By Lisa Rapaport
Most older adults who have one or two drinks a day are no more likely to develop cognitive decline or dementia than their peers who drink only rarely, a recent study suggests.
The researchers followed 3,021 adults aged 72 and older for an average of six years. At the start, most were free of cognitive issues; 473 of them had mild cognitive impairment.
By the end of follow-up, 512 people had developed dementia, including 348 cases of Alzheimer's disease.
For people without any cognitive issues at the start of the study, there wasn't a meaningful difference in the risk of developing dementia based on how much they drank.
When participants started out with mild cognitive impairment, people who had more than 14 drinks a week were 3.5 times more likely to develop dementia than those who had less than one drink weekly, but people who abstained entirely were also at increased risk.
"Our findings provide some reassurance that alcohol consumed within recommended limits was not associated with an elevated risk of dementia among older adults with normal cognition," said Manja Koch, lead author of the study and a nutrition researcher at the Harvard T.H. Chan School of Public Health in Boston.
"Nevertheless, patients should talk to their physicians about alcohol intake, who can provide individualized risk assessments," Koch said by email. "Given the clear risks and costs of its overuse, and the uncertain balance of risks and benefits of moderate use, individuals who choose to drink should do so in moderation."
For the study, researchers grouped participants by alcohol consumption levels: none; less than one drink a week; one to seven drinks a week; 7.1 to 14 drinks a week; and more than 14 weekly drinks.
Overall, 1,286 people, or about 43%, said they didn't drink at all. Another 466 individuals, or 15%, said they had less than one drink a week; 689, or 23%, had one to seven drinks weekly. About 9% of the participants said they had between 7.1 and 14 drinks weekly and roughly 10% had more than 14 drinks a week.
People with mild cognitive impairment at the start of the study did appear to have a lower risk of dementia when they had 7.1 to 14 drinks a week than when they had up to seven weekly drinks. Daily drinking in smaller amounts was also associated in this group with lower risk compared to infrequent bouts of drinking larger amounts.
The study, online September 27 in JAMA Network Open, was not designed to determine whether or how cognitive impairment might influence drinking choices or how drinking might directly affect cognitive impairment.
One limitation of the study is that researchers relied on participants to truthfully report how much they drank. Another is that there were few heavy drinkers, making it hard to draw firm conclusions about the effects of excessive drinking on dementia risk, the study team notes.
Also, many other lifestyle habits that are connected to drinking habits might influence the risk of dementia, said Clive Ballard, a professor of age-related diseases at the University of Exeter Medical School in the UK.
"We need to interpret these findings with caution," Ballard, who wasn't involved in the study, said by email. "It's a relatively small study, and it's really difficult to compare a group of drinkers to those who are teetotalers or drink very little, because it's hard to control for a range of different cultural and health issues that may have an effect."
JAMA Netw Open 2019.
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