Study links artificial sweeteners to faster cognitive decline—except one

A large study involving 13,000 participants has uncovered a possible link between artificial sweeteners and faster cognitive decline. Published in Neurology on 3 September 2025, the research suggests that cutting down on sugar overall may be the best way to protect brain health over time. The study analysed seven sweeteners: aspartame, saccharin, acesulfam-K, erythritol, xylitol, sorbitol, and tagatose. Six of these—apart from tagatose—were connected to a quicker decline in memory and thinking skills. Those who consumed the highest amounts faced a 62% faster decline compared to those who used them the least. For the top consumers, the effect was similar to ageing an extra 1.6 years.

The impact was even more pronounced in participants with diabetes. While most sweeteners showed negative effects, tagatose stood out as an exception. This less common sweetener did not appear to harm cognitive function and may even offer health benefits.

Funding for the research came from the Brazilian Ministry of Health, the Ministry of Science, Technology and Innovation, and the National Council for Scientific and Technological Development. The findings highlight the risks of many artificial sweeteners while pointing to tagatose as a possible safer alternative. Researchers emphasised that reducing overall sugar intake remains the most effective strategy for preserving cognitive health as people age.