Does Alcohol Consumption Affect the Risk of Dementia from Alzheimer’s Disease?

For today’s post, we’ll be examining a relatively brief study published earlier in 2011 regarding alcohol consumption and its effects on incident and Alzheimer’s dementia.  Compared to other studies I’ve reviewed in the past, this one is much shorter, but the results of which are still interesting.

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Studies have shown that long term alcohol consumption can have many negative health effects, including increased incidence of dementia, decreased memory function, and other various neurodegenerative diseases.  Out of all cases of dementia, 10% of them are related to alcohol consumption.  However, some studies have shown that light to moderate alcohol consumption has the opposite effect, in that it decreases the risk for dementia, Alzheimer’s dementia, and cognitive decline, but not vascular dementia.  Research is ongoing in regards to why light to moderate alcohol consumption may have protective effects against these neurodegenerative diseases, but current thought is that it may increase the serum concentrations of high-density lipoproteins; lower cholesterol; positively benefit platelet function, blood clotting and fibrinolysis; and improve insulin sensitivity.

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Also unclear is whether or not specific types of alcohol share the same protective effects, or if one type is more beneficial (or detrimental) than another.  In one of the first posts I ever wrote on this blog, I reviewed an article looking at alcohol consumption and how different types of alcohol affected cognitive abilities (you may read the article by clicking here).  After controlling for socioeconomic factors, that study found conflicting results in that some types of alcohol were beneficial for different cognitive functions (wine and sometimes spirits), while others were detrimental for different cognitive functions (beer).  Studies to date have shown conflicting results of this type of research, thereby requiring more work to be done on the subject.

The current study was focused in Germany, where no information regarding the relationship between alcohol consumption and dementia is available.  Also, the study looked at adults older than age 75, which up until this point, had been the oldest individuals studied for this type of research.

Methods

All of the individuals chosen for the study were residents of cities with populations between 300,000 and 1.8 million.   138 General Practitioners offices participated in the study, which selected participants based on the following criteria: 1) participants were 75 years old or older; 2) participants had at least one general practitioner visit within the last year; and 3) the participant did not have dementia at the time of selection.

At the baseline assessment, 3,327 participants were interviewed.  Follow-up interviews were conducted 1.5 and 3 years after the baseline appointment.  For those participants who died in the interim, necessary information for the study was collected from family members of the deceased.  Out of the 3,327 participants, 84.8% were interviewed 1.5 years later (2,820 participants), and 73.9% were interviewed 3 years later (2,460 participants). 

To determine alcohol use, self-reported surveys were used.  Participants were asked questions including how often they drank, in addition to how much they drank, and what type of alcohol did they drink.  Participants were also asked if they were smokers, in case that had any confounding effects on the results of the study.  Mental and physical health was assessed by giving participants a diagnostic assessment of dementia, a mild cognitive impairment test, a test for depression, and also the daily activities performed.  DNA analysis was also performed.

Results

  • ¬† ¬† ¬† The total number of participants at the baseline that did not have dementia (and thus considered for further study) was 3,202, with alcohol information available for 3,180 of them.
  • ¬† ¬† ¬† 50% of participants did not drink alcohol.¬† 24.8% consumed less than one drink per day.¬† 12.8% consumed 1-2 drinks per day.¬† 12.4% consumed 2 or more drinks per day.¬† 25 participants consumed a harmful amount of alcohol per day (>6 drinks).¬† One man reported he consumed >12 drinks per day, and one woman reported she consumed >8 drinks per day.
  • ¬† ¬† ¬† Out of those participants that drank alcohol, 48.6% consumed wine only, 29% consumed beer only, and 22.4% consumed a variety of wine, beer, and spirits.
  • ¬† ¬† ¬† There was no association between alcohol consumption and functional impairment, somatic co-morbidity, smoking, mild cognitive impairment status, or apoE4 status.
  • ¬† ¬† ¬† Within the 3 year follow-up after baseline, there were 217 cases of dementia reported (6.8%), and 111 cases of Alzheimer‚Äôs dementia reported (3.5%). ¬†Other forms of dementia were excluded from analysis, since the frequency in the group of participants was too low for statistical analysis.
  • ¬† ¬† ¬†¬†Alcohol consumption was significantly associated with a lower incidence of overall dementia and Alzheimer‚Äôs dementia.
  • ¬† ¬† ¬† In regards to the amount of alcohol consumed, those consuming between 2 and 3 drinks per day showed negative effects on mental status than those consuming light to moderate amounts.
  • ¬† ¬† ¬† In regards to the type of alcohol consumed, those drinking mixed alcoholic beverages showed negative effects on mental status than those consuming wine alone or beer alone.

What does this all mean?

Even though the results of this study were relatively short, there is much speculation regarding the results shown.  The overall finding of this study was that light to moderate alcohol consumption was associated with relatively good physical and mental health.  It was also found that alcohol consumption was significantly associated with factors that happen to be protective against the symptoms of dementia, including a better education, not living alone, and the absence of depression.  However, even after controlling for these and other social and economic factors, the risk of incident dementia was still lower among those consuming light to moderate amounts of alcohol.

These results prove to be consistent with other studies findings that incident dementia is decreased when light to moderate amounts of alcohol are consumed.  These results have been shown for adults up to age 75, and now with this study, it is shown that the results hold for those aged 75 or older.  The Cardiovascular Health Study, which showed results very similar to these, found that when compared with non drinkers, the adjusted odds for dementia among those with weekly alcohol consumption of less than one drink was 0.65; the odds 1-6 drinks was 0.46; the odds for 7-13 drinks was 0.69; and the odds for 14+ drinks was 1.22.

In regards to the type of alcohol consumed, it appeared from this study that wine alone or beer alone both acted to lower the risk of dementia in participants, however, for those drinking a mixed variety of alcoholic beverages, the risk was higher.  This is in line with several studies that found that the three beverage types (wine, beer, and spirits) did not differ in regards to their relationships with dementia.  However, these results conflict with the results of other studies, such as studies in Göteborg, New York, Copenhagen, Canada, and France, in that these studies found that only wine consumption was associated with a decreased risk of dementia.  The conflicting results indicate that even more research needs to be done, and more factors need to be accounted for in order to see true relationships.

The authors of this study point out possible pitfalls of the study methods, which may or may not have contributed to the results shown.¬† First, since only about 50% of the selected participants agree to be in the study, there may have been some selection bias occurring.¬† Second, the study excluded those potential participants in nursing homes, and also those that did not regularly visit a general practitioner.¬† Third, alcohol consumption was self-reported, and even though this type of survey is an acceptable method, participants may not have been completely truthful in reporting their own alcohol intake, as a result of the amount of alcohol that is socially acceptable to consume, and potential embarrassment for indicating any amounts higher.¬† Finally, ‚Äúformer drinkers‚ÄĚ were included in the same category as ‚Äúnever drinkers‚ÄĚ, which may have altered the data somehow.¬† It is also possible that those that drink alcohol light to moderately have a healthier lifestyle in general than those who consume heavy amounts of alcohol, which could also lead to decreased risk of dementia.

Though this study does not seem to clear up the controversy in regards to type of alcohol consumption and effects on dementia and Alzheimer’s risks, it does show that for German adults aged 75 and older, light to moderate alcohol consumption is inversely related to incident dementia and incident Alzheimer’s dementia.  More work certainly needs to be done in order to tease out whether or not different types of alcohol have different effects on dementia, however, one thing is clear in that in every study done to date, light to moderate wine consumption has almost always been beneficial and always shows a decreased risk of dementia.

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I’d love to hear what you all think! Please feel free to comment below, and share with your friends/colleagues!

Source: doi: 10.1093/ageing/afr007

I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!