Many of us reach for sugar substitutes, believing they offer a guilt-free sweet fix. We swap sugar for artificial sweeteners in our coffee, baked goods, and even everyday drinks, hoping to cut calories without sacrificing taste. However, emerging research suggests these seemingly innocent alternatives might come with an unexpected side effect: a potential link to accelerated cognitive decline. This news might change how you view your “healthy” choices.

The Research Unpacked

A study published in the scientific journal Neurology in fall 2025 followed over 12,000 Brazilian adults for approximately eight years. Researchers meticulously tracked participants’ intake of seven common sugar substitutes, including aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol, and tagatose. They then assessed cognitive function at the study’s beginning, middle, and end. The findings were compelling and warrant our attention.

Participants were categorized by their average daily sugar substitute intake: low (20 mg), medium (66 mg), and high (191 mg). After adjusting for various confounding factors like age, sex, and health conditions, the results were striking. The group with the highest intake of sugar substitutes experienced a 62% faster decline in overall cognitive function compared to the lowest-intake group. This difference is roughly equivalent to 1.6 years of accelerated aging. Even the medium-intake group saw a 35% faster decline, comparable to 1.3 years of aging.

These cognitive declines weren’t just general; they affected specific areas. The highest-intake category showed a 32% drop in memory function. Verbal fluency, our ability to retrieve words easily, also suffered significantly, with declines of 110% for the middle-intake category and a staggering 173% for the highest-intake group. This trend was particularly pronounced in participants under 60 and those with diabetes.

Navigating Your Sweet Choices

Christine Byrne, MPH, RD, a dietitian and owner of Ruby Oak Nutrition, reminds us that “nutrition is complicated, and many food choices come with pros and cons.” While sugar substitutes can aid in blood sugar control and reduce overall added sugar intake, this research highlights a potential downside we haven’t fully understood. It’s a reminder that what seems like a simple swap can have complex implications for our health.

So, what does this mean for you? It doesn’t mean you must eliminate all sugar substitutes immediately. Instead, it encourages a more mindful approach. Consider reducing your reliance on artificially sweetened products. Opt for naturally sweet alternatives like fruit or a small amount of real sugar. Pay attention to food labels and be aware of the sugar substitutes present in your diet. This study serves as an important piece of the puzzle, urging us to question whether the benefits truly outweigh the potential long-term risks to our cognitive health.