Two new studies linking soft drinks – both regular and diet – to brain changes, stroke and dementia could make those who love the drinks to rethink their hydration choices.
In onestudy, researchers found that people who frequently consume sugary beverages such as soft drinks, sports drinks and fruit juices are more likely to have poorer memory and smaller brain volumes -- both overall and in their hippocampus, an area of the brain important for memory.
The other study found that diet drinks aren’t much better.
That research found that drinking one diet soft drink or more each day is linked to a tripled risk of having a stroke or developing dementia, compared to avoiding the drinks.
The authors caution that, while their studies were large and lengthy, they don’t prove that soft drinks lead to memory or brain problems; they only found links between the drinks and brain effects.
Still, even the authors of the diet drink study say were surprised with their findings, but say they are noteworthy, given that so many people choose diet pop over regular, believing they are a healthier alternative.
Both sugar and artificially-sweetened drink consumption has been linked in previous research to “cardiometabolic risk factors,” such as high blood pressure, high blood sugar, and abnormal cholesterol – all of which increase the risk of stroke and dementia.
The two studies appear separately in the journals Alzheimer's & Dementia and the journal Stroke. Both relied on data from the Framingham Heart Study, which began in Massachusetts in 1948 to identify the risk factors for heart disease and has been extended several times since.
Participants were asked over several intervals to report their daily beverage intake. They were also examined using MRIs (magnetic resonance imaging) and cognitive testing to measure their thinking and memory.
People who frequently drank sugary drinks were found to be more likely to have poorer memory and smaller brain volumes.
Those who drank at least one artificially-sweetened beverage a day were almost three times as likely to have an ischemic stroke (the most common type), and 2.9 times as likely to develop Alzheimer's disease dementia.
The authors say it’s possible that the people who choose to drink diet drinks every day are already at risk of health problems. For example, the participants who most frequently drank diet soft drinks were also more likely to be diabetic -- which is in itself a risk factor for stroke and dementia.
Still, even when the researchers excluded diabetics from the study, they found a link between drinking diet soda and the brain risks.
Matthew Pase, a senior fellow in the department of neurology at Boston University School of Medicine, and the lead author of the diet drinks study, says it’s important to note that the absolute risk for any one person who drinks diet pop is low. Of the 2,888 participants the study followed, there were only 97 cases of stroke and 81 cases of dementia.
“Even if someone is three times as likely to develop stroke or dementia, it is by no means a certain fate,” he said in a statement.
“In our study, three per cent of the people had a new stroke and five per cent developed dementia, so we're still talking about a small number of people developing either stroke or dementia.”
Although the authors say their findings spotted an intriguing connection between dementia, stroke and diet drink consumption that will need to be explored further in other studies.
Dr. Ralph Sacco, former president of the American Heart Association and the chairman of the neurology department at the University of Miami, said the latest findings are consistent with previous studies that also suggested associations between artificially-sweetened drinks and dementia and stroke risks.
“I think, like everything, we need more studies to confirm whether the association is true and causal or whether the association is caused by something else,” he told CTV News.
“I say: drink water or flavoured water for now and take a concerted effort to avoid, for now, artificially sweetened beverages until we can figure out more of these results,” he said.
With files from CTV's medical specialist Avis Favaro and producer Elizabeth St. Philip