September 27, 2019

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 unlikely 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, like 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 likely 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.

DOI: 10.1001/jamanetworkopen.2019.10319

Declared interests

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.uk/Who-we-are.aspx”

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.