Certain Patterns of Alcohol Use Up Risk for Cognitive Decline

Is the Public Getting the Wrong Message About Drinking?

Caroline Cassels

July 26, 2012

July 26, 2012 (Vancouver, British Columbia) — Despite a body of research and ensuing public health messages suggesting that alcohol consumption can benefit health, including cognition, 2 large studies suggest that particular patterns of drinking may actually increase the risk for cognitive decline in older individuals.

Both studies were presented here at the Alzheimer's Association International Conference (AAIC) 2012.

The first study, conducted by investigators from the University of Exeter in the United Kingdom, showed that over an 8-year period, heavy episodic drinking, commonly known as binge drinking, in a large cohort of older adults was associated with up to a 2.5-fold increased risk for cognitive decline and memory loss and that this effect was dose dependent.

"Those who were binge drinkers were much more likely to experience the greatest level of cognitive decline. Those who reported binge drinking once a month or more had an odds ratio of cognitive decline of about 1.5, and for those who reported binge drinking twice a month or more, the odds ratio was about 2.5," lead investigator Iain A. Lang, PhD, told Medscape Medical News.

Dr. Iain A. Lang

In the second study, investigators at the University of California, San Francisco, found that moderate alcohol consumption in a cohort of older women did not protect cognitive function and that switching from nondrinking to drinking status in later life significantly increased the risk for cognitive decline.

"Women who started drinking [in later life] were 3 times more likely to develop cognitive impairment compared to nondrinkers," study investigator Tina Hoang, MSPH, Veterans Health Research Institute, San Francisco, told conference delegates.

Tina Hoang

Challenging Conventional Wisdom

Current public health messages about drinking, said Dr. Lang, are based on the research to date, which suggests that moderate levels of alcohol use are beneficial to physical and cognitive health, whereas heavy drinking is harmful.

"The established wisdom about alcohol use and both cardiovascular health and cognitive health is that there is a J-shaped relationship such that moderate drinking is safe and possibly protective, whereas nondrinking and heavy drinking are both bad for you.

"Starting from this position ignores the pattern of drinking and presumes that people who have 1 drink a day every day are moderate drinkers. But in fact, people drink in all kinds of ways, and previous research hasn't really teased out cognition and whether it makes a difference if you drink 7 drinks in 1 day and none the rest of the week vs 1 drink every day," he said.

Dr. Lang added that the main motivation for conducting this study was that binge drinking and its potential impact on cognition have not been examined in any substantive way before.

"Binge drinking is more commonly thought of as a concern in younger adults," he said.

To assess the effects of binge drinking on cognition and mood in older individuals, the investigators analyzed data on 5075 persons aged 65 years or older who were participants in the Health and Retirement Study, a biennial, longitudinal, nationally representative survey of older adults in the United States.

Baseline data were collected in 2002, and participants were followed for up to 8 years. Information on levels of overall alcohol consumption as well as the level of binge drinking — defined as consumption of 4 or more drinks on 1 occasion — was assessed.

Study outcomes included change in cognitive function and memory, as assessed using the Telephone Interview Survey of Cognitive Status.

Need to Change the Message?

Binge drinking once a month or more was reported by 8.3% of men and 1.5% of women, and binge drinking twice a month or more was reported by 4.3% of men and 0.5% of women.

After adjusting for age, sex, mean number of drinks per day, baseline cognitive function score, race, education level, household wealth, and smoking status, the investigators found that older individuals who reported binge drinking twice per month or more had the greatest risk of a 10% decline in cognitive function over the study period (odds ratio [OR], 2.47; 95% confidence interval [CI], 1.31 - 4.60).

This group also had more than a 2.5-fold increased risk for memory decline (OR 2.49, 95% CI, 1.19-5.21).

In participants who reported binge drinking once per month or more, the odds ratio of being in the group experiencing the greatest decline in cognitive function was 1.62 (95% CI, 0.99 - 2.65). The odds ratio of memory decline in this group was 1.27 (95% CI, 0.71 - 2.28).

Outcomes were similar in men and women.

Study coauthor David Llewellyn, PhD, described the findings as "thought-provoking" and said they indicate that there may be a need to fine-tune current public health messages about moderate alcohol use as well as patterns of drinking and the potential impact on cognitive health.

Dr. David Llewellyn

The message that moderate drinking is beneficial is popular among the public. However, he noted, this message is potentially "quite dangerous, because potentially we are promoting something that if done in the wrong way could potentially be quite harmful," Dr. Llewelyn told Medscape Medical News.

20-Year Study

In the second study, researchers also looked at patterns of alcohol consumption over time, including in very late life, and its relationship to cognitive status.

The investigators note that it is unclear whether moderate alcohol consumption has an impact on cognitive impairment in late life, with some studies suggesting a protective effect.

The prospective cohort study included 1306 women aged 65 years and older who were followed for 20 years. Using self-report, the investigators assessed current and past alcohol use at baseline. Current use was reassessed at midpoint (years 6 and 8) and late phases (years 10 and 16) of follow-up.

At year 20, participants were assessed for clinically significant mild cognitive impairment (MCI) and dementia via an expert panel.

At baseline, 40.6% of study participants were nondrinkers, 50.4% were light drinkers (0 - 7 drinks per week), and 9.0% were moderate drinkers (7 - 14 drinks per week). Heavy drinkers (14 drinks or more per week) were excluded from the study.

The investigators found that women who reported drinking more in the past than at baseline were at increased risk of developing cognitive impairment (adjusted OR [aOR], 1.30; 95% CI, 1.02 - 1.65). Moderate drinkers at baseline or at midpoint had similar risk for cognitive impairment compared with nondrinkers. However, moderate drinkers in the late phase were more likely to develop cognitive impairment (aOR, 1.62; 95% CI, 1.14 - 2.32).

Mechanisms Unclear

Women who changed from nondrinking to drinking during the follow-up period also had an increased risk for cognitive impairment (aOR, 3.07; 95% CI, 1.39 - 6.76). Transitioning from drinking to nondrinking over time was not associated with cognitive impairment.

According to Hoang, the findings indicate that it is important not only to screen older adults for adverse drinking and alcohol abuse but also to examine the history of past use and possible changes that may be associated with cognitive impairment.

The study also suggests that moderate alcohol use may not be protective in the oldest old, suggesting a need for more research to better understand the impact of alcohol use at different stages of life.

Although the underlying mechanisms for the study findings are unclear, there are several possibilities, said Hoang.

For example, she said, it may be that alcohol exerts different effects across the life course and that as people age, they may be taking more medications and that there are interactions between alcohol and prescription medications.

Genetic factors may also play a role. Several studies have looked at the differences according to apolipoprotein E (APOE) genotype, but again, the findings have been inconsistent, with some suggesting a protective effect in individuals without the APOE-4 allele and others showing the opposite.

On the other hand, she added, "it may just be that older adults are more vulnerable to the effects of alcohol use."

More Research Needed

Commenting on the findings of both studies, William Thies, PhD, Alzheimer's Association chief medical and scientific officer, said the findings further the knowledge base regarding alcohol use and its impact on cognition.

Dr. William Thies

However, he said, more research is needed.

"The many dangers of misuse of alcohol, and some of its possible benefits, have been widely reported, and there needs to be further clarification by the scientific community," Dr. Thies said in a statement.

"Certainly no one should start drinking in order to reduce Alzheimer's risk, as these 2 new reports attest," he added.

Dr. Thies also called for "longer-term studies in larger and more diverse populations, and we need more funding to make that happen."

Dr. Lang, Tina Hoang, and Dr. Thies have disclosed no relevant financial relationships.

Alzheimer's Association International Conference (AAIC) 2012. Abstracts O4-08-06, O4-08-05. Both presented July 18, 2012.


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