Researchers in Brazil tracked 12,772 adults, with an average age of 52, over a period of eight years.
The study examined seven widely used artificial sweeteners: aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol and tagatose.
Those who consumed the highest amounts — averaging 191 milligrams per day — showed a 62% faster decline in overall cognition compared to participants consuming the lowest amounts, equivalent to about 1.6 years of additional aging.
People in the middle group, averaging 64 milligrams per day, showed a 35% faster decline, equal to 1.3 years of aging.
“The results suggest that some sweeteners, often marketed as healthy alternatives to sugar, may in fact harm brain health over time,” said study author Claudia Kimie Suemoto, MD, Ph.D., of the University of São Paulo.
The link appeared stronger among people with diabetes and was most evident in participants under 60, particularly affecting verbal fluency and memory.
Among the tested sweeteners, aspartame, saccharin, acesulfame-K, erythritol, xylitol and sorbitol were associated with faster decline, while tagatose showed no significant link.
Participants were given cognitive tests throughout the study, measuring areas such as memory recall, language ability, working memory and processing speed.
Researchers adjusted results for age, sex, blood pressure and cardiovascular disease, but stressed the findings show correlation, not causation.
Suemoto noted the need for further research, including studies on whether natural alternatives like honey or coconut sugar may be safer options.
One limitation of the study was reliance on self-reported dietary data, which may not have been fully accurate.