Guzzling just one diet fizzy drink everyday could rapidly raise the risk of brain decline, concerning research has suggested. 

Commonly-used sweeteners including aspartame, found in drinks like Diet Coke, Sprite and products like Extra chewing gum as sugar alternatives, have long been linked to certain cancers and heart issues.

But now, Brazilian experts have found that consuming high levels of the additives could also steal years from the brain. 

Higher consumption of 'added sugars', meaning those above the natural content of a food or drink item—just one can of diet drink each day—was linked to a 62 per cent higher risk of brain ageing.

This was equivalent to roughly 1.6 years of ageing. 

The risk was particularly heightened in those with diabetes, who are more likely to use artificial sweeteners as sugar substitutes, the researchers also found. 

Experts, who labelled the findings important, said consumption of low and no-calorie sweeteners could pose 'long-term harm' on brain function but cautioned that further research was vital to prove the link. 

Dr Claudia Kimie Suemoto, an assistant professor in cardiovascular disease and dementia at the University of São Paulo and study co-author, said: '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. 

'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. 

'More research is needed to confirm our findings and to investigate if other refined sugar alternatives, such as apple sauce, honey, maple syrup or coconut sugar, may be effective alternatives.' 

Brain ageing can affect cognitive functions such as memory, attention, and multitasking, increasing susceptibility to neurodegenerative diseases such as dementia. 

In the study, researchers tracked the dietary habits of 12,772 adults aged 52 on average.

They were then divided into three groups based on the total amount of artificial sweeteners they consumed.

The artificial sweeteners examined included aspartame, saccharin, acesulfame-K, erythritol, xylitol, sorbitol and tagatose. 

These are mainly found in ultra-processed foods like flavored water, soda, energy drinks, yogurt and low-calorie desserts. Some are also used as a standalone sweetener. 

The lowest group consumed an average of 20mg per day of such sweeteners, while the highest logged 191 mg per day on average.  

For aspartame, this amount is equivalent to one can of a diet fizzy drink. Sorbitol had the highest consumption, with an average of 64 mg/day.

Over a follow-up of eight years, participants undertook cognitive tests at the start, the middle and again at the end of the study. These assessed working memory, word recall and processing speed.

After accounting for factors that could skew the results, such as age and other diagnosed health conditions, the researchers found people who consumed the highest amount of sweeteners experienced brain ageing that was 62 per cent higher than the lowest group. 

This was equivalent to around 1.6 years of ageing, they said.

Those in the middle group saw a decline that was 35 per cent faster than the lowest group, equivalent to about 1.3 years of aging.

When researchers broke the results down by age, they also found that volunteers under the age of 60 who consumed the highest amounts of sweeteners showed faster declines in verbal fluency and overall cognition when compared to those who consumed the lowest amounts. 

But they did not find a link in people over the age of 60. 

Writing in the journal Neurology, the scientists said: 'Our findings suggest the possibility of long-term harm from low and no-calorie sweetener consumption, particularly artificial low and no-calorie sweeteners and sugar alcohols, on cognitive function.'

They did, however, acknowledge that the study had some limitations including the fact diet information was self reported and participants 'may not have remembered accurately everything they ate'. 

It comes as a major safety review by World Health Organization bosses in 2023 ruled that aspartame would be classed as 'possibly carcinogenic to humans'.

This is because aspartame only poses a definite risk to those who consume massive amounts, the UN agency concluded. 

Type 2 diabetes occurs when the body doesn't make enough insulin or the insulin it makes doesn't work properly. 

This hormone is needed to bring down blood sugar levels.

Having high blood sugar levels over time can cause heart attacks and strokes, as well as problems with the eyes, kidneys and feet. 

Symptoms of the condition, which is diagnosed with a blood test, include excessive thirst, tiredness and needing to urinate more often. But many people have no signs.

Almost 4.3million people were living with diabetes in 2021/22, according to the latest figures for the UK.