Ultra-processed foods linked to measurable drops in human attention span

New research from Monash University, the University of São Paulo and Deakin University shows a diet high in heavily processed foods can negatively impact the brain's ability to focus and increases the risk of developing dementia.

The study published today in Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring, a journal of the Alzheimer's Association, examined the diets and cognitive health of more than 2,100 Australian dementia-free adults middle-aged and older.

The findings demonstrate that a slight daily increase in a person's intake of ultra-processed foods (UPFs) is linked to a measurable drop in attention span – even if someone otherwise eats healthy.

Lead author Dr Barbara Cardoso, from the Department of Nutrition, Dietetics and Food and the Victorian Heart Institute at Monash University, said the study reinforces a clear connection between industrial food manufacturing and cognitive decline.

To put our findings in perspective, a 10 per cent increase in UPFs is roughly equivalent to adding a standard packet of chips to your daily diet.

For every 10 per cent increase in ultra-processed food a person consumed, we saw a distinct and measurable drop in a person's ability to focus. 

In clinical terms, this translated to consistently lower scores on standardised cognitive tests measuring visual attention and processing speed."

Dr. Barbara Cardoso, Department of Nutrition, Dietetics and Food and the Victorian Heart Institute at Monash University

The participants of the study consumed roughly 41 per cent of their daily energy from UPFs, closely mirroring the national Australian average of 42 per cent.

UPFs include everyday products like soft drinks, packaged salty snacks and ready-made meals – essentially anything that's not fresh whole foods.

Because the negative effects of UPFs take place regardless of a person's overall diet quality, even for people following a healthy Mediterranean diet, researchers say the degree of food processing plays a critical role in the damage.

"Food ultra-processing often destroys the natural structure of food and introduces potentially harmful substances like artificial additives or processing chemicals," Dr Cardoso said.

"These additives suggest the link between diet and cognitive function extends beyond just missing out on foods known as healthy, pointing to mechanisms linked to the degree of food processing itself."

Eating more UPFs was linked to an increase in dementia risk factors, which include health conditions such as high blood pressure or obesity that can actively be managed to protect the brain.

While the study did not find a direct association between UPFs and memory loss, attention span is the foundation for many important brain operations, such as learning and problem-solving.