Summary: A large Brazilian study of nearly 13,000 adults found that higher intake of certain low- and no-calorie artificial sweeteners was associated with faster declines in memory and thinking over eight years. The association was strongest in participants with diabetes and in adults under 60. The research highlights potential long-term brain-health concerns tied to some common sugar substitutes, though it does not establish direct causation.
Researchers observed a clear difference between specific sweeteners: aspartame, saccharin, acesulfame-K, erythritol, xylitol and sorbitol were linked to faster cognitive decline, while tagatose showed no association. These sweeteners frequently appear in ultra-processed foods and beverages such as diet sodas, flavored waters, energy drinks, yogurt and low-calorie desserts, and are also sold as standalone sugar substitutes.
Key Facts
- Faster decline: Participants with the highest combined intake of artificial sweeteners experienced a 62% faster drop in overall cognitive performance over eight years—roughly equivalent to 1.6 years of additional aging.
- Diabetes link: The association with accelerated decline was more pronounced among people with diabetes, a group that commonly uses sweeteners as sugar alternatives.
- Not all sweeteners equal: Tagatose showed no measurable link to cognitive decline, while several other sweeteners were associated with declines in memory and verbal fluency.
Source: AAN
Overview
Published in the September 3, 2025 issue of Neurology, this prospective study evaluated the relationship between consumption of low- and no-calorie sweeteners (LNCSs) and cognitive change. The analysis encompassed seven sweeteners and tracked participants’ diet and cognitive performance over three study waves spanning approximately eight years.
Lead author Claudia Kimie Suemoto, MD, PhD, of the University of São Paulo, notes that while LNCSs are often promoted as healthier alternatives to sugar, the findings suggest certain sweeteners may negatively affect brain health over time.
The study included 12,772 Brazilian adults with a mean age of 52 who completed food-frequency questionnaires at baseline and underwent cognitive testing at the beginning, midpoint and end of follow-up. Researchers categorized participants into tertiles based on combined daily consumption of the seven LNCSs. The lowest tertile averaged about 20 mg/day and the highest tertile about 191 mg/day; for aspartame, that amount is roughly equivalent to one can of diet soda. Sorbitol was the most commonly consumed sweetener by weight, averaging 64 mg/day.
Cognitive assessment covered multiple domains—verbal fluency, working memory, word recall and processing speed—producing composite z-scores to track changes over time. After adjusting for age, sex, blood pressure, cardiovascular disease and other confounders, higher overall LNCS intake remained associated with a faster decline in global cognition, particularly in memory and verbal fluency.
Age and diabetes differences
When results were stratified by age, the associations were strongest among adults under 60: those in the highest consumption group showed greater declines in verbal fluency and global cognition compared with the lowest group. No significant associations were found in participants aged 60 and older. The link between LNCS consumption and cognitive decline was also stronger among participants with diabetes, suggesting that heavy use of sweeteners in this population could carry additional risk for cognitive aging.
Individual sweeteners
The study examined seven LNCSs: aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol and tagatose. Consumption of aspartame, saccharin, acesulfame-K, erythritol, sorbitol and xylitol was associated with faster declines in overall cognition and memory domains. Tagatose showed no measurable relationship with cognitive decline in this cohort.
Limitations and next steps
This observational study cannot prove cause and effect. Limitations include reliance on self-reported dietary data, potential selection bias from participant attrition, and residual confounding by unmeasured lifestyle or health behaviors. Not all available sweeteners were examined, and intake estimates are subject to recall error.
The authors call for further research to confirm these findings, explore biological mechanisms, and evaluate whether other refined sugar alternatives (for example, fruit-based or natural sweeteners) might present safer options for long-term brain health.
Funding: The research was supported by the Brazilian Ministry of Health, the Ministry of Science, Technology, and Innovation, and the National Council for Scientific and Technological Development.
About this cognitive decline and diet research news
Author: Renee Tessman
Source: AAN
Contact: Renee Tessman – AAN
Image: The image is credited to Neuroscience News
Original Research: Closed access. “Association Between Consumption of Low- and No-Calorie Artificial Sweeteners and Cognitive Decline: An 8-Year Prospective Study” by Claudia Kimie Suemoto et al., Neurology
Abstract
Association Between Consumption of Low- and No-Calorie Artificial Sweeteners and Cognitive Decline: An 8-Year Prospective Study
Background and Objectives
Consumption of low- and no-calorie sweeteners (LNCSs) has been tied to several adverse health outcomes, but their relationship with cognition is not well understood. This study aimed to investigate whether LNCS consumption is associated with cognitive decline over time.
Methods
A longitudinal observational analysis used data from the Brazilian Longitudinal Study of Adult Health, enrolling civil servants aged 35 and older and evaluated across three waves (2008–10, 2012–14, and 2017–19). Participants with incomplete dietary data, extreme caloric intake, or missing cognitive or covariate information at baseline were excluded. Diet was assessed with a food-frequency questionnaire to estimate combined and individual intake of seven LNCSs. Cognitive performance was measured across six tests, and linear mixed-effects models estimated associations between LNCS consumption and cognitive decline.
Results
Among 12,772 participants (mean age 51.9 years, 54.8% women, 43.2% Black/mixed race), mean LNCS consumption was 92.1 mg/day. In participants younger than 60, those in the highest tertile of combined LNCS intake experienced faster declines in verbal fluency and global cognition compared with the lowest tertile. No association was observed in participants aged 60 and older. Intake of aspartame, saccharin, acesulfame-K, erythritol, sorbitol and xylitol correlated with faster declines in global cognition, particularly in memory and verbal fluency domains. Patterns differed slightly by diabetes status: higher LNCS intake was linked to faster verbal fluency and global cognitive decline in people without diabetes, and to faster memory and global cognitive decline in people with diabetes.
Discussion
Over eight years, higher consumption of certain LNCSs was associated with an accelerated rate of cognitive decline. These findings raise concerns about potential long-term harms from artificial LNCSs and sugar alcohols on cognitive function. Study limitations include self-reported dietary measures, attrition-related selection bias, and possible residual confounding from other health behaviors. Continued research is needed to replicate these results and to explore safer alternatives for reducing sugar intake.