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Moderate drinking linked to reduced risk of death in early stage Alzheimer’s disease
Death rates lower among those totting up 2-3 daily units than among drinkers of more or fewer
Drinking 2 to 3 units of alcohol every day is linked to a reduced risk of death among people with early stage Alzheimer’s disease, finds research published in the online journal BMJ Open.
Moderate drinking has been associated with a lower risk of developing and dying from heart disease and stroke. But alcohol is known to damage brain cells, and given that dementia is a neurodegenerative disorder, drinking might be harmful in those with the condition.
The researchers therefore wanted to find out if the same potentially positive association between alcohol and a reduced risk of cardiovascular death could be applied to 321 people with early stage Alzheimer’s disease, defined as a score of 20 or less on the Mini Mental State Exam (MMSE).
The research team analysed data originally collected on 330 people with early stage dementia or Alzheimer’s disease and their primary carers from across Denmark as part of the Danish Alzheimer’s Intervention Study (DAISY).
DAISY set out to assess the impact of a 12 month programme of psychosocial counselling and support, and tracked progress for three years afterwards, accumulating a considerable amount of data.
This included information on how much alcohol people with early stage dementia or Alzheimer’s drank every day. Around one in 10 (8%) drank no alcohol and at the other end of the scale, around one in 20 (4%) drank more than 3 units daily.
Most of the sample (71%) drank 1 or fewer units a day; 17% drank 2-3 units.
During the monitoring period, 53 (16.5%) of those with mild Alzheimer’s disease died. Consumption of 2-3 units of alcohol every day was associated with a 77% lowered risk of death compared with a tally of 1 or fewer daily units.
There was no significant difference in death rates among those drinking no alcohol or more than 3 units every day compared with those drinking 1 or fewer daily units.
These results held true after taking account of influential factors: gender, age, other underlying conditions, whether the individual lived alone or with their primary carer, educational attainment, smoking, quality of life, and MMSE result.
The researchers say there could be several explanations for the findings, including that people who drink moderately have a richer social network, which has been linked to improved quality, and possibly length, of life.
Another explanation may lie in the fact that the seemingly protective effect of alcohol may have been caused by reverse causality, whereby those drinking very little alcohol were in the terminal phase of their life, which would have artificially inflated the positive association.
In a bid to correct for this, the researchers re-analysed the data, omitting the first year of monitoring. But this made no difference to the findings.
“The results of our study point towards a potential, positive association of moderate alcohol consumption on mortality in patients with Alzheimer’s disease. However, we cannot solely, on the basis of this study, either encourage or advise against moderate alcohol consumption in [these] patients,” they caution.
They suggest that further research looking at the impact of alcohol on cognitive decline and disease progression in patients with mild Alzheimer’s disease would be particularly informative.
Notes for editors:
Research: Alcohol consumption and mortality in patients with mild Alzheimer’s disease: a prospective cohort study doi 10.1136/bmjopen-2015-007851
Journal: BMJ Open
Expert Reaction
These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.
Dr Christina Perry is a researcher in the Behavioural Neuroscience division at the Florey Institute of Neuroscience and Mental Health
The basic finding of this paper is that in people with Alzheimer’s disease, those that drank a moderate amount (here 2-3 standard drinks, but note that these standard drinks are larger than Australian standard drinks), were less likely to die within a 3 year follow-up period than those that did not drink, drank a low amount, or drank more than 3 standard drinks per day. Generally, drinking is actively discouraged in Alzheimer’s sufferer, despite the fact that there is no pathological relationship between these Alzheimer’s and alcohol-related dementia. Here, we see that moderate alcohol consumption may actually have some benefits. Importantly, though, the study does not deal at all with the effect of alcohol on the development or progression of the disease itself. Also, it is not clear from this study whether the reduced rate of mortality is something that is specific to those suffering from Alzheimer’s, or just a more general health benefit (which has been shown before).
For me, there are a couple of striking problems with the study, which are openly acknowledged by the authors. The first is that the group sizes are vastly unequal, and some of the groups are much too small to be able to make any confident conclusions about applicability in the broader population. The second is that drinking is only measured at a single time point, and therefore is very much influenced by current circumstance. For example: people might have been drinking less because they were quite sick – and this of course would influence mortality rate. It’s an interesting initial finding, especially given that it contradicts conventional wisdom that people with Alzheimer’s should not drink, and it has the potential for implications, particularly for those in a caregiving role. However, in my view, further investigation is necessary before it has any real impact.
Professor Henry Brodaty is Co-Director of the Centre for Healthy Brain Ageing (CHeBA) at UNSW
This interesting study that states that moderate alcohol intake is protective against mortality in people with Alzheimer's or mixed dementia seems counter-intuitive. A Danish unit of alcohol is 12 g/15 mL of pure alcohol (a UK unit of alcohol is 10 mL of pure alcohol; this would be equivalent to 3 to 4.5 standard drinks in Australia). This was a post hoc analysis meaning it had not been planned. It only asked about current alcohol intake so that people who were sicker may have already cut down. Not all potential factors which may have explained these results, called confounders, were measured. So we should be cautious about accepting the implication that we should drink 2-3 units/ day of alcohol to reduce mortality.
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