Most Americans know that ultra-processed foods are bad for cardiovascular health, weight, and blood sugar. The emerging scientific picture suggests the brain may be an earlier and more sensitive victim — and new research confirms the damage extends to cognitive function even when the rest of a person's diet is otherwise healthy.
A study published in Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring, a journal of the Alzheimer's Association, found that each 10% increase in ultra-processed food (UPF) consumption was associated with measurable declines in attention and mental processing speed in middle-aged and older adults — and that this association held regardless of how healthy the rest of the diet was. The study received renewed coverage in ScienceDaily on June 8, 2026.
That last finding is the critical one: the harm from ultra-processed foods appears to be driven by the industrial processing itself, not simply by the displacement of nutritious foods. You cannot eat a bag of chips and compensate fully by also eating a salad.
What the Study Measured — and What It Found
Researchers from Monash University, the University of São Paulo, and Deakin University analyzed data from 2,192 Australian adults aged 40 to 70 — all dementia-free at enrollment — drawn from the Healthy Brain Project, funded in part by the National Health and Medical Research Council and the Alzheimer's Association. Participants completed a validated food frequency questionnaire and four standardized cognitive function tests (the Cogstate Brief Battery), assessing attention, memory, and processing speed. They also provided information on physical activity, demographics, and other health factors, allowing calculation of dementia risk using the validated CAIDE tool.
Diet was classified using the Nova system, which categorizes foods into four groups based on the extent and purpose of industrial processing, with Group 4 — ultra-processed foods (UPFs) — defined as products created through intense industrial manufacturing, typically made from refined ingredients and containing cosmetic additives including artificial colors, flavors, and preservatives.
The key findings:
- Each 10% increase in UPF intake was associated with lower attention scores (−0.05 points) on standardized cognitive tests measuring visual attention and processing speed
- Each 10% increase in UPF intake was also associated with higher dementia risk scores (+0.24 points) on the CAIDE tool
- Both associations were independent of Mediterranean diet adherence — meaning the damage from UPFs was not explained by the displacement of healthy foods but appeared to be a direct effect of the processed food itself
- The study did not find a significant association between UPF intake and memory loss — attention and processing speed, not memory, were the affected domains
| UPF Study Key Data | Detail |
| Published in | Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring |
| ScienceDaily coverage | June 8, 2026 |
| Study type | Cross-sectional analysis |
| Lead author | Dr. Barbara Cardoso, Monash University |
| Institutions | Monash University, University of São Paulo, Deakin University |
| Participants | 2,192 Australian adults, ages 40–70, dementia-free |
| Data source | Healthy Brain Project |
| Effect per 10% UPF increase (attention) | −0.05 points on standardized cognitive tests |
| Effect per 10% UPF increase (dementia risk) | +0.24 points on CAIDE tool |
| Independent of Mediterranean diet | Yes — processing itself is implicated, not food displacement |
| Cognitive domains affected | Visual attention and mental processing speed |
| Cognitive domain not significantly affected | Memory |
| Average UPF share of participant diet | ~41% (Australian average: 42%) |
| U.S. UPF share of caloric intake | >50% |
Why Attention — Not Memory — Is the Finding to Watch
The study's authors and independent experts note that the absence of a significant memory association is not a reassuring finding. Quite the opposite.
"Because attention serves as the foundation for so many aspects of thinking, declines in focus may represent an important early warning sign of broader cognitive changes," ScienceDaily reported in its June 8, 2026 coverage of the paper.
Attention is the cognitive gatekeeper. Sustained focus is necessary for learning, problem-solving, occupational performance, and safe driving. Executive function — including working memory, planning, and impulse control — depends on attentional resources. Research on cognitive aging consistently shows that attention deficits often precede more obvious memory changes by years, making them a meaningful early indicator of neurological risk.
Lead author Dr. Barbara Cardoso, from the Department of Nutrition, Dietetics and Food and the Victorian Heart Institute at Monash University, offered a concrete framing: "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 standardized cognitive tests measuring visual attention and processing speed."
To put the 10% threshold in context: Dr. Cardoso stated that "a 10 per cent increase in UPFs is roughly equivalent to adding a standard packet of chips to your daily diet."
Dr. W. Taylor Kimberly, a professor of neurology at Harvard Medical School, called the research "an important addition to the growing evidence base showing the potential harms of ultraprocessed foods on the brain," according to CNN.
What Ultra-Processed Foods Are — and How to Recognize Them
Ultra-processed foods are not simply "unhealthy" foods. They are defined by the nature of their industrial manufacturing, not just their nutritional content. Common UPFs include packaged snack foods (chips, crackers, pretzels), sweetened beverages (soda, energy drinks, flavored milks), processed meats (hot dogs, packaged deli meats, nuggets), packaged baked goods, breakfast cereals with added sugar, instant noodles and soups, flavored yogurts, and most fast food items.
In the United States, ultra-processed foods account for more than 50% of daily caloric intake on average — higher than the 41% to 42% reported in the Australian study population. This means American adults may be experiencing the cognitive effects documented in this research at even higher rates than the study detected.
The finding that Mediterranean diet adherence did not protect against UPF-associated cognitive decline suggests that the standard dietary advice — "eat more vegetables, fruits, and whole grains" — is necessary but not sufficient. The specific reduction of ultra-processed foods, not simply the addition of healthy foods, appears to be independently important for brain health.
Frequently Asked Questions
What did the ultra-processed food and brain study find?
Published in Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring (Alzheimer's Association journal), the study of 2,192 adults aged 40–70 found that each 10% increase in ultra-processed food intake was associated with measurably lower scores on attention and processing speed tests, and higher calculated dementia risk — independently of how healthy the rest of the diet was.
Does eating healthy otherwise protect your brain from ultra-processed food?
Partially — but not fully. The study found that the association between UPF intake and reduced attention was independent of Mediterranean diet adherence. This suggests the industrial processing itself, not just the replacement of healthy foods, drives the cognitive effect. Eating well overall reduces overall risk, but it does not appear to fully offset the specific harm from UPFs.
What counts as a 10% increase in UPF intake?
Lead author Dr. Barbara Cardoso explained that a 10% increase in UPF intake is roughly equivalent to adding a standard packet of chips to your daily diet. At the study's baseline (41% of energy from UPFs), this is a modest and easily achievable reduction in either direction.
Was memory affected in this study?
The study did not find a statistically significant association between UPF intake and memory. The affected cognitive domains were visual attention and mental processing speed. However, experts note that attention decline often precedes memory changes in early cognitive aging, making it a meaningful early warning signal.
How can I reduce my ultra-processed food intake?
The most effective changes are usually the highest-frequency ones: replacing packaged snacks with whole fruits, nuts, or vegetables; swapping sweetened beverages for water; choosing minimally processed proteins (eggs, fish, legumes, poultry) over processed meats; and cooking more meals from whole ingredients. Even modest reductions — replacing one daily UPF with a whole-food alternative — can meaningfully shift intake.
