The results of a new study point to a correlation between regular but moderate drinking in older adults, and a reduced risk of cognitive impairments. This research was based on a cohort study of middle-class adults in the United States.
According to data from the National Institute on Alcohol Abuse and Alcoholism (NIAAA), excessive alcohol consumption is responsible for around 88,000 deaths each year in the United States. However, the 2015 scientific report of the U.S. Department of Agriculture shows that moderate drinking can have several health benefits, including a decreased risk of heart disease and diabetes.
A new study led by scientists from the University of California San Diego School of Medicine in La Jolla has now found a correlation between moderate drinking on a regular basis and prolonged cognitive health, as well as longevity.
Senior study author Dr. Linda McEvoy explains that their research is, as far as they are aware, the first of its kind; it specifically takes into account the frequency of alcohol intake in an older population.
"This study is unique because we considered men and women's cognitive health at late age and found that alcohol consumption is not only associated with reduced mortality, but with greater chances of remaining cognitively healthy into older age," she says.
Dr. McEvoy and her colleagues have published their findings in the current issue of the Journal of Alzheimer's Disease.
Data collected from uniform cohort
The researchers worked with data collected from 1,344 adults recruited in the Rancho Bernardo Study, a prospective cohort study of residents from a middle-class Californian community. Of the participants selected for the current research, 728 were women and 616 were men.
It should also be noted that the cohort the researchers worked with was relatively uniform; the participants were almost all white (99.4 percent) and middle- or upper-middle class.
The study was conducted over a period of 29 years, until December 2013. The participants' cognitive health was assessed at baseline, and then again once every 4 years.
To be eligible, participants were required to have "the potential to reach age 85 during the follow-up period." Those who did reach this age during the study had to have their cognitive health status reassessed within 2 years from their 85th birthday.
Moderate drinkers cognitively healthy
All the participants were asked to provide information about their alcohol consumption patterns through a standardized questionnaire. Drinking was labeled as "moderate," "heavy," or "excessive" according to NIAAA guidelines adjusted for age and biological sex.
Moderate alcohol consumption added up to, at most, one standard drink per day for women of all ages and men aged 65 and older, or up to two drinks per day for men under 65. It was defined as "heavy" in the case of up to three drinks per day for men aged 65 and older and women of all ages, or up to four drinks per day for men under 65.
Finally, "excessive" consumption counted more than three drinks per day for men aged 65 and older and women of all ages, or more than four drinks per day for men under 65.
Regarding time patterns, participants could choose from being completely drink-free, drinking up to twice a month, drinking up to four times per week, or drinking between five and seven times per week.
According to Dr. McEvoy, "There were very few individuals in our study who drank to excess, so our study does not show how excessive or binge-type drinking may affect longevity and cognitive health in aging."
What the study did find was that moderate and heavy drinkers were more likely to attain what the researchers call "Cognitively Healthy Longevity" - that is, they retained cognitive health for longer. They were also likely to have a longer lifespan.
Specifically, when compared with non-drinkers, participants who had reported a daily or almost daily intake of alcohol had a significantly increased likelihood of maintaining their cognitive health into old age.
Contrasts and considerations
While the researchers adjusted their results for relevant factors, including smoking or excessive weight gain, they admit that their analysis was based solely on statistical relationships.
The researchers caution that it is not clear whether or not there is an actual causal link between frequent drinking and better cognitive health or longevity. They emphasize that their findings should not encourage people to take up drinking, or to increase their alcohol intake.
"This study shows that moderate drinking may be part of a healthy lifestyle [...] However, it is not a recommendation for everyone to drink. Some people have health problems that are made worse by alcohol, and others cannot limit their drinking to only a glass or two per day. For these people, drinking can have negative consequences."
Lead author Erin Richard, University of California San Diego School of Medicine
In their discussion of the findings, the researchers reported that their results are in stark contrast with those of a Norwegian population study from 2015, which found that frequent drinking was linked to a higher risk of dementia.
However, the authors note that "frequent drinking" was, in that case, defined as the intake of five or more drinks over a 2-week period and referred to completely different alcohol consumption patterns.
The team also emphasizes that the Norwegian population study did not clarify whether the alcohol intake was spread over the 14 days or concentrated in 1 or 2 days, which might also have impacted the correlation.