Weyerer S, Schäufele M, Wiese B, Maier W, Tebarth F, van den Bussche H, Pentzek M, Bickel H, Luppa M, Riedel-Heller SG, . 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 Jul;40(4):456-63. PubMed.
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East London Foundation Trust
The German study on people 75 years and older by Weyerer and colleagues is another attempt to understand the relationship between alcohol and incident dementia. The study differs from previous studies due to the older age group of the sample population.
This is a three-year follow-up study of over 3,000 participants, looking at the relationship between their current alcohol consumption and DSM-IV dementia. No participants were considered to have a dementing illness by their general practitioner at the start of the study. There could have been a potential sampling bias as a large group of people were considered ineligible for various factors, for example, “having irregular patients” or “inability to give consent.” They could potentially have higher chances of having alcohol problems and/or cognitive impairments. Thereby, a healthier sample could have entered the study.
According to the researchers, 217 (6.8 percent) of the 3,202 subjects were diagnosed with dementia during the three-year period. Of these, 111 (3.5 percent) were diagnosed with Alzheimer’s disease. This is quite large, but the advanced age group of this population makes it understandable. They reported that alcohol consumption was significantly associated with lower incidence of overall dementia and Alzheimer’s disease. With regard to quantity of alcohol use and reduced incidence of dementia, they found that those reporting consumption of 20-29 grams of alcohol per day were the only group to have a statistically significant association. They did not report any variation in the effect of different types of alcohol on dementia. The findings are roughly consistent with existing literature, which supports the benefits of mild to moderate drinking over abstinence or heavy drinking in younger age groups. Interestingly, they did not find any association with ApoE4 allele status.
They also reported that alcohol consumption was significantly associated with male gender, younger age, higher levels of education, not living alone, and not being depressed. The study has almost twice the number of female participants than males, and this difference is not addressed while taking into account factors such as depression in this sample. Also, the paper fails to inform us about the treatment and outcomes of the depressed subgroups (as pseudodepression is a well-known reversible cause for cognitive decline, and there is a relationship between alcohol intake and mood problems).
Overall, this is a useful study that again seems to show the J-shaped relationship of long-term alcohol use and cognitive outcomes. The relationship between drinking alcohol and cognitive outcomes is quite complex. Often, it is hard to take into account the duration and chronicity of drinking (something missing in this paper), the effect of dementia on the drinking itself (dementing people can show reduction of drinking), and other lifestyle factors. Older people who are cognitively intact and remain active may have better social lives and access to alcohol. In conclusion, this is an interesting paper, and especially so as it targets a much older population than previously studied. It seems to confirm the finding of previous research in this field but has similar methodological problems that are associated with such studies.
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