Artificial Sweeteners May Speed Up Cognitive Decline

Artificial sweeteners are everywhere, yet their effects on the brain are largely unknown.

New research in Neurology, the medical journal of the American Academy of Neurology, found that frequent consumption of several artificial sweeteners may accelerate cognitive decline, especially in middle-aged adults and those with diabetes.

Artificial sweeteners may influence brain aging

Global dementia cases are set to nearly triple from ~57 million in 2019 to ~153 million by 2050. Although aging populations and rising chronic diseases are major drivers behind this increase, it isn’t the whole story. Many forms of dementia are not inevitable and lifestyle choices, from diet and exercise to managing blood sugar, play a big part in how the brain ages.

Ultra-processed foods – such as sodas, desserts, flavoured yogurts, etc., – have been linked to faster cognitive decline and higher dementia risk. These products often contain artificial sweeteners, which have been marketed as safe alternatives to sugar, and are widely used by people trying to cut calories or manage diabetes.

However, the science on sweeteners and brain health is unclear, and “little is known about the association between consumption of low- and no-calorie sweeteners and cognition,” explained the authors of the latest paper.

A few studies have tied saccharin or sucralose to higher dementia risk or poorer memory, while others reported no effect at all. Until now, no long-term, large-scale study has tested the impact of several different sweeteners on cognitive decline.

The latest research followed more than 12,000 adults in Brazil for nearly a decade, tracking their use of 7 common sugar substitutes, from aspartame to tagatose, measuring changes in thinking and memory.

Artificial sweeteners linked to faster memory loss

The study used data from the Brazilian Longitudinal Study of Adult Health, which included 12,772 civil servants with an average age of 52 years. People with dementia, Parkinson’s or incomplete records were excluded.

At the start of the study, participants filled out detailed food frequency questionnaires covering the previous year. From this, the team estimated intake of seven sweeteners: aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol and tagatose. Based on consumption, participants were sorted into three groups, from lowest to highest intake.

Cognitive testing was conducted at baseline and repeated at follow-ups, which covered memory, verbal fluency, processing speed and a combined measure of global cognition.

The participants in the middle consumption group had a 35% faster decline in global cognition compared to the lowest group, equivalent to ~1.3 extra years of aging. Those in the highest group had a 62% faster decline, or ~1.6 years of added aging.

However, the link was seen only in people under 60 years old, with no association found in those older than 60 years. Diabetes also amplified the effect; among participants with diabetes, higher intake was linked to stronger declines, particularly in memory.

Looking at individual sweeteners, aspartame, saccharin, acesulfame-K, erythritol, xylitol and sorbitol were all tied to faster decline. Tagatose stood out as the only one without harmful associations.

Daily users also showed faster decline compared to occasional users, underscoring that even moderate long-term intake may matter for brain health.

Implications for middle-aged adults and diabetes management

The study points to a sobering possibility: some sugar substitutes may speed up cognitive aging, especially in middle-aged adults. Common sweeteners such as aspartame and saccharin showed the strongest links – a concerning finding for those with diabetes.

“Low- and no-calorie sweeteners are often seen as a healthy alternative to sugar; however, our findings suggest certain sweeteners may have negative effects on brain health over time,” said corresponding author Dr. Claudia Kimie Suemoto, an associate professor of geriatrics at the University of São Paulo.

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She added: “While we found links to cognitive decline for middle-aged people both with and without diabetes, people with diabetes are more likely to use artificial sweeteners as sugar substitutes.”

Although the results don’t prove that sweeteners cause decline, they may raise concerns to warrant caution. The data suggest that not all substitutes are equal, and natural options such as tagatose, or sweeteners from fruit or honey, may be safer choices for long-term brain health.

“More research is needed to confirm our findings and to investigate if other refined sugar alternatives, such as applesauce, honey, maple syrup or coconut sugar, may be effective alternatives,” said Suemoto.

However, diet was self-reported, which leaves room for error. Additionally, only the baseline diet was recorded, meaning changes over time were missed. There was also no brain imaging to test mechanisms, and some widely used sweeteners, such as sucralose and stevia, weren’t studied.

Future work will need to replicate these results in other groups, test biological pathways and run controlled trials.

Reference: Gonçalves NG, Martinez-Steele E, Lotufo PA, et al. Association between consumption of low- and no-calorie artificial sweeteners and cognitive decline. Neurology. 2025. doi: 10.1212/WNL.0000000000214023

This article is a rework of a press release issued by the American Academy of Neurology. Material has been edited for length and content.