Popular Artificial Sweeteners Linked to Faster Memory Decline in Large Study

Several widely used sugar substitutes may be quietly accelerating the aging of the brain, according to a large new study that followed nearly 13,000 adults over time. The research, published in Neurology, the medical journal of the American Academy of Neurology, found that people who consumed the most artificial sweeteners showed measurably faster declines in memory and thinking skills than those who consumed the least.

The scientists tracked seven sweeteners that contain little or no calories and are found in diet sodas, low-sugar snacks and countless "sugar-free" products. When they compared the heaviest consumers with the lightest, the gap was stark: the highest intake was associated with cognitive aging roughly 1.6 years faster than the lowest. In other words, the brains of frequent sweetener users appeared to slip in performance as though they were more than a year and a half older.

The effect was not uniform across the population. It was most pronounced in adults under the age of 60 and in people with diabetes — two groups that, ironically, are often steered toward artificial sweeteners precisely to avoid the health risks of sugar. That pattern raises pointed questions about products marketed as the healthier alternative, and about how much of the population unknowingly consumes them in large amounts.

Researchers were careful to stress the limits of the findings. The study is observational, meaning it can identify an association between sweetener consumption and faster cognitive decline but cannot prove that the sweeteners are the cause. Other factors common among heavy consumers of diet products — underlying metabolic conditions, overall diet quality or lifestyle — could contribute to the results. The authors said more research, including controlled experiments, is needed before anyone concludes that sweeteners directly harm the brain.

Still, the scale of the study and the size of the effect are likely to intensify scrutiny of ingredients that have long been treated as benign. Artificial sweeteners are consumed by hundreds of millions of people worldwide, and prior research has already hinted at links to metabolic and cardiovascular problems. The new work adds cognition to that list of concerns, suggesting that the everyday choice between sugar and its substitutes may carry consequences that reach all the way to the aging brain.

Experts not involved in the research urged consumers not to panic but to pay attention. They noted that the healthiest option remains reducing overall reliance on intensely sweet foods and drinks, whether sweetened with sugar or its substitutes, rather than simply swapping one for the other. For regulators and food companies, the findings are a prompt to fund the kind of long-term controlled trials that could finally settle whether the sweeteners in so many "diet" products are truly as harmless as their labels imply.