Alcohol and Cognitive Function/Dementia

Critique 233:  The relation of alcohol consumption to the development of dementia, with very extensive evaluations of the latter – 7 November 2019

This study was designed to assess the association between alcohol consumption and dementia and the roles of mild cognitive impairment (MCI) and apolipoproteinEε4 (APOEE4) genotype in modifying this association.  It was based on data from the Ginkgo Evaluation of Memory Study, conducted from 2000 to 2008 among US community-dwelling participants (which did not demonstrate beneficial effects of ginkgo). The study analyzed 3,021 participants aged 72 years and older who were free of dementia at baseline.

The assessment of alcohol consumption included both the amount and frequency of intake, and the authors had a very broad assessment of potential confounders, including cardiovascular and other diseases, depression, race, ethnicity, educational level, social activity, medication use, and genotype for APOE-E4.  There was a very complete and careful attention to the assessment of cognitive function, as subjects underwent numerous and repeated cognitive assessments.  For example, if there was any suggestion of cognitive impairment, cerebral magnetic resonance imaging and referral to an expert panel of clinicians, who reviewed and validated presence of dementia, was carried out.  No previous studies have had such an extensive assessment of cognition.

The main results include a finding that for the large majority of participants (the 2,548 without mild cognitive impairment at baseline), complete abstention from alcohol was associated with a slightly higher risk of dementia than seen in any of the groups consuming alcohol.  For 473 subjects with MCI at baseline, there was no effect on risk of dementia for up to about 10 drinks/week, then a slight but insignificant increase in risk with greater intake.  Daily low-quantity drinking was associated with more than 50% lower dementia risk than infrequent higher alcohol consumption.  Many of the associations shown had a consistent pattern (a decrease in risk with light drinking) but did not reach statistical significance.  The association was similar for all sub-groups, and was not modified by APOEE4 genotype.

The analyses seem well done, and Forum members agreed that, while some of the associations did not reach statistical significance, the data support most previous studies that show a J-shaped or U-shaped association for the relation of alcohol consumption to the risk of dementia.  As has been shown in most previous studies, regular (even daily) light drinking was found to be preferable to infrequent higher levels of alcohol consumption in terms of the effect on the risk of dementia.

Reference:  Koch M, Fitzpatrick AL, Rapp SR, Nahin RL, Williamson JD, Lopez OL, et al.  Alcohol Consumption and Risk of Dementia and Cognitive Decline Among Older Adults With or Without Mild Cognitive Impairment.   JAMA Network Open 2019:2(9):e1910319.                                                                                       doi: 10.1001/jamanetworkopen.2019.10319

For the full critique of this paper by the International Scientific Forum on Alcohol Research, please click here.

Critique 223:  A new major review of the relation of alcohol consumption to the risk of dementia.    17 January 2019

While many studies have shown that excessive alcohol intake is associated with cognitive impairment and increased risk of dementia, most cohort studies have shown that the risks of these outcomes are lower among light-to-moderate drinkers than among abstainers.  The authors of this paper conducted a scoping review on this topic, based on a systematic search of systematic reviews published from January 2000 to October 2017.  A total of 28 systematic reviews were identified relating alcohol intake at various time periods to incidence of cognitive impairment/dementia, specific brain functions, or induced dementias.  The authors report that light to moderate alcohol use in middle to late adulthood was associated with a decreased risk of cognitive impairment and dementia, but heavy alcohol use was associated with changes in brain structures, cognitive impairments, and an increased risk of all types of dementia.

Forum members considered this to be a well-done analysis, but were concerned that the focus was only on the potentially adverse effects of heavy drinking, with little regard or discussion of the findings of protection against such cognitive outcomes among light or moderate drinkers.  Forum members point out that there are very many adverse health effects, both for the drinker and for society, resulting from heavy drinking.  To them, the most interesting and provocative aspect of this paper was the conclusion of a protective effect against cognitive decline and dementia associated with light-to-moderate alcohol consumption.

Scientific data, including the results of the present systematic analysis, are very consistent in showing that cognitive decline, associated impairments in the functions of daily living, incident dementia, and survival are all associated favorably with light-to-moderate consumption of alcohol in middle age.  The reasons and mechanisms that lead to these associations deserve further evaluation.  With the increasing ageing of populations throughout the world, cognitive decline and dementia are expected to increase and create serious challenges for health care providers.  Insight into ways of preventing or delaying the onset of such cognitive decline (in addition to decreasing the prevalence of heavy alcohol intake, the focus of this paper) could be extremely important in planning for the future.

Reference: Rehm J, Hasan OSM, Black SE, Shield KD, Schwarzinger M.  Alcohol use and dementia: a systematic scoping review.  Alzheimer’s Research & Therapy 2019; 11: pre-publication.  https://doi.org/10.1186/s13195-018-0453-0

For the full critique of this paper by the International Scientific Forum on Alcohol Research, please click here.

Critique 218: Long-term study of alcohol intake and the risk of Alzheimer Disease or other types of dementia – 21 August 2018

Reference: Sabia S, Fayosse A, Dumurgier J, Dugravot A, Akbaraly T, Britton A, Kivimäki M, Singh-Manoux A. Alcohol consumption and risk of dementia: 23 year follow-up of Whitehall II cohort study. BMJ 2018;362:k2927. http://dx.doi.org/10.1136/bmj.k2927

While there is general agreement that the moderate intake of alcohol is associated with a significantly lower risk of cardiovascular disease, there are less data on the relation of moderate alcohol consumption to dementia. However, the vast majority of well-done prospective studies indicate that, in comparison with non-drinkers, moderate, non-binge-drinking older adults have lower risk of Alzheimer Disease and other types of dementia. The present study provides important information on this association by monitoring for the development of dementia among subjects in a large cohort of British civil servants (the Whitehall Study) over more than two decades; there were repeated assessments of alcohol consumption.

The main results indicate that abstinence in middle life is associated with a significantly higher risk of dementia than the risk among moderate drinkers, while subjects reporting the intake of larger amounts of alcohol or evidence of an alcohol use disorder are at increased risk of dementia. Specifically, the study shows that among the 397 cases of dementia that were recorded over a mean follow up of 23 years, abstinence in midlife was associated with a 47% higher risk of dementia compared with consumption of 1-14 units/week (a British unit is the equivalent of 8 grams of alcohol). There was a 17% increase in risk of dementia for those reporting more than 14 units/week. With repeated assessments of alcohol the authors also calculated trajectories of alcohol consumption from midlife to early old age, with continued abstinence being associated with an increase in dementia of 74% and a decrease in consumption with an increase of 55% in comparison with subjects reporting continued moderate consumption. In several analyses, wine consumption was associated with more favorable effects than those of other beverages.

Forum members thought that this was a well-done analysis, but considered that the data presented do not allow for a firm determination of a cut-point for increased risk of dementia from alcohol intake. While the authors provide estimates of a linear increase in dementia risk for subjects reporting more than 14 units/week or reporting evidence of alcohol abuse, they do not give data that permits an estimate of the level of intake where the risk of dementia exceeds that of non-drinkers.

Overall, the results showing a decreased risk of dementia for moderate drinkers support the findings from most well-done prospective cohort studies. As for implications for policy, the study further shows that, in terms of the risk of dementia as well as cardiovascular disease, middle-aged and older individuals who are consuming alcohol moderately and without binge drinking should not be advised to stop drinking.

For the full critique of this paper by members of the International Scientific Forum on Alcohol Research, please click here.

Critique 197:  Alcohol consumption and the risk of developing dementia  – 13 April 2017

A number of epidemiologic studies have found that light-to-moderate alcohol intake is associated with a lower risk of developing dementia and/or cognitive decline, while excessive drinking may increase the risk. The authors of the present paper carried out a meta-analysis of the current scientific literature that was based on data from 11 studies with 4,586 cases of all-cause dementia diagnosed among more than 70,000 subjects and two additional analyses of studies of approximately 50,000 subjects each for evaluating the association of alcohol intake with the diagnosis of Alzheimer’s disease or vascular dementia.  Seven studies provided results according to type of alcoholic beverage consumed, while two provided results according to APOE 4 levels.

The conclusions of the authors are that, considering all sources of alcohol, light-to-moderate alcohol consumption was associated with a lower risk of all forms of dementia; the risk was reduced for up to 12.5 g/day (about one typical drink) and increased for consumers of more than 38 g/day (about 3 to 4 typical drinks). However, beverage-specific analyses indicated that the effect was only for wine, and not for consumption of beer or spirits.  For moderate consumers of wine, the risk of dementia was reduced by 40% or more in comparison with that of non-drinkers. Little effect was noted among drinkers of spirits, and heavy beer drinkers appeared to have an increased risk of dementia.  The presence or absence of APOE 4 did not appear to modify the effects.

Forum reviewers considered this to be a very well-done meta-analysis of the current literature on the topic. It was based only on prospective epidemiologic studies of very good quality, and sub-analyses evaluated the separate effects of each type of alcoholic beverage.  While the authors were unable to include the pattern of drinking (binge versus regular moderate) in their analyses, and could not test for previous alcohol consumption among current non-drinkers, Forum members agreed with the primary findings of a J-shaped curve between alcohol consumption and all types of dementia (including vascular dementia and Alzheimer’s disease).

Most of this Forum critique deals with potential mechanisms by which wine consumption may reduce the risk of dementia and/or cognitive decline. In addition to the effects of both alcohol and polyphenols in wine on decreasing atherosclerosis and having beneficial effects on hematological factors (affecting cerebral as well as coronary arteries), there may also be anti-inflammatory effects and direct effects on brain structures that play a role.  Given that the beneficial effects were primarily among wine consumers, this suggests that the polyphenols and other non-alcohol substances in wine (perhaps in interaction with alcohol) may be more important than the alcohol itself in reducing the risk of dementia.

The mechanistic studies described in the paper and in this critique provide considerable support for the epidemiologic findings of less dementia and cognitive decline among moderate drinkers. Forum member agree with the authors of this paper that light-to-moderate wine consumption may help lower the risk of dementia, an increasingly important condition in the world’s rapidly ageing populations.

Reference: Xu W, Wang H, Wan Y, Tan C, Li J, Tan L, Yu JT.  Alcohol consumption and dementia risk: a dose-response meta-analysis of prospective studies.  Eur J Epidemiol 2017;32:31-42. doi: 10.1007/s10654-017-0225-3. Epub 2017.

For the full critique of this paper by members of the International Scientific Forum on Alcohol Research, please click here.

Critique 154:  Effects of changes in alcohol consumption on risk of dementia among elderly women  — 12 January 2015

Reference:  Hoang TD, Byers AL, Barnes DE, Yaffe K.  Alcohol Consumption Patterns and Cognitive Impairment in Older Women.  Am J Geriatr Psychiatry 2014; 22:1663-1667.

A number of prospective studies have shown that moderate drinkers are at lower risk of developing dementia or cognitive impairment than abstainers or heavy drinkers; possible mechanisms of a putative beneficial effect could relate to a reduction in the risk of cerebral atherosclerosis, a direct effect on cognition through the release of acetylcholine in the hippocampus, the antioxidant effects of alcohol and polyphenols, or from the down-regulation of inducible nitric synthase and up-regulation of endothelial nitric oxide synthase.

The present study is based on 1,309 women who were aged 65 years or greater at the beginning of a 20-year follow up, during which they had at least two assessments of cognitive function.  At baseline, 42.1% of the women reported that they were “light” drinkers (>0 – < 3 drinks/week, 13.8% reported “moderate” consumption (3-7 drinks/week), and 3.6% reported “heavy” consumption (> 7 drinks/week).  By the 20th year of follow up, 17.5% of the previously normal women had developed dementia (by several standard tests, a previous diagnosis of dementia, or nursing home residence), and 22.7% had developed mild cognitive impairment (MCI).  Thus, a total of 40.2% of the women had developed some degree of cognitive impairment.

In this paper, there was no suggestion that the small percentage of women (5%) who increased their intake changed their risk of cognitive impairment (fully adjusted OR=1.04, 95% CI 0.56, 1.95), when compared with women who did not change their intake or decreased it only slightly.  However, for women who decreased their intake by > 0.5 drinks/week, the authors suggest that there was an increase in risk of cognitive impairment, with unadjusted results showing an OR of 1.34, 95% CI: 1.05-1.70.  However, with full adjustment for confounders, the effect was attenuated: OR = 1.26, 95% CI 0.98, 1.61; p = 0.07.

Forum members noted that the reasons that some women changed their drinking habits could not be ascertained (as is usually the case in observational studies).  Alzheimer’s dementia has a long prodromal period and latent pathology could precede/contribute to a decrease in drinking.  They were also concerned about the lack of cognitive characterization of the cohort at baseline.  Thus, Forum members had some difficulty in knowing how to interpret the finding of a lack of association of baseline drinking with risk of cognitive impairment 20 years later given that we are not told whether the groups defined on baseline drinking differed from each other in age or other health risk factors.  For those who changed their intake, decreasing drinking by > 0.5 glasses/week may be very different for someone drinking > 7 drinks/week than in someone drinking < 1 drink/week.  It would have been better if the authors somehow took baseline drinking into account when assessing effects of change in drinking.

There was also the concern that any observational study that relates the effects of changes in alcohol intake on the risk of a disease without somehow taking earlier drinking into account may give paradoxical results.  (An example is the relation of obesity to cardiovascular disease; overall, there is an increase in risk for obese individuals but when changes in intake among older people are evaluated, the result is often no effect or even a protective effect: the “obesity paradox.”)  The same has been shown for the relation of usual alcohol intake and changes in intake to other diseases.

Thus, while the analyses were done appropriately, Forum members had concerns about whether the findings presented in this paper justify the wisdom of the authors in stating in their conclusion that “Women in their ninth and tenth decade of life who decrease alcohol use may be at risk of cognitive impairment.”  As one reviewer stated: “Knowing from other studies that light to moderate alcohol consumption is good for the heart and the head, I would not advise elderly people to stop drinking.  However, the conclusions of the authors that this paper shows that decreasing alcohol consumption increases the risk of cognitive impairment in elderly women may be true, but are not justified because the design, analysis, and results of the study do not permit such a statement.”

For the full critique of this paper by members of the International Scientific Forum on Alcohol Research, please click here.

Critique 100:  The effects of moderate drinking on cognitive function and dementia: An update —  15 January 2013

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, is 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.

Reference:  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.

For the full review of this critique by members of the International Scientific Forum on Alcohol Research, please click here.

Critique 081:  Alcohol intake in the elderly affects risk of cognitive decline and dementia  — 22 May 2012

Reference:  Kim JW, Lee DY, Lee BC, Jung MH, Kim H, Choi YS, Choi I-G.  Alcohol and Cognition in the Elderly: A Review.  Psychiatry Investig 2012;9:8-16;  On-line: http://dx.doi.org/10.4306/pi.2012.9.1.8

A well-done review paper on the association between alcohol consumption and cognition in the elderly provides an excellent summary of potential mechanisms by which alcohol may affect cognitive function and the risk of dementia, both adversely and favorably.  Current scientific data indicate that heavy drinking is associated with an increased risk of neurological disease and dysfunction, while regular light-to-moderate alcohol intake seems to be associated with a reduced risk of such dysfunction, including a lower risk of developing Alzheimer’s disease.

At present, the mechanisms by which the moderate intake of wine and other alcoholic beverages reduces the risk of cardiovascular diseases are much better defined than they are for cognition.  Forum members agree with the authors that further research is needed to evaluate a potential role that wine and other alcoholic beverages may play in reducing the risk of dementia.  Forum members also agree that, at present, the specific mechanisms of such putative protection are not well defined, and it would be premature to recommend light-to-moderate drinking for reducing the risk of dementia.  On the other hand, current epidemiologic and biomedical data suggest that most elderly subjects who are responsible and moderate drinkers would not benefit from being advised to stop their alcohol consumption.

For the full critique of this paper by members of the International Scientific Forum on Alcohol Research, please click here.

Critique 076:  Evaluating the association of alcohol intake with cognitive functioning using a Mendelian randomization study design  — 22 March 2012

Reference:  Au Yeung SL, Jiang CQ, Cheng KK, Liu B, Zhang WS, Lam TH, Leung GM, Schooling CM.  Evaluation of moderate alcohol use and cognitive function among men using a Mendelian randomization design in the Guangzhou Biobank Cohort Study.  Am J Epidemiol 2012; pre-publication release. DOI: 10.1093/aje/kwr462

Many observational cohort studies have shown that moderate alcohol use is associated with better cognitive function.  However, since such studies are vulnerable to residual confounding by other lifestyle and physiologic factors, the authors conducted a Mendelian randomization study, using aldehyde dehydrogenase 2 (ALDH2) genotype (AA, GA, or GG) as an instrumental variable in 2-stage least squares analysis.  Cognitive function was assessed from delayed 10-word recall score (n = 4,707) and Mini-Mental State Examination (MMSE) score (n = 2,284) among men from the Guangzhou Biobank Cohort Study (2003–2008).  The authors had previously reported an association between reported alcohol intake and cognitive function  from a larger group of subjects from the same study finding that women reporting occasional alcohol intake and men reporting occasional or moderate intake had better scores related to cognitive function than did abstainers.¹

In the present Mendelian study, the authors found no significant association between groups defined by the ALDH2 genotype (as an “unbiased” estimate of alcohol consumption) and the two measures of cognitive functioning.  A problem with the present analysis is that ALDH2 genotypes explained only 3% of the variance in reported alcohol intake, which weakens the conclusions of the authors.  Further, differences in the predominant type of beverage consumed (rice wine), and probably marked differences in drinking patterns between these subjects and Europeans and Americans, make it difficult to know what the implications of this study are for western industrialized societies.

We agree with the authors that “Causality should be thoroughly verified in a variety of settings using different kinds of evidence, including experimental or genetic studies, rather than relying on simple observations in a particular setting.”  We strongly support future attempts at using Mendelian  randomization studies, hopefully using better instruments for estimating alcohol intake.  On the other hand, as stated by recent evaluations of various study designs for determining causality,³ we appreciate that Mendelian randomization sounds good, but it is not the “Holy Grail.”

Please click here for the full critique of this paper by members of the International Scientific Forum on Alcohol Research.

Critique 053:  An extensive review of the effects of alcohol consumption on the risk of cognitive impairment and dementia  – 25 August 2011

Reference:  Neafsey EJ, Collins MA.  Moderate alcohol consumption and cognitive risk.  Neuropsychiatric Disease and Treatment 2011:7:465–484.

The authors of this paper have carried out an excellent review of the relation of alcohol consumption to the risk of cognitive impairment and dementia.  They reviewed a total of 143 previous publications on the topic. There were 74 studies, based on a total of more than 250,000 subjects, that provided risk estimates for varying levels of alcohol consumption which allowed the investigators to include them in a comprehensive meta-analysis.  These papers were published mainly after 1998, were predominantly among older subjects (92% were ≥ 55 years of age and 70% ≥ 65 years of age), and almost all employed mental status examinations to define cognitive impairment/dementia.

As stated by the authors, “These studies overwhelmingly found that moderate drinking either reduced or had no effect on the risk of dementia or cognitive impairment.”  Overall, in the new meta-analysis based on these studies, the average ratio of risk for cognitive risk associated with moderate drinking of alcohol was 0.77, with nondrinkers as the reference group.  This estimate is close to the estimates of reduction in the risk of cognitive dysfunction (RR of 0.73 and 0.74) seen in other recent selective meta-analyses.  The present study found that both light and moderate drinking provided a similar benefit, but heavy drinking was associated with non-significantly higher cognitive risk for dementia and cognitive impairment.

Forum reviewers of this paper were particularly pleased that the authors attempted to answer a number of specific questions on this topic that have been raised from previous research.  Their results included finding no appreciable differences whether or not “sick quitters” were included in the reference group, little effect from adjustments for other lifestyle factors, and no significant differences between alcohol’s effects on dementia, Alzheimer’s dementia, or vascular dementia (but, based on a small number of studies, no significant reduction in risk of cognitive decline over time).  The investigators concluded that there were no differences between results in men and women.  Their analyses also led to the conclusion that wine is associated with more beneficial effects on cognition than beer or spirits, but the authors caution that these results are based on a limited number of reports, and that many studies show no significant differences according to type of beverage.

Forum reviewers agreed with the conclusions of the authors that “Overall, light to moderate drinking does not appear to impair cognition in younger subjects and actually seems to reduce the risk of dementia and cognitive decline in older subjects.”

For the full critique of this paper by members of the International Scientific Forum on Alcohol Research, please click here.

Critique 036. Alcohol consumption after age 75 associated with lower risk of developing dementia- 7 March 2011

Reference:  Weyerer S, Schaufele M, Wiese B, Maier W, Tebarth F, van den Bussche H, Pentzek M, Bickel H, Luppa M, Riedel-Heller SG, for the German AgeCoDe Study Group (German Study on Ageing, Cognition and Dementia in Primary Care Patients).   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 and Ageing 2011; 0: 1–7; doi: 10.1093/ageing/afr007.

A population-based study of elderly Germans, aged 75 and older, evaluated the association between alcohol consumption and incident overall dementia and Alzheimer dementia over 3 years.  There was good ascertainment of the development of dementia, even among subjects who died during follow up.  Of 3,202 subjects free of dementia at baseline, 217 subjects met criteria of dementia during follow up.  Subjects consuming alcohol had approximately 30% less overall dementia and 40% less Alzheimer dementia than did non-drinking subjects.  Unlike many previous studies showing greater effects of wine on reducing risk of dementia, no significant differences were seen according to the type of alcoholic beverage consumed.  Overall, these results are similar to several previous studies in the very elderly and suggest that moderate drinking is associated with less dementia, even among individuals aged 75 years and older.

For the full critique of this article by the International Scientific Forum on Alcohol Research, please click here.

Critique 014. Moderate drinking, especially of wine, is associated with better cognitive function. 13 August 2010

Reference:  Arntzen KA, Schirmer H, Wilsgaard T,  Mathiesen EB.  Moderate wine consumption is associated with better cognitive test results: a 7 year follow up of 5033 subjects in the Tromsø Study.  Acta Neurol Scandd 2010; Suppl 190:23-29.

A large prospective study of men and women in northern Norway reported that moderate wine consumption was independently associated with better performance on cognitive tests after 7 years of follow up.  There was no consistent association between consumption of beer or spirits and cognitive test results.  The authors also reported that abstinence was associated with significantly lower cognitive performance in women.  As noted by the authors, in any observational study there is the possibility of residual confounding by other lifestyle habits affecting cognitive function, and the present study was not able to adjust for certain ones (e.g., diet, income, or profession) but did adjust for age, education, body mass index, depression, and cardiovascular disease and its major risk factors.

The results of this study support findings from a number of observational, prospective studies that have shown that the moderate consumption of alcohol, especially of wine, may have favorable effects on cognitive function.  Such effects could relate to the presence in wine of a number of polyphenols and other substances that reduce the risk of cognitive decline with ageing.  Mechanisms that have been suggested for such protection against cognitive dysfunction include effects on atherosclerosis, coagulation, inflammation, as well as direct neuroprotective effects.

For the detailed critique of this paper by the International Scientific Forum on Alcohol Research, click here.

Critique 008.  Further evidence that moderate alcohol consumption may play a role in the prevention of Alzheimer’s Disease. 13 June 2010

Reference :  García AM, Ramón-Bou N, Porta M.   Isolated and joint effects of tobacco and alcohol consumption on risk of Alzheimer’s Disease.   Journal of Alzheimer’s Disease 2010;20:577–586. (DOI 10.3233/JAD-2010-1399).

In a case-control study from Spain on the effects of smoking and alcohol use on the risk of Alzheimer’s Disease (AD), the authors found that the risk of AD was unaffected by any measure of tobacco consumption.  On the other hand, alcohol consumers showed a 47% lower risk of developing AD than did never consumers, with effects mainly among women and among never smokers.  No differences were noted by type of alcoholic beverage consumed.  The authors conclude that mean daily total consumption of alcohol showed increasingly protective dose-response relationships in women.

The numbers in this analysis were rather small, and there is always the possibility of confounding by other lifestyle factors.  Still, the study supports a number of previous epidemiologic studies showing a lower risk of developing AD for moderate consumers of alcohol.

For the full critique of this paper by the International Scientific Forum on Alcohol Research, please click here: Critique 08.