Heavy use of six popular sweeteners was tied to 62% faster cognitive decline over eight years

Adults who consumed the most low- and no-calorie sweeteners saw their thinking and memory decline 62% faster over about eight years than adults who consumed the least, according to a study of 12,772 Brazilians. Six sweeteners were linked to the faster decline: aspartame, saccharin, acesulfame-K, erythritol, sorbitol and xylitol. The study is observational, so it shows an association and cannot establish that the sweeteners caused the change.

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Six sweeteners, and the one that showed nothing

Claudia Kimie Suemoto of the University of Sao Paulo led the work, published in the journal Neurology. The team tracked seven sweeteners in all, and the seventh, tagatose, showed no link to cognitive decline. ScienceDaily is careful to add that this does not make tagatose protective or safer than the others. Sorbitol had the highest average intake, at 64 milligrams a day. One timing note: ScienceDaily carried its summary on Oct. 29, 2026, while the paper itself appeared in Neurology’s September 2025 issue.

Intake was sorted into three groups. The lowest averaged 20 milligrams a day and the highest 191 milligrams, which the authors compare to the aspartame in about one can of diet soda. ScienceDaily’s summary of the American Academy of Neurology release puts the highest group’s decline at 62% faster, equal to about 1.6 additional years of cognitive aging, and the middle group’s at 35% faster, about 1.3 years. The academy’s own news release, which it corrected on July 30, 2026, lists 63% and 36% for the same comparisons, so the figures differ by a point depending on which version is read.

Under 60 and with diabetes: where the link was strongest

Participants took cognitive tests at the start, the midpoint and the end, covering verbal fluency, working memory, word recall and processing speed. Results were adjusted for age, sex, high blood pressure and cardiovascular disease. Among adults under 60, higher intake was linked to faster declines in verbal fluency and overall cognition, with no similar association in people over 60. The association was also stronger in people with diabetes than in those without, and Suemoto noted that people with diabetes are more likely to use sweeteners as sugar substitutes.

Suemoto said the findings suggest certain sweeteners may have negative effects on brain health over time, and that more research is needed to confirm them.

Outside experts and an industry group respond

Medical News Today sought comment from people outside the study. Kamal Wagle, a geriatric specialist at Hackensack University Medical Center in New Jersey, said the study shows a link, not a cause, and does not prove that sweeteners are responsible for cognitive decline. He called for controlled trials and research into biological mechanisms, and asked why the link appeared only in people under 60. Carla Saunders, president of the Calorie Control Council, an industry group, said the study has notable limitations, including reliance on self-reported dietary data collected only at baseline. She argued the findings could mislead people with diabetes who rely on these sweeteners, which the article notes the American Diabetes Association recommends.

Monique Richard, a registered dietitian who owns Nutrition-In-Sight, read the results as a signal for caution rather than conclusive evidence, according to the same report, and recommended whole foods with sparing use of sweeteners. Suemoto herself told Medical News Today the study cannot prove causation, and that the 1.6-year figure is a statistical translation, not a sign that participants felt older.

Reading the 62% correctly takes some care. It compares the pace of decline in overall thinking and memory scores between the highest and lowest of three intake groups, after adjustment, and the gap between those groups was roughly 171 milligrams a day on average. The authors translated the result into about 1.6 years of extra cognitive aging as a way of making the statistics easier to interpret. A person in the top group did not necessarily lose that time, and a person in the bottom group was not protected from decline.

The limits are spelled out in the release. The study did not cover every artificial sweetener on the market, diet data came from participants’ recall of the previous year and may be inaccurate, and other factors could explain the association despite statistical adjustment. The cognitive estimates reflect changes in test performance, not direct measures of biological brain aging, and Suemoto noted the 1.6-year figure does not mean people feel older. The full analysis is in the Neurology paper.

The study was funded by Brazil’s Ministry of Health, the Ministry of Science, Technology and Innovation, and the National Council for Scientific and Technological Development. A companion commentary in the same issue, Thomas Monroe Holland’s The Dark Side of Sweet, accompanied the paper. What remains untested is whether the sweeteners themselves alter brain function, why some groups appear more affected, and whether alternatives such as applesauce, honey, maple syrup or coconut sugar behave differently, questions the researchers say future work must answer.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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