Artificial sweeteners have become staples in modern diets. They are widely promoted as healthier alternatives to sugar and embraced by those wishing to cut calories or manage blood sugar. But a growing body of research has been uncovering their negative impacts on health. A specific study from Brazil also suggests that routine consumption of these substitutes may accelerate cognitive decline and make the brain age faster.
Artificial Sweeteners and the Brain: A Study Raises New Concerns
Background
The study was published on 3 September 2025 in Neurology, the medical journal of the American Academy of Neurology, and tracked nearly 13000 Brazilian adults for 8 years. Participants were evaluated on memory, language, and reasoning abilities. Their dietary patterns were analyzed to measure exposure to seven different artificial sugar alternatives.
Researchers spearheaded by Dr. Claudia Kimie Suemoto examined the independent role of artificial sweeteners or sugar substitutes after earlier work connected ultra-processed food intake with faster brain decline. Many ultra-processed foods contain sweeteners. The research team aimed to isolate their potential effects on cognitive performance.
Dietary information was collected at baseline through food frequency questionnaires. Participants reported consumption of processed foods and beverages containing at least aspartame, saccharin, acesulfame potassium, erythritol, xylitol, sorbitol, or tagatose. Their cognitive abilities were measured repeatedly, and statistical models accounted for risk factors.
Key Findings
The researchers discovered remarkable differences between individuals consuming very small amounts of sweeteners and those consuming much more. The higher intake group averaged 191 milligrams per day, roughly equal to a single can of diet soda, while the lowest group averaged only about 20 milligrams daily. Below are the key findings:
• Accelerated Cognitive Decline: Adults with the highest daily intake experienced a 62 percent faster decline in memory, language, and thinking skills compared with those consuming the least. This change represented the equivalent of approximately 1.6 years of accelerated brain aging within the follow-up period.
• Impact of Diabetes Mellitus: The link was stronger among diabetic people. Sweetener consumption appeared to compound existing vulnerabilities connected to metabolic and vascular problems. This suggests that diabetic individuals may be especially sensitive to the cognitive consequences of regular intake of sugar alternatives.
• Critical Midlife Exposure: Effects were strongest in participants under 60 years old. This is contrary to expectations. The study did not find a significant effect in individuals over 60. Researchers suggested that midlife may represent a sensitive window when exposures can shape long-term brain health and disease risk.
• Not All Are Sweeteners Equal: 6 out of 7 substances were linked with decline. Tagatose was the only sweetener not associated with reduced cognitive performance, making it an exception. The others, including aspartame and saccharin, were consistently associated with faster deterioration across multiple domains of cognition.
Implications
The study design has limitations that must be taken into consideration. Specifically, because the methodology is generally observational, the findings do not prove that sweeteners cause brain decline, only that they are associated. Food frequency questionnaires are self-reported and may not perfectly reflect actual intake. Diet changes over time were not tracked.
However, despite the above, the study adds to a growing body of evidence connecting artificial sweeteners with health concerns ranging from metabolic disorders to potential cancer risk. Researchers emphasize that more controlled studies are needed to confirm causality and to better understand the specific biological mechanisms at work.
Moderation appears to be the safest advice for now. The researchers suggest that frequent use of artificial sweeteners or sugar substitutes could accelerate brain aging in midlife, particularly among those with diabetes. Specific sugar alternatives such as tagatose or natural sweetener options like honey and maple syrup may be considered safer and healthier choices.
FURTHER READING AND REFERENCE
- Gonçalves, N. G., Martinez-Steele, E., Lotufo, P. A., Bensenor, I., Goulart, A. C., Barreto, S. M., Giatti, L., de Faria, C. P., Molina, M. del C. B., Caramelli, P., Marchioni, D. M., & Suemoto, C. K. 2025. “Association Between Consumption of Low- and No-Calorie Artificial Sweeteners and Cognitive Decline.” Neurology. 105(7). DOI: 1212/wnl.0000000000214023