Even small unhealthy snacks can affect the brain. The demonstrated link between ultra-processed foods and attention problems
A healthy diet does not completely negate the effect of ultra-processed foods, even if they are consumed in small amounts. A recently published study showed that an increase of just 10% of these products in the daily diet, the equivalent of a small bag of chips or a ready-made meal, is associated with a lower score on attention tests and a higher estimated risk of dementia among adults over 40.
The research, led by Barbara Cardoso, senior lecturer in nutrition and dietetics at Monash University in Melbourne, Australia, involved 2,192 dementia-free Australian adults aged 40 to 70 enrolled in the Healthy Brain Project, a long-term research program into brain health and dementia risk.
The authors compared the share of ultra-processed foods in the diet with the results obtained on cognitive tests and with the CAIDE score, used to estimate the risk of dementia in middle age.
The results were published in Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring at the end of April 2026.
“For every 10% increase in ultra-processed food consumption, we saw a distinct and measurable decrease in that person's ability to focus. In clinical terms, this translated into consistently lower scores on standardized cognitive tests that measure visual attention and processing speed,” said Barbara Cardoso.
What are ultra-processed foods?
To classify the foods, the researchers used the Nova system, developed at the University of Sao Paulo, Brazil, which divides products into four groups:
- unprocessed or minimally processed foods (vegetables, fruits, fresh meat, milk);
- processed culinary ingredients (oil, salt, butter);
- processed foods (bread, cheese, simple preserves);
- ultra-processed foods.
The last category includes industrial products obtained by breaking down food into molecules, then recombined with dyes, flavors, sweeteners, emulsifiers and other additives, such as chips, chocolate bars, breakfast cereals rich in sugar, carbonated drinks, industrial sausages, instant soups, frozen ready-made foods.
Participants' adherence to the Mediterranean diet was assessed using a standardized questionnaire, and cognitive tests were performed online via the Cogstate Brief Battery, which measures attention and memory.
This association was also preserved in people with a diet close to the Mediterranean model. For the authors, this result indicates that not only the general quality of the diet matters, but also the degree of industrial processing of the products consumed.
“We demonstrated that the association between ultra-processed foods and attention problems is independent of diet quality, which emphasizes that food processing itself is an important factor in the relationship between diet and cognitive health,” explained the study coordinator.
Industrial processing destroys the natural structure of food and introduces potentially harmful substances, from additives to compounds that form at high temperatures.
An early warning sign
It should be noted that the researchers did not observe any link between the consumption of ultra-processed foods and memory loss. The association appeared strictly in the case of attention and information processing speed. However, the authors believe this could be an early warning signal, given that attention underlies other more complex processes such as learning, problem solving and memory formation.
“Early attention disturbances may precede broader cognitive deficits. However, the evidence remains inconclusive, and further research is needed to clarify the dynamics over time of these associations,” the study authors noted.
The result confirms an already visible trend
In January 2026, a team at Harvard Medical School, led by neurologist W. Taylor Kimberly, reported a similar association: for every 10% increase in ultra-processed food consumption, the risk of cognitive impairment was 16% higher. The link was also present in people who frequently consumed vegetables and fruits.
“Together, these studies show that higher consumption of ultra-processed foods is consistently associated with poorer cognitive performance,” Taylor Kimberly told CNN.
The neurologist added that replacing ultra-processed foods with minimally processed foods over a period of five to six years could reduce the risk of cognitive decline by 12 percent.
Another 2022 study of nearly 10,000 adults found that people who ate the highest amounts of ultra-processed foods had a 28 percent faster rate of overall cognitive decline and a 25 percent decline in executive function (mental abilities to organize, concentrate, and make decisions).
A 2024 systematic meta-analysis of 45 studies and nearly 10 million people confirmed the association between high consumption of such products and dementia, along with dozens of other chronic diseases.
The role of the gut-brain axis
The mechanisms by which ultra-processed foods affect the brain are multiple. Barbara Cardoso stated that these products have been associated with negative changes in the endocrine system and gut microbiota, both of which affect the brain through the gut-brain axis.
In addition, it fuels a number of well-known cardiovascular risk factors for dementia, such as type 2 diabetes, high blood pressure, obesity and elevated LDL cholesterol.
It is also hypothesized that certain additives, emulsifiers, or compounds formed during heavy processing (such as advanced glycation end products or acrylamide in chips and products browned at high temperatures) may maintain systemic inflammation and oxidative stress, two processes involved in brain aging.
Also, ultra-processed foods are designed to be eaten quickly and in large quantities, resulting in reduced intake of fiber, polyphenols, omega 3 fatty acids and B vitamins, all of which have a documented role in neuroprotection.
The age at which diet starts to matter more to the brain
The coordinator of the Australian study draws attention to the fact that middle age, i.e. between 40 and 60 years, represents the period when dietary changes, for preventive purposes, can be extremely effective.
“Midlife is a stage that offers an important opportunity to address modifiable risk factors before neuropathological changes compatible with dementia set in,” Barbara Cardoso said.
The Australian team's recommendations include the step-by-step replacement of industrial products with unprocessed or minimally processed foods cooked at home.
This includes vegetables, fruits, legumes, fish, nuts, seeds and extra virgin olive oil, foods that are the basis of the Mediterranean diet, the MIND diet and the DASH diet.
In studies so far, these eating patterns have been associated with a lower risk of cardiovascular disease, diabetes and dementia.
The Australian study also has limitations acknowledged by the authors. This is cross-sectional, so it shows an association, not a clear cause and effect relationship.
Dietary data comes from questionnaires completed by participants, with the usual pitfalls of this type of research.
The sample consisted largely of women, 75.4% of participants, most of whom had an education level and socio-economic status above the average of the Australian population, so the results cannot be automatically extended to all categories of people.
