A study published in Neurology, the medical journal of the American Academy of Neurology, has drawn renewed attention to the potential long-term effects of low- and no-calorie sweeteners after finding an association between higher consumption of several sweeteners and faster declines in certain measures of cognitive function and memory among adults, particularly those under the age of 60.
The sweeteners examined included aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol and tagatose. However, the findings do not establish that these substances directly cause memory loss or dementia. The research was observational and relied on dietary and health data collected over several years, meaning the results point to an association rather than proving a causal relationship.
Eight-Year Study Included More Than 12,000 Participants
Researchers analyzed data from 12,772 participants enrolled in a Brazilian longitudinal study. Their average age at baseline was approximately 51.9 years, while women accounted for 54.8% of the study population.
Participants were assessed across three study waves between 2008 and 2019. Researchers used dietary questionnaires to estimate consumption of seven low- and no-calorie sweeteners and conducted cognitive assessments covering six measures of cognitive function.
The primary objective was to examine whether consumption of these sweeteners was associated with changes in cognitive performance over time.
Sweeteners Examined in the Research
The study focused on seven low- and no-calorie sweeteners commonly used in foods and beverages:
- Aspartame
- Saccharin
- Acesulfame-K
- Erythritol
- Xylitol
- Sorbitol
- Tagatose
These substances differ in their chemical structures, nutritional properties and uses. The researchers therefore examined both combined consumption and, in some analyses, individual sweeteners.
Higher Consumption Associated With Faster Cognitive Decline
Among participants younger than 60, those in the highest consumption group for combined low- and no-calorie sweeteners experienced faster declines in verbal fluency and global cognition than those with lower consumption.
Several individual sweeteners were also associated with faster declines in global cognitive function, particularly in areas involving memory and verbal fluency.
The study also found differences according to diabetes status. Higher consumption was associated with faster declines in memory and global cognition among participants with diabetes, while associations among participants without diabetes involved verbal fluency and global cognition.
What About People Over 60?
One notable finding was the absence of a similar association between sweetener consumption and cognitive decline among participants aged 60 and older.
However, this does not mean that sweeteners are necessarily harmless after age 60, nor does the study establish that age eliminates any potential effect.
The difference could reflect statistical factors, variations in cognitive aging among older adults or other characteristics of the study population. The findings therefore should not be interpreted as evidence that sweeteners pose no cognitive concerns among older people.
Does the Study Prove That Sweeteners Cause Memory Loss?
No.
This distinction is essential when interpreting the findings.
The research was a longitudinal observational study. Researchers observed participants’ dietary patterns and cognitive changes over time rather than randomly assigning people to consume different amounts of sweeteners under controlled experimental conditions.
As a result, the study identifies an association but cannot establish that sweeteners themselves directly caused the observed cognitive decline.
The researchers also identified several limitations, including reliance on self-reported dietary information, potential selection bias resulting from participant attrition and the possibility of residual confounding from other health and lifestyle factors.
Why One Study Is Not Enough to Issue a Broad Recommendation
The findings raise important questions about long-term sweetener consumption, but they are not sufficient on their own to justify a blanket recommendation to stop using all sugar substitutes.
The more scientifically accurate interpretation is that the study adds new observational evidence to an area that requires further investigation, particularly to determine whether the observed association reflects a direct effect of sweeteners or is partly explained by other dietary, health or behavioral factors.
The study also examined seven specific sweeteners rather than every sugar substitute available on the market. Its findings therefore cannot automatically be generalized to every product marketed as a sugar alternative.
Why Are Low-Calorie Sweeteners Used?
Millions of people use sugar substitutes in foods and beverages, often to reduce sugar and calorie intake.
They are particularly popular among people seeking to limit added sugar or manage blood glucose levels. However, the nutritional and metabolic characteristics of individual sweeteners vary depending on their composition, quantity and role within the overall diet.
For that reason, assessing a person’s entire dietary pattern is generally more meaningful than focusing on a single ingredient in isolation.
More Research Is Needed
The study raises the possibility of long-term health concerns associated with low- and no-calorie sweeteners, while also highlighting the need for additional research.
This is particularly important because sweeteners represent a diverse group of substances with different chemical structures and biological properties. It would therefore be premature to assume that all sweeteners have identical effects on the brain or other parts of the body.
Further research, including studies with stronger designs for assessing causality and controlling for confounding factors, will be needed to clarify the relationship.
What Do the Findings Mean for Consumers?
For consumers, the study does not necessarily mean that everyone should immediately stop using artificial sweeteners. It does, however, reinforce the importance of moderation and caution against assuming that products containing sugar substitutes are automatically healthy regardless of how much is consumed.
Reducing overall reliance on highly sweetened foods and beverages may also be a more sustainable dietary approach than simply replacing large amounts of conventional sugar with alternative sweeteners.
People with diabetes or other conditions requiring specific dietary management should discuss significant dietary changes with their healthcare provider or a qualified nutrition professional.
A New Question for Brain-Health Research
The study comes amid growing scientific interest in the potential long-term health effects of low- and no-calorie sweeteners.
Neurology published the research in 2025 and subsequently issued a corrected version in November after identifying errors in some confidence intervals. The journal stated that the corrections did not alter the study’s overall conclusions.
The key message, therefore, is not that sweeteners have been proven to be a “silent danger” to the brain, but that the observed association warrants further investigation, particularly regarding high and long-term consumption.
As research continues, it remains too early to make definitive claims about all sugar substitutes. The study instead adds to the growing body of evidence examining how dietary patterns and specific food components may influence cognitive health over the long term.
