Key Takeaways
- People under 60 who consumed more artificial and low-calorie sweeteners had a faster decline in verbal fluency and overall thinking ability.
- For those over 60, no link between sweetener intake and cognitive decline was found.
- Specific sweeteners including aspartame, saccharin, acesulfame K, erythritol, sorbitol, and xylitol were linked to declines in memory and verbal skills.
- Both people with and without diabetes showed faster cognitive decline when consuming more sweeteners, though the affected areas differed.
- The study followed participants for 8 years and used repeated cognitive testing.
- Not all sweeteners were included in the study, and results were based on self-reported dietary intake, which may affect accuracy.
Artificial sweeteners are often used as a replacement for sugar, with the goal of reducing calories or managing blood sugar. But a large, long-term study published in Neurology examined whether these sweeteners are linked to changes in brain function over time.
The results suggest that higher intake of low- and no-calorie sweeteners was associated with a faster decline in memory and other cognitive skills though the effect was most notable in participants under 60.
What was studied
The study aimed to find out whether consuming low- and no-calorie sweeteners (LNCSs) is linked to cognitive decline over time.
Researchers looked at seven specific sweeteners:
- Aspartame
- Saccharin
- Acesulfame K
- Erythritol
- Xylitol
- Sorbitol
- Tagatose
Participants’ diets were assessed using a Food Frequency Questionnaire, and their cognitive performance was measured through six different tests.
How the study was conducted
This was a longitudinal observational study.
- Participants: 12,772 civil servants aged 35 and older at baseline.
- Timeframe: They were followed across three study waves between 2008 and 2019.
- Exclusions: Anyone with incomplete diet data, extreme reported calorie intake, or missing baseline cognitive data was excluded.
Researchers calculated average daily intake of the sweeteners and grouped participants into tertiles (low, medium, high). Cognitive performance was tracked by changes in test scores (z-scores) over time.
What this study found:
- Overall link: Higher consumption of sweeteners was associated with an accelerated decline in global cognition during 8 years of follow-up.
- Age differences:
- Under 60: Higher intake linked to faster decline in verbal fluency and overall cognition.
- 60 and older: No clear association found.
- By sweetener type: Aspartame, saccharin, acesulfame K, erythritol, sorbitol, and xylitol were each linked to faster decline in global cognition, especially in memory and verbal fluency.
- Diabetes status:
- Without diabetes: Higher intake linked to faster decline in verbal fluency and global cognition.
- With diabetes: Higher intake linked to faster decline in memory and global cognition.
What are the limitations of this study?
The authors highlighted several limitations:
- Dietary intake was self-reported, which can introduce errors.
- Some participants dropped out over time, raising the possibility of selection bias.
- Other lifestyle or health behaviors might have influenced the results (residual confounding).
Another limitation is that the study did not include every type of artificial sweetener currently in use. In addition, all dietary intake data were self-reported, which means some participants may not have recalled their consumption accurately.
In a press release, study author Dr. Suemoto emphasized that “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.”
Because this was an observational study, it cannot prove cause and effect.
Sources
Published in Neurology: Association Between Consumption of Low- and No-Calorie Artificial Sweeteners and Cognitive Decline: An 8-Year Prospective Study (September 3, 2025).
