Critique 100: The effects of moderate drinking on cognitive function and dementia: An update — 15 January 2013
Panza F, Frisardi V, Seripa D, Logroscino G, Santamato A, Imbimbo BP, Scafato E, Pilotto A, Solfrizzi V. Alcohol consumption in mild cognitive impairment and dementia: harmful or neuroprotective? Int J Geriatr Psychiatry 2012;27:1218-1238.
Objective: In several longitudinal studies, light-to-moderate drinking of alcoholic beverages has been proposed as being protective against the development of age-related changes in cognitive function, predementia syndromes, and cognitive decline of degenerative (Alzheimer’s disease, AD) or vascular origin (vascular dementia). However, contrasting findings also exist.
Method: The English literature published in this area before September 2011 was evaluated, and information relating to the various factors that may impact upon the relationship between alcohol consumption and dementia or predementia syndromes is presented in the succeeding texts.
Results: Light-to-moderate alcohol consumption may be associated with a reduced risk of incident overall dementia and AD; however, protective benefits afforded to vascular dementia, cognitive decline, and predementia syndromes are less clear. The equivocal findings may relate to many of the studies being limited to cross-sectional designs, restrictions by age or gender, or incomplete ascertainment. Different outcomes, beverages, drinking patterns, and study follow-up periods or possible interactions with other lifestyle-related (e.g., smoking) or genetic factors (e.g., apolipoprotein E gene variation) may all contribute to the variability of findings.
Conclusion: Protective effects of moderate alcohol consumption against cognitive decline are suggested to be more likely in the absence of the AD-associated apolipoprotein E e4 allele and where wine is the beverage. At present, there is no indication that light-to-moderate alcohol drinking would be harmful to cognition and dementia, and attempts to define what might be deemed beneficial levels of alcohol intake in terms of cognitive performance would be highly problematic and contentious.
Background: There has been considerable discussion in recent years on the association between the consumption of wine and other types of alcohol and cognitive function. The majority of well-done prospective studies have shown that moderate drinking, especially of wine, is associated either with no significant effect or, more commonly, with a significant and rather large decrease in the risk of the cognitive impairment associated with ageing. Further, most studies suggest that moderate drinking is associated with a reduction in the risk of Alzheimer’s disease and other types of dementia.
Specific comments on the paper: Forum reviewer Ellison stated that this paper provides a good update on this topic. “It is very inclusive and presents a balanced discussion of the difficulties encountered when having to use observational data (as from non-interventional epidemiologic studies) as a basis for making recommendations to the public regarding alcohol use.” He continued: “The paper presents brief summaries of results from most key epidemiologic studies dealing with this topic between 1987 and 2011. It describes the results of recent reviews and meta-analyses (by Peters et al, 2008; Antsley et al, 2009; Lee et al, 2010; Neafsey & Collins, 2011), all of which concluded that moderate drinking is associated with lower risk of cognitive decline and dementia (usually a 20-35% lower risk for moderate drinkers in comparison with non-drinkers). The paper points out difficulties caused by studies that often lack data on beverage type, and especially by studies without any information on the pattern of drinking. It gives a brief discussion of potential mechanisms for such an effect.”
On the other hand, some Forum members considered this paper to provide little new insight into the relation of alcohol consumption to cognitive function. Stated reviewer Finkel, “This is certainly a well-done, useful work to be taken seriously. It, however, does not really add anything new. The epidemiologically based notion that moderate drinking reduces the risks of dementia has appeared in respectable scientific publications for more than two decades, and has been noted in folk wisdom and by sages of various persuasions since biblical times. I am unmoved by the authors’ biochemical speculations, for they add no new data. We are all hoping for studies that directly address confounding factors and biological mechanisms.”
Stated Forum reviewer Skovenborg, “The subject of cognitive decline, predementia and the various types of dementia is a notoriously difficult subject to study and some heterogeneity, bias and confounding is to be expected. Nonetheless several recent meta-analyses indicate that light to moderate alcohol consumption is associated with a significantly reduced (25-32%) risk of dementia. The evidence is best for older people with recently updated information on alcohol use. With that in mind the conclusion of the authors that ‘there is at present no indication that light-to-moderate alcohol drinking would be harmful to cognition and dementia’ is at best self-evident and at worst reflects only ‘political correctness.’ The authors do not present data to substantiate their claim that attempts to define what might be beneficial effects of alcohol on cognition would be ‘highly problematic and contentious.’”
Forum member Ursini stated: “I agree with the comments of previous reviewers and I would like to stress that it’s time now to dedicate more efforts (and money) to get some light on basic mechanisms. Such a relevant issue in human health cannot be restricted to observational studies. Another comment is about the title: saying ‘harmful or neuroprotective’ gives the impression of a still open issue on which there is debate, while data only describe a neuroprotective effect. The title seems biased by a kind of prejudice of the authors that are not fully convinced also about their own results.”
Forum reviewer Goldfinger was impressed with the paper: “This was an ambitious project that reviews relevant data pertaining to alcohol and dementia. I concur that there remains some ambiguity and overlap among dementia syndromes; however, as defined, Alzheimer’s Dementia accounts for the bulk of patients suffering from dementia, and here moderate alcohol has a consistent beneficial effect. Whereas this review was not intended to add new light to the subject, it is well done, and provides insight by nature of its extensive content. The authors were objective and unbiased.”
References from Forum review
Anstey KJ, Mack HA, Cherbuin N. Alcohol consumption as a risk factor for dementia and cognitive decline: meta-analysis of prospective studies. Am J Geriatr Psychiatry 2009;17:542–555.
Lee Y, Back JH, Kim J, et al. Systematic review of health behavioral risks and cognitive health in older adults. Int Psychogeriatr 2010;l22: 174–187.
Neafsey EJ, Collins MA. Moderate alcohol consumption and cognitive risk. Neuropsychiatr Dis Treat 2011;7:465–484.
Peters R, Peters J, Warner J, Beckett N, Bulpitt C. Alcohol, dementia and cognitive decline in the elderly: a systematic review. Age Ageing 2008;37:505–512.
A paper from a group of Italian scientists provides an extensive review of the available research relating alcohol consumption to cognitive function. It presents brief summaries of results from most key epidemiologic studies dealing with this topic between 1987 and 2011. The large majority of these studies, and recent meta-analyses, support a finding of a lower risk of cognitive impairment from ageing and of dementia to be associated with moderate drinking.
Reviewers praised the authors for pointing out difficulties caused by having to develop guidelines for alcohol consumption based only on observational data, and not having large clinical trials for judging effect. A further problem faced in judging the numerous studies on this topic is that many lack data on beverage type and most lack detailed information on the pattern of drinking, which may be especially important in judging the effects of drinking.
Some reviewers stated that the paper does not present anything new, as previous meta-analyses have clearly shown a potentially protective effect of moderate alcohol consumption on the risk of cognitive decline and dementia. Given that recent large meta-analyses have shown that moderate drinking, in comparison with abstention, is usually associated with 20-35% lower risk of cognitive decline and dementia, Forum reviewers thought that the conclusions of the authors of this review paper were unnecessarily cautious. Overall, current scientific data support a conclusion that moderate consumption of alcoholic beverages, especially of wine, is neuroprotective.
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Comments on this review were provided by the following members of the International Scientific Forum on Alcohol Research:
Harvey Finkel, MD, Hematology/Oncology, Boston University Medical Center, Boston, MA, USA
Erik Skovenborg, MD, Scandinavian Medical Alcohol Board, Practitioner, Aarhus, Denmark
Arne Svilaas, MD, PhD, general practice and lipidology, Oslo University Hospital, Oslo, Norway
David Vauzour, PhD, Senior Research Associate, Department of Nutrition, Norwich Medical School, University of East Anglia, Norwich, UK
Fulvio Ursini, MD, Dept. of Biological Chemistry, University of Padova, Padova, Italy;
Tedd Goldfinger, DO, FACC, Desert Cardiology of Tucson Heart Center, Dept. of Cardiology, University of Arizona School of Medicine, Tucson, Arizona, USA
Ulrich Keil, MD, PhD, Institute of Epidemiology and Social Medicine, University of Münster, Münster, Germany
Dominique Lanzmann-Petithory,MD, PhD, Nutrition/Cardiology, Praticien Hospitalier Hôpital Emile Roux, Paris, France
David Van Velden, MD, Dept. of Pathology, Stellenbosch University, Stellenbosch, South Africa
Pierre-Louis Teissedre, PhD, Faculty of Oenology – ISVV, University Victor Segalen Bordeaux 2, Bordeaux, France
Giovanni de Gaetano, MD, PhD, Research Laboratories, Catholic University, Campobasso, Italy
R. Curtis Ellison, MD, Section of Preventive Medicine & Epidemiology, Boston University School of Medicine, Boston, MA, USA