Claim: Diet soda causes dementia

This is crazy. Really.

This study is just more of the junk epidemiology that we have debunked for the past 21 years. It has all the usual pitfalls (i.e., poor quality data, statistical malpractice, no biological plausibility, etc.) but I spotlight it because of this: The soda intake data is derived from patient recall (self-report) — not very reliable to start with but here compounded by subjects with… dementia. That’s the ticket, ask people with memory problems how much soda they consumed.

The media release and abstract are below.


Diet drinks and possible association with stroke and dementia
Current science suggests need for more research


DALLAS, April 20, 2017 — Drinking at least one artificially sweetened beverage daily was associated with almost three times the risk of developing stroke or dementia compared to those who drank artificially-sweetened beverages less than once a week, according to new research in the American Heart Association’s journal Stroke.

The authors caution that the long-term observational study was not designed or able to prove cause and effect, and only shows a trend among one group of people.

“Our study shows a need to put more research into this area given how often people drink artificially-sweetened beverages,” said Matthew Pase, Ph.D., a senior fellow in the department of neurology at Boston University School of Medicine, Swinburne University of Technology in Melbourne, Australia, and the Framingham Heart Study.

“Although we did not find an association between stroke or dementia and the consumption of sugary drinks, this certainly does not mean they are a healthy option. We recommend that people drink water on a regular basis instead of sugary or artificially sweetened beverages.”

The researchers analyzed the Framingham Heart Study Offspring Cohort of 2,888 people, primarily Caucasian, over the age of 45 for the stroke study and 1,484 people over the age of 60 for the dementia arm of the study. Over a period of seven years, the researchers reviewed what people were drinking at three different points in time. Participants reported their eating and drinking habits by responding to food frequency questionnaires. The researchers then followed up with the study subjects for the next 10 years to determine who developed stroke or dementia, then compared the dietary information to the risk of developing stroke and dementia over the course of the study. The data collected did not distinguish between the types of artificial sweeteners used in the beverages.

At the end of the 10-year follow-up period, the researchers noted 97 cases (3 percent) of stroke, 82 of which were ischemic (caused by blockage of blood vessels), and 81 (5 percent) cases of dementia, 63 of which were diagnosed as Alzheimer’s disease.

The researchers used statistical models, adjusted for various risk factors such as age, sex, caloric intake, education, diabetes mellitus and the presence of a variant of the Alzheimer’s risk gene apolipoprotein E, to determine potential links between artificially-sweetened drink consumption and the risk of stroke or dementia. They found that people who drank at least one artificially-sweetened beverage a day were three times as likely to develop ischemic stroke and 2.9 times as likely to develop Alzheimer’s disease dementia.

Although the prospective nature of the study design increases the reliability of its findings, there are limitations. The participants were overwhelmingly white, and it is possible that ethnic preferences may influence how often people select sugary or artificially sweetened drinks, Pase said. People did not drink sugary sodas as often as diet sodas, which Pase said could be one reason the researchers did not see an association with regular soda since the participants may have been health conscious and just not consuming them as frequently. The main limitation, Pase said, is the important point that an observational study like this cannot prove that drinking artificially-sweetened drinks is linked to strokes or dementia, but it does identify an intriguing trend that will need to be explored in other studies.

“Even if someone is three times as likely to develop stroke or dementia, it is by no means a certain fate,” Pase said. “In our study, three percent of the people had a new stroke and five percent developed dementia, so we’re still talking about a small number of people developing either stroke or dementia.”

According to an accompanying editorial, the current body of scientific research is inconclusive regarding whether or not drinking artificially sweetened beverages can actually lead to stroke, dementia or other cardiovascular conditions. However, there are a growing number of population based studies, such as this study by Pase,, that show associations between frequent consumption of artificially sweetened beverages and undesirable effects on blood vessels throughout the body. This suggests that it may not be advisable to substitute or promote artificially sweetened drinks as healthier alternatives to sugar-sweetened drinks. “Both sugar and artificially sweetened soft drinks may be hard on the brain,” said senior editorial author Ralph Sacco M.D., a former president of the American Heart Association and the chairman of the Department of Neurology at the Miller School of Medicine at University of Miami in Florida.

“We know that limiting added sugars is an important strategy to support good nutrition and healthy body weights, and until we know more, people should use artificially sweetened drinks cautiously. They may have a role for people with diabetes and in weight loss, but we encourage people to drink water, low-fat milk or other beverages without added sweeteners,” said Rachel K. Johnson, Ph.D., M.P.H., R.D., past chair of the American Heart Association’s Nutrition Committee and professor of nutrition at the University of Vermont.


12 thoughts on “Claim: Diet soda causes dementia”

  1. “artificially-sweetened beverages” is such a broad food group that it is meaningless to use for a prospective correlation study. This is a classic data dredge and goes like this:

    We have three food intake questionnaires over a 7 year period, followed by a 10 year follow-up of instances of diseases. Let’s look for anything we can find a correlation with. Hmm, nothing because there are so many groups and so few people that the stats are too small. OK, let’s group a few things together (like unsweetened beverges, for example) and create five or six different consumption classes to see what we can come up with. Ahh, so if we lump any level of regular unsweetened beverage consumption we can finally find something which comes out as significant. Phew, we have something to publish.

    Next is the journal, they want to get some publicity so they write a press release without any of the caveats in the paper and send it out to the press. The journalists have a deadline and need to fill column inches so they just regurgitate the press release with a minimum of inpout (even if they knew anything about the stats, they haven’t got the time or inclination to critique the claims) and then a sub-editor looks for a scary headline to get people to click on it on the website.


  2. Rob Karl It still junk, it looks like they had no controls as to the social, genetic, overall health of the group, yep great study you ask people to participate and yet do not filter what you get you don’t group people based of large number of risk factors and only look at one risk factor, and somehow you study means something? Add in a really small sample size and somehow this is gospel. Yea and Rob do you want to by a bridge, I have one in Brooklyn I can sell you.

  3. The study covered 17 years. The diet survey covered 7 years before anyone developed dementia. Researchers returned 10 years after the diet survey to observe health status.

  4. And what is the artificial sweetener implicated? Overweight and obese people turned to diet well before much of the rest of the public, factors known to increase chance of stroke. Abuse of statistics, irresponsible science reporting.
    “Although we did not find an association between stroke or dementia and the consumption of sugary drinks,…”
    The authors recommend drinking water, but this kind of information is likely to make someone going for a soda raech for the sugary option, the harms fom which are well documented. Who paid for this study?

  5. “The data collected did not distinguish between the types of artificial sweeteners used in the beverages.” Because the chemical composition of one sweetener couldn’t possibly be more, or less, effective or harmful than other sweeteners.

  6. This is, indeed, crazy. One might even call it demented. It does nicely illustrate why one should never throw their money away by gifting to the American Heart Association or any of the other organized lobbies that solicit funds for “research” on any number of diseases. They promote this kind of junk in order to justify their existence and their generous salaries.
    One often sees obituary notices that end with a statement such as “in lieu of flowers, please donate to the American Cancer Society or the American Heart Association or some other like-minded “charitable” research organization. I have always told people not to waste their money. At least buying flowers has some marginal benefit to the economy whereas their donations to “health” related organizations are entirely wasted.

  7. Well substituting diet soda for a glass of healthy red wine with your steak or burger is obviously a poor choice. However, substituting water from Lansing, Michigan for any beverage is a terrible choice. Any study based on recall is totally flawed. They should publish the actual questions and how they were answered. There seems to be a small war on non-sugar sweeteners by the same people who totally buy into human caused global warming, pesticide fear and any fear of chemicals, which by the way make up everything in the universe.

  8. Maybe people should read the study before they comment on it, including the OP. It does not make the simplistic claim that diet soda causes dementia. What is says is that drinking one or more diet sodas a day has been found to be associated with a higher risk of stroke and dementia, whereas naturally sweetened beverages were not found to be so associated. Including people who drink 25 diet sodas a day in the cohort does not undermine the study, because nobody is claiming that drinking just one, or two, or three or any specific number of diet sodas a day causes anything. Again, the finding was that drinking ONE OR MORE diet sodas a day is ASSOCIATED with an increased risk of stroke and dementia. The notion that the study is unreliable because people with dementia were asked to report how many diet sodas they drank is also false, as the study involved people with pre-clinical Alzheimer’s.

  9. “…is derived from patient recall (self-report) — not very reliable to start with but here compounded by subjects with… dementia.”

    LOL, great catch!

    It is amazing the drek that gets published these days. and it apparently took eight doctorates to come with this example.

  10. Good grief! “Drinking at least one…” also includes the cohort that drinks 25 each day, making the study and its conclusions absolutely meaningless.

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