Adults who consumed larger amounts of several low- and no-calorie sweeteners experienced faster declines in memory and thinking skills in a long-term Brazilian study, but researchers caution that the findings do not prove the sweeteners caused the changes.
The study followed 12,772 adults for an average of eight years. Participants were 52 years old on average and completed a food-frequency questionnaire describing what they had eaten and drunk during the previous year. Researchers tested memory, verbal fluency, working memory and processing speed at three points.
The seven sweeteners examined were aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol and tagatose. They are found in products such as diet drinks, flavored water, yogurt, low-calorie desserts and tabletop sweeteners.
Participants in the lowest-consumption group averaged 20 milligrams a day across the sweeteners studied. The highest group averaged 191 milligrams. After researchers adjusted for factors including age, sex, high blood pressure and cardiovascular disease, the highest group showed a 62% faster decline in overall cognition than the lowest group. Researchers described the difference as roughly equivalent to 1.6 years of additional cognitive aging.
Association was not the same for everyone
The middle-consumption group showed a 35% faster decline than the lowest group, an estimated equivalent of 1.3 years of aging. The association was stronger among participants with diabetes and appeared in people younger than 60. Researchers did not find a significant link in participants over 60.
Six of the sweeteners, aspartame, saccharin, acesulfame-K, erythritol, sorbitol and xylitol, were associated with faster decline in overall cognition, particularly memory. Tagatose was not.
The results should be interpreted cautiously. This was an observational study, not a randomized experiment. Participants reported their own diets, which can introduce memory and measurement errors. People who consume more sweeteners may also differ in health, diet or lifestyle in ways statistical adjustments cannot fully capture.
The research did not include every sweetener on the market, so its results cannot be applied to all sugar substitutes. The peer-reviewed article was published in Neurology in September 2025 and later received a correction to some confidence intervals. The general conclusion remained an association requiring further study.
The findings do not mean people should replace sweeteners with unlimited sugar or abruptly change a diabetes-management plan. Anyone using sugar substitutes for a medical reason should discuss major dietary changes with a physician or registered dietitian familiar with their health history.
Sources: The Hill, the American Academy of Neurology, the peer-reviewed study in Neurology and PubMed.
