is important that future research differentiates between lifetime non-drinkers and individuals who have given up drinking for health reasons to clarify these findings.
One such study has shown no evidence for a protective effect of moderate alcohol consumption on the development of dementia although we will need to see the results of further studies that make this distinction before we can fully understand this relationship.
What should I take away from this research?
The link between alcohol and dementia (or lack thereof) in non-drinkers however is not fully understood and individuals who do not currently drink alcohol should not start as a method of protection against the development of dementia.
From the evidence collected to date, it is not possible to determine what effect drinking within the NHS recommended alcohol guidelines has on a person's risk of dementia.
Guidelines published by NICE in 2015 recommend that alcohol consumption be reduced as much as possible, particularly in mid-life, to minimize the risk of developing other age-related conditions such as frailty.
Current evidence indicates that adopting a healthy lifestyle throughout your life is the best way to reduce risk of dementia and other long-term health problems.
This includes drinking in moderation but also other factors such as not smoking, taking plenty of physical exercise and eating a healthy, balanced diet.
The Surprising Truth About How Alcohol Affects Your Dementia Risk
Alcohol drinks are frequently cited in medical news, both for their benefits as well as for the harm that alcohol misuse and addiction causes. So, what do those reports say about your mind on alcohol? Does alcohol impact the functioning of your brain? Does it affect your risk of developing Alzheimer's disease?
In a word, yes. But how? The answer depends on several factors, but two of the more researched factors include the amount of alcohol consumed and whether someone is an APOE ε4 gene carrier.
Multiple research and observational studies have demonstrated that people who drink high amounts of alcohol are at an increased risk of developing dementia. Alcohol-related brain damage may account for approximately 10% of all dementia cases.
Imaging tests of the brains of high alcohol drinkers demonstrate atrophy (brain shrinkage), loss of white matter, decreased neurons and other changes similar to the brains of people with Alzheimer's disease.
Cognitive impairments among excessive alcohol drinkers include:
These cognitive impairments may develop over time, but alcohol can also cause immediate memory loss, known as blackouts.
According to one study conducted on the risk factors for younger-onset dementia, alcohol intoxication as a late teenager is one of the highest predictors of men who will develop it. Additionally, a second study found that 57% of young-onset dementia was related to chronic heavy alcohol use.
Moderate alcohol drinking is classified as drinking one alcoholic drink a day for women and two a day for men. Light drinking describes those who drink less than moderate drinkers but more than those who totally abstain from alcohol.
In a study that involved over 3000 adults over the age of 75, light to moderate drinking was associated with a 42% lower risk of Alzheimer's disease and a 29% lower risk of all types of dementia.
One study found that among women who were over the age of 90, a decrease in alcohol consumption was associated with an increase in the development of mild cognitive impairment and dementia.
Another study considered how alcohol consumption affected people with a diagnosis of mild cognitive impairment (MCI). (MCI sometimes, but not always, progresses to dementia.
) This study demonstrated that light to moderate alcohol consumption was associated with a decreased chance of mild cognitive impairment progressing into full dementia.
Participants who never drank alcohol had a higher chance of developing dementia than those who were light to moderate drinkers, while heavy drinkers were the most ly to progress to dementia.
Of interest, researchers in one study identified the participants who were APOE-ε4 carriers and those who did not carry this gene. (APOE-ε4 is a gene that is associated with an increased risk of Alzheimer's disease.
) Study participants who were light to moderate alcohol drinkers and who carried the APOE-ε4 gene were at an increased risk of cognitive decline and memory loss, while light to moderate drinkers who did not carry the APOE-ε4 gene demonstrated improved learning ability and memory.
It depends on whom you ask. Research has come to different conclusions about this question. Multiple studies have cited wine as specifically having protective effects on people's memory and cognitive ability. Other studies, however, have concluded that wine, beer, and liquor all have similar effects on cognition.
There are some people that should not drink alcohol.
This group includes but is not limited to alcoholics, people with Wernicke-Korakoff syndrome, those taking certain medications that could negatively interact with alcohol, people with certain medical conditions such as liver disease and pancreatitis, those who are under the legal age to drink, women who are (or are attempting to become) pregnant and those who are operating a vehicle or performing other complex tasks.
Other studies have found that drinking alcohol has other health risks; thus, your decision to drink alcohol should be discussed with your doctor.
For many people, research suggests that light to moderate drinking of alcohol seems to have a protective benefit on dementia risk. However, it's important to remember that alcohol use can lead to dependence and abuse, so caution is warranted.
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- Dementia Collaborative Research Center. Your Brain Matters. Alcohol- Evidence.
- Downer B, Zanjani F, Fardo DW. The relationship between midlife and late life alcohol consumption, APOE e4 and the decline in learning and memory among older adults. Alcohol Alcohol. 2014;49(1):17-22. doi:10.1093/alcalc/agt144
- Hoang TD, Byers AL, Barnes DE, Yaffe K. Alcohol consumption patterns and cognitive impairment in older women. Am J Geriatr Psychiatry. 2014;22(12):1663-7.
- Michaël Schwarzinger, Bruce G Pollock, Omer S M Hasan, Carole Dufouil, Prof Jürgen Rehm, QalyDays Study Group.Contribution of alcohol use disorders to the burden of dementia in France 2008–13: a nationwide retrospective cohort study.The Lancet Public Health, 2018;3(3). doi:10.1016/S2468-2667(18)30022-7
- Nordström P, Nordström A, Eriksson M, Wahlund LO, Gustafson Y. Risk factors in late adolescence for young-onset dementia in men: a nationwide cohort study. JAMA Intern Med. 2013;173(17):1612-8.
- Weyerer S, Schäufele M, Wiese B, et al. Current alcohol consumption and its relationship to incident dementia: results from a 3-year follow-up study among primary care attenders aged 75 years and older. Age Ageing. 2011;40(4):456-63. doi:10.1093/ageing/afr007
- Xu G, Liu X, Yin Q, Zhu W, Zhang R, Fan X. Alcohol consumption and transition of mild cognitive impairment to dementia. Psychiatry Clin Neurosci. 2009;63(1):43-9.
expert reaction to study looking at alcohol and risk of dementia and cognitive decline
Research, published in JAMA Network Open, reports on a link between a moderate but non-zero consumption of alcohol and reduced risk of developing dementia.
Prof Tara Spires-Jones, UK Dementia Research Institute Programme Lead, and Deputy Director of the Centre for Discovery Brain Sciences, University of Edinburgh, said:
“Dr Jensen and colleagues from Harvard have looked at whether there is an association between alcohol consumption and risk of dementia or declining cognitive ability during ageing. Although this is a well conducted study, the data reported here do not prove that that drinking alcohol prevents dementia.
“This kind of observational study has several limitations. The participants were asked to report their alcohol consumption and may not have accurately remembered how much they drank per week. Further, small amounts of daily alcohol consumption may be linked to other behaviours that affect dementia risk such as being socially active.
“While this is a useful scientific study, we need more research into how alcohol affects the brain changes that cause dementia to fully understand the implications.”
Dr Sadie Boniface, Research Coordinator, Institute of Alcohol Studies, said:
“This is a well done study with a large number of participants. The researchers found drinking less often but more heavily, compared with more frequent lighter drinking, was associated with greater dementia risk and recommends doctors look to understand older patients’ drinking patterns.
“This study did not find any level of drinking cut dementia risk.
There was a lower estimate of dementia risk for some groups of moderate drinkers, but it’s really important to know that scientists use a margin for error around these types of statistics, and this study does not conclude drinking prevents dementia. In the authors’ own words: “our results did not show significant associations and clearly do not suffice to suggest a clinical benefit from even limited alcohol use.”
“The relationship between alcohol and dementia also has to be considered in the wider picture of older people’s drinking, including the increased risk of falls and complications around alcohol interacting with medicines.
“There are other studies finding moderate drinking is associated with lower risks of various chronic diseases (namely heart disease) compared to abstainers. But the evidence on this is complicated, with many people who abstain from alcohol doing so precisely because of poor health.”
Prof Clive Ballard, Professor of Age-Related Diseases, University of Exeter Medical School, said:
“We need to interpret these findings with caution. It’s a relatively small study, and it’s really difficult to compare a group of drinkers to those who are teetotal or drink very little, because it’s hard to control for a range of different cultural and health issues that may have an effect.
It’s interesting that seven to 14 drinks a week seems to be associated with a benefit in people with mild cognitive impairment, but we’d need larger-scale research to confirm this. From what we know, it seems unly that even small amounts of alcohol are beneficial.
We now need a thorough analysis to look at all research that focuses on the lower end of alcohol consumption, so we can really work out a threshold of where dementia risk starts.”
Dr James Pickett, Head of Research, Alzheimer’s Society said:
“The suggestion that moderate alcohol intake could decrease your risk of developing dementia must be taken with caution – for example, we don’t know if low alcohol consumption could actually be an effect of early dementia, rather than a cause.
“This study reflects similar previous studies – when it comes to excessive alcohol consumption, there are health risks. Particularly in older adults and those already living with cognitive impairments.
“With one person being diagnosed every three minutes – prevention is key. Through our PREVENT programme Alzheimer’s Society is following 700 people long term to understand their lifestyles in midlife and the influence this has on brain health.
Our aim is to have a better understanding of risk factors for developing dementia, and help people make lifestyle changes, such as opting for a non-alcoholic cocktail, and getting regular exercise, a walk with friends or an exercise class.
Dr Dorina Cadar, Senior Research Fellow, UCL Behavioural Science and Health, UCL, said:
“The study by Koch and colleagues published today in JAMA Network Open shows a differential effect of alcohol consumption on dementia risk among participants with and without mild cognitive impairment at baseline, from the Ginko Evaluation of Memory Study. Among those who were cognitively fit at the beginning of the study, daily but low quantity alcohol consumption was associated with a reduced dementia risk compared to infrequent hazardous drinking.
“These findings support previous evidence found in the UK and elsewhere, suggesting that low to moderate alcohol consumption could be protective for cardiovascular and brain health.
Moderate alcohol exposure could trigger anti-inflammatory mechanisms in the brain that tend to promote cellular survival pathways, which could protect against ischemia, endotoxin, and beta-amyloid formation.
In addition to the antioxidant properties of alcohol itself, the antioxidant effect of polyphenols (such as resveratrol), which are abundant in red wine, has been proposed to be neuroprotective.
The association may also operate through embolism or decreased cerebral perfusion supporting the popular saying “what’s good for the heart is also good for the brain”. However, this study is observational, and we cannot infer causality; therefore we cannot say whether it is the alcohol or something else that is responsible for the lower, and higher dementia and cognitive impairment risks.
“Not surprising, the protective association of alcohol consumption was no longer significant in participants entering this study with some form of cognitive impairment.
This indicates that participants experienced certain molecular modifications that are part of a long sequence cascade of neuropathological changes happening in the brain, years before the first signs of cognitive deterioration occurred.
Whether individuals without cognitive impairment before death can harbour severe Alzheimer-type pathology is not exactly clear, but many studies confirm mixed cerebrovascular pathologies and neuropathological findings, and there is also evidence suggesting that 10-20% of those diagnosed with mild cognitive impairment tend to progress to a form of dementia within 5 to 10 years.
“Primary prevention, including healthy lifestyle behaviours such as moderate alcohol consumption, healthy dietary patterns increased level of exercise and non-smoking should happen earlier in life. Dementia prevention, in particular, depends on the initiation and maintenance of behavioural changes to delay cognitive impairment; but more research is essential to clarify its validity.”
Prof Lawrence Rajendran, Van Geest Professor of Dementia Research and Deputy Director of the Dementia Research Institute, King’s College London, said:
“In the world where we care a lot about extending not just lifespan but also healthspan in the name of longevity and advancing healthcare in the name of medicine – this study sheds light on an important yet, often forgotten other ingredient of life: Happiness.
This study, largely centred on older adults around 80 years old – thus not generalising for the entire demographics (kids, this is not for you!) – suggests that light to moderate drinking is actually associated with a reduction in risk of developing dementia.
This study, now conducted with 3021 subjects, replicates an earlier study conducted with 176 subjects (Xu et al, https://doi.org/10.1111/j.1440-1819.2008.01904.x) confirming that light to moderate alcohol consumption is associated with a reduced risk for transitioning from mild cognitive impairment to Alzheimer’s disease.
While the biological basis for this effect is still unknown and needs to be investigated, and this is only observational data so cannot prove cause and effect, it does underlie the roles of depression and anxiety in worsening cognitive dysfunction.
I recently told my 76 year old mother, who has lived an amazing and purposeful life so far, to indulge in a bit of light alcohol drinking and not cut calories in the name of: Live a little, more.”
Dr Graham Wheeler, Senior Statistician, UCL, said:
“The results of this study do not conclusively show that drinking alcohol reduces the risk of developing dementia.
“Whilst the study estimated an average reduction in risk of developing dementia of 37% when comparing those drinking 7-14 drinks to those drinking up to 1 drink a week, this could reasonably be anywhere between a 62% reduction and a 6% increase. For participants with MCI, there is little evidence to suggest that the 7% average reduction is genuinely due to increased alcohol consumption; it is ly due to chance.
“Alcohol consumption is self-reported, so may not be a reliable record of what participants consumed. Also, alcohol consumption was measured by considering the intake of beer, wine and hard liquor, but no accounting for differing alcohol content between different types of drink was made.”
Dr Sara Imarisio, Head of Research at Alzheimer’s Research UK, said:
“There’s a well-established link between heavy drinking and the risk of dementia, but it is difficult to say whether moderate alcohol intake has any impact on brain health when compared to not drinking at all.
“Some non-drinkers may have a history of heavy alcohol use, and this makes it difficult to untangle links between drinking habits and health.
“This study only looked at people’s drinking in later life, and we don’t know about their drinking habits in their earlier years. Research suggests that our lifestyle in middle age may have the greatest impact on our future risk of dementia.
“There are many good health reasons to keep an eye on how much alcohol you’re drinking. Current alcohol guidelines recommend not regularly drinking more than 14 units a week for both men and women.
“Dementia is caused by physical diseases of the brain, but there are things we can do to reduce the risk of developing dementia.
The best current evidence indicates that as well as only drinking within the recommended guidelines, staying physically and mentally active, eating a healthy balanced diet, not smoking, and keeping weight, cholesterol and blood pressure in check are all good ways to keep the brain healthy as we age.”
‘Alcohol Consumption and Risk of Dementia and Cognitive Decline Among Older Adults With or Without Mild Cognitive Impairment’ by Manja Koch et al. was published in JAMA Network Open at 16:00 BST on Friday 27 September 2019.
Prof Tara Spires-Jones: “I have no conflicts with this paper.”
Dr Sadie Boniface: “I work at the Institute of Alcohol Studies which is funded by the Alliance House Foundation. I am also a visiting researcher at the Addictions Department at the Institute of Psychiatry, Psychology & Neuroscience at King’s College London.
The Institute of Alcohol Studies is a small charity based in Westminster and we do research as well as policy work. Our role is to advance the use of the best available evidence in public policy decisions on alcohol. More details and info on how we are funded here: http://www.ias.org.
Dr Dorina Cadar: “No competing interests.”
Prof Lawrence Rajendran: “I declare no competing or conflicts of interests for my statement.”
Dr Graham Wheeler: “I am employed by UCL, am a Fellow, Chartered Statistician and Statistical Ambassador of the Royal Statistical Society, and a voluntary research committee member for Chiltern Music Therapy, a not-for-profit organisation providing music therapy services. I have previously received honoraria from Novametrics Consulting Ltd.”
None others received.