Artificial Sweeteners Linked to Faster Cognitive Decline in Eight-Year Study

Researchers tracking nearly 13,000 adults over eight years found that consumption of popular artificial sweeteners was associated with faster declines in memory and mental sharpness, with the effect particularly pronounced among younger adults and those with diabetes. The study, published in the journal Neurology by the American Academy of Neurology, examined seven common sugar substitutes used in diet sodas, flavored waters, yogurt and ultra-processed foods.

The Study's Scope and Findings

Scientists from the University of São Paulo, Brazil, monitored 12,772 adults with an average age of 52, conducting cognitive assessments at the beginning, midpoint and end of the eight-year period. Participants completed detailed food questionnaires at the start, allowing researchers to categorize them into consumption groups based on their total sweetener intake.

Those consuming the highest amounts averaged 191 milligrams daily, roughly equivalent to the sweetener content in a single can of diet soda. The lowest consumption group averaged 20 milligrams per day. Adults in the highest intake category showed cognitive decline progressing 62 percent faster than those in the lowest group—an acceleration equivalent to approximately 1.6 years of additional brain aging.

The cognitive tests measured verbal fluency (the ability to quickly retrieve words), working memory, word recall and processing speed. Six of the seven sweeteners studied showed associations with faster cognitive decline: aspartame, saccharin, acesulfame K, erythritol, xylitol and sorbitol. Tagatose was the sole exception. Sorbitol showed the highest average daily consumption among individual sweeteners at 64 milligrams.

Important Caveats and Risk Groups

Researchers emphasized that the findings demonstrate association rather than direct causation, meaning other factors could contribute to the observed patterns. The connection was strongest among adults younger than 60 and individuals with diabetes, though the mechanism remains unclear.

Study author Claudia Kimie Suemoto noted that while low- and no-calorie sweeteners are widely promoted as healthier alternatives to sugar, the evidence suggests certain formulations may negatively affect brain health over extended periods. The research does not establish that sweeteners directly cause cognitive decline but indicates a measurable correlation worthy of further investigation.