For those who reach for diet cold drinks and artificially sweetened beverages as a thirst quencher or pick-me up, an updated study from the peer-reviewed journal Neurology presents some interesting data.
The newest findings from the research, led by the Universidade de São Paulo, suggest a concerning link between low- and no-calorie sweeteners (LNCS) used in diet drinks and accelerated cognitive decline, reports The Street.
In a pool of 12 772 Brazilian participants tested over eight years, people under 60 who drank LNCS regularly showed a faster decline in verbal fluency and global cognition. The studied LNCS included aspartame, saccharin, acesulfame k, erythritol, xylitol, sorbitol and tagatose.
Six of the seven sweeteners showed a link to cognitive decline, with tagatose being the one that did not.
Participants were tested at the beginning, middle, and end of the study to track changes, and then separated into three groups based on consumption levels.
The highest consumption level group showed a cognitive decline 62% faster than that of the lowest group. However, those over 60 did not show an association between LNCS and cognitive decline.
Previous concerns
This is, of course, far from the only negative news about artificial sweeteners, which have previously been associated with gastrointestinal symptoms, cardiovascular effects, and allergic reactions.
Many also think they cause cancer, although current research shows no conclusive evidence linking them to cancer risk. Some newer research, published in Frontiers in April 2026 suggests that use of artificial sweeteners could be passed on to offspring (but, like much of the other research, this study cannot yet confirm it).
The NutriNet Sant’ study, focused on nutrition and published in 2022, included more than 100 000 people and lasted nine years. Roughly 80% of the participants were women. At the end of the study, artificial sweeteners were linked to a 9% higher risk of any type of cardiovascular problem and an 18% greater risk of stroke.
Meanwhile, the diet soda market has continued to grow, with an estimated value of $55.8bn in 2025, according to Beverage Industry, with an average of 15% of Americans guzzling down diet soda daily.
But while yet another negative study may make people worry about dropping their Diet Coke habit, that might not be necessary just yet, according to study author Claudia Kimie Suemoto of the University of São Paulo. She said the findings don’t translate to a need to totally eliminate the occasional diet soda.
In an interview with Inc, she said the results of the study had, rather, raised bigger questions about what long-term, frequent consumption of artificial sweeteners may do to consumers.
“Based on our study alone, I would not tell someone to stop drinking diet cold drinks because of concerns about cognitive impairment,” she said, but noted that the study does lend more evidence to a link between artificial sweeteners and type 2 diabetes, as well as cardiovascular disease.
Study details
Association Between Consumption of Low- and No-Calorie Artificial Sweeteners and Cognitive Decline: An 8-Year Prospective Study
Natalia Gomes Goncalves, Euridice Martinez-Steele, Paulo A. Lotufo et al.
Published in Neurology on 30 July 2026
Abstract
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 three 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 six 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, consumption of combined LNCSs in the highest tertile was associated with a faster decline in verbal fluency (third tertile: β = −0.040, 95% CI −0.066 to −0.015) and global cognition (third tertile: β = −0.026, 95% CI −0.043 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 tertile 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 eight 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 behaviours.
Neurology article – Low- and No-Calorie Artificial Sweeteners and Cognitive Decline (Open access)
The Street article – study reveals alarming problem linked to drinking Diet Coke daily (Open access)
See more from MedicalBrief archives:
Artificial sweeteners’ link to higher risk of heart disease – French study
Study contradicts earlier findings on saccharin-for-sugar substitution and diabetes
Artificial sweeteners and increased cancer risk – French cohort study