Summary: A large study of nearly 13,000 adults found that consuming high levels of certain artificial sweeteners is linked to faster declines in memory and thinking over eight years. The effect was particularly strong in people with diabetes and those under 60.
Some sweeteners, like aspartame and saccharin, were strongly associated with decline, while tagatose was not. While the study does not prove causation, it raises concerns about long-term brain health risks from common sugar substitutes.
Key Facts
- Faster Decline: High sweetener consumers showed a 62% faster drop in cognition, equal to 1.6 years of aging.
- Diabetes Link: Effects were more pronounced in people with diabetes, who often use sweeteners as sugar alternatives.
- Not All Equal: Tagatose showed no link, unlike other sweeteners tested.
Source: AAN
Some sugar substitutes may come with unexpected consequences for long-term brain health, according to a study published in the September 3, 2025, issue of Neurology.
The study examined seven low- and no-calorie sweeteners and found that people who consumed the highest amounts experienced faster declines in thinking and memory skills compared to those who consumed the lowest amounts.
The link was even stronger in people with diabetes. While the study showed a link between the use of some artificial sweeteners and cognitive decline, it did not prove that they were a cause.
The artificial sweeteners examined in the study were aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol and tagatose. These are mainly found in ultra-processed foods like flavored water, soda, energy drinks, yogurt and low-calorie desserts. Some are also used as a standalone sweetener.
“Low- and no-calorie sweeteners are often seen as a healthy alternative to sugar, however our findings suggest certain sweeteners may have negative effects on brain health over time,” said study author Claudia Kimie Suemoto, MD, PhD, of the University of São Paulo in Brazil.
The study included 12,772 adults from across Brazil. The average age was 52, and participants were followed for an average of eight years.
Participants completed questionnaires about diet at the start of the study, detailing what they ate and drank over the past year. Researchers divided them into three groups based on the total amount of artificial sweeteners they consumed.
The lowest group consumed an average of 20 milligrams per day (mg/day) and the highest group consumed an average of 191 mg/day. For aspartame, this amount is equivalent to one can of diet soda. Sorbitol had the highest consumption, with an average of 64 mg/day.
Participants were given cognitive tests at the start, middle and end of the study to track memory, language and thinking skills over time. The tests assessed areas such as verbal fluency, working memory, word recall and processing speed.
After adjusting for factors such as age, sex, high blood pressure and cardiovascular disease, researchers found people who consumed the highest amount of sweeteners showed faster declines in overall thinking and memory skills than those who consumed the lowest amount, with a decline that was 62% faster.
This is the equivalent of about 1.6 years of aging. Those in the middle group had a decline that was 35% faster than the lowest group, equivalent to about 1.3 years of aging.
When researchers broke the results down by age, they found that people under the age of 60 who consumed the highest amounts of sweeteners showed faster declines in verbal fluency and overall cognition when compared to those who consumed the lowest amounts. They did not find links in people over 60. They also found that the link to faster cognitive decline was stronger in participants with diabetes than in those without diabetes.
When looking at individual sweeteners, consuming aspartame, saccharin, acesulfame-k, erythritol, sorbitol and xylitol was associated with a faster decline in overall cognition, particularly in memory.
They found no link between the consumption of tagatose and cognitive decline.
“While we found links to cognitive decline for middle-aged people both with and without diabetes, people with diabetes are more likely to use artificial sweeteners as sugar substitutes,” Suemoto said.
“More research is needed to confirm our findings and to investigate if other refined sugar alternatives, such as applesauce, honey, maple syrup or coconut sugar, may be effective alternatives.”
A limitation of the study was that not all artificial sweeteners were included. Also, diet information was reported by the participants, who may not have remembered accurately everything they ate.
Funding: The study 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 associated with adverse health outcomes. However, little is known about the association between consumption of LNCSs and cognition. The aim of this study was to investigate the association between consumption of LNCSs and cognitive decline.
Methods
We conducted a longitudinal observational study using data from civil servants aged 35+ years at baseline who were enrolled in the Brazilian Longitudinal Study of Adult Health and evaluated across 3 study waves (2008–10, 2012–14, and 2017–19).
Participants with incomplete dietary data, extreme caloric intake (<1st percentile or >99th percentile), and incomplete data for cognitive tests and covariates at baseline were excluded.
A Food Frequency Questionnaire was used to calculate combined and individual consumption of 7 LNCSs (aspartame, saccharin, acesulfame k, erythritol, xylitol, sorbitol, and tagatose). We estimated z-scores across 6 cognitive tests. The association of LNCSs with cognitive decline was evaluated using linear mixed-effects models.
Results
Among 12,772 participants (mean age 51.9 ± 9.0 years, 54.8% women, 43.2% Black/mixed race), the mean consumption of LNCSs was 92.1 ± 90.1 mg/d.
Among participants aged younger than 60 years, consumption of combined LNCSs in the highest tertiles was associated with a faster decline in verbal fluency (second tertile: β = −0.016, 95% CI −0.040 to −0.008; third tertile: β = −0.040, 95% CI −0.064 to −0.016) and global cognition (second tertile: β = −0.008, 95% CI −0.024 to 0.008; third tertile: β = −0.024, 95% CI −0.040 to −0.008).
There was no association between tertiles of LNCSs and cognitive decline in participants aged 60+ years. Consumption of aspartame, saccharin, acesulfame k, erythritol, sorbitol, and xylitol was associated with a faster decline in global cognition, particularly in memory and verbal fluency domains.
Consumption of combined LNCSs in the highest tertiles was associated with a faster decline in verbal fluency and global cognition in participants without diabetes and faster decline in memory and global cognition in participants with diabetes.
Discussion
Consumption of LNCSs was associated with an accelerated rate of cognitive decline during 8 years of follow-up.
Our findings suggest the possibility of long-term harm from LNCS consumption, particularly artificial LNCSs and sugar alcohols, on cognitive function. Study limitations include self-reported dietary data, selection bias from attrition, and residual confounding from co-occurring health behaviors.
