A new study published in the journal Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring has found that eating ultra-processed foods is associated with declines in attention and mental processing speed. Notably, the association held even among people who otherwise followed a healthy diet, a finding that experts say adds an important wrinkle to how we think about nutrition and brain health.
Researchers from Monash University, the University of São Paulo and Deakin University analyzed data from more than 2,100 middle-aged and older Australian adults. Participants underwent cognitive testing and filled out questionnaires about their food intake. On average, they consumed about 41% of their daily calories from ultra-processed foods, just shy of the Australian national average of 42%.
What Are Ultra-Processed Foods?
Ultra-processed foods include products like packaged cookies, soft drinks, frozen ready-made meals and other items that have undergone extensive industrial processing far beyond basic cooking or preservation. Unlike fresh or minimally processed foods, they often contain additives, emulsifiers, artificial flavors and preservatives not found in a home kitchen.
For every 10% increase in ultra-processed food consumption — roughly equivalent to adding a standard bag of chips to your daily diet — there was a measurable decline in cognitive function and an increase in dementia risk factors. The findings may not translate directly to the United States, where the average daily calorie intake from ultra-processed foods is 55%, compared to 42% in Australia.
Expert Reactions
“I found the study compelling because it suggests that food processing itself may matter for brain health, not just the nutritional label,” said Dr. Shaheen Lakhan, a neurologist not involved in the study. “What stood out most was that the association with attention persisted even among people who otherwise followed a Mediterranean-style diet.”
He believes we may need to look beyond categories like calories, fat, sugar and protein and pay attention to the effects of industrial processing. “You can’t necessarily salad your way out of a heavily ultra-processed diet,” Lakhan said. “Healthy foods remain enormously important, but they may not completely offset the biological effects of highly processed products.”
Neuropsychologist Sanam Hafeez was similarly struck by the persistence of the association. “That suggests food processing itself may have effects beyond simply lacking nutrients,” she noted. “I was also surprised by how relatively small increases in ultra-processed foods were linked to measurable differences in attention.”
How Ultra-Processed Foods May Harm the Brain
Experts point to several overlapping pathways. “The brain is one of the most metabolically demanding organs in the body, so it is particularly vulnerable to chronic inflammation, vascular injury and metabolic dysfunction,” Lakhan explained. “Ultra-processed foods may contribute through several overlapping pathways. They are associated with obesity, hypertension, insulin resistance and cardiovascular disease, all of which are established risk factors for cognitive decline and dementia.”
“Beyond that, processing can alter the food matrix itself and introduce additives, emulsifiers and packaging-related chemicals that may affect the gut microbiome, inflammation and ultimately brain function,” he added.
Dr. Michael Stanley, a neurologist and assistant professor at Tufts University School of Medicine, noted: “High-temperature processing generates compounds known as advanced glycation end-products (AGEs), which have been implicated in damage to blood vessels and other tissues, including those of the nervous system. Certain chemicals, including bisphenol A, or BPA, can also migrate from plastic containers into food.”
He emphasized that the full picture is cumulative. “Diets rich in ultra-processed foods seem capable of sustaining a low-grade inflammatory state throughout the body. While less dramatic than the inflammation associated with infection or injury, this persistent background activity may, over time, contribute to neuronal damage and accelerate processes associated with aging of the brain.”
Stanley also pointed to the role of vascular health, high sodium content, lack of fiber and nutrients, insulin resistance, and disruption of the gut microbiome as additional mechanisms.
Dietary Recommendations for Brain Health
“Diet is one of the few dementia risk factors that people can meaningfully influence every single day,” Lakhan said. “We can’t change our genetics, but we can change what’s on our fork.”
The experts recommend the Mediterranean diet and the MIND diet as examples of whole food approaches linked to lower risk for Alzheimer’s and dementia. “What’s good for the heart is good for the head,” Stanley said. “The Mediterranean diet focuses on eating lots of fruits, vegetables, whole grains, fish and olive oil, and has been shown to lower the risk of memory problems and dementia. The MIND diet takes this a step further by zeroing in on foods that are especially good for the brain — particularly berries and green leafy vegetables like spinach and kale — while also limiting red meat, fried foods, butter and sweets.”
Dr. Zaldy Tan, director of the Cedars-Sinai Health System Memory and Aging Program Neurology, noted that the study reinforced the limits of even a healthy diet when ultra-processed food intake remains high. “Diets that are rich in antioxidants, polyphenols, vitamins, minerals and healthy fats, like olive oil can decrease inflammation and be protective of the brain. But even for people who have decent MIND diet scores, when they had high intakes of ultra-processed food, it still affected their attention.”
“For years, we’ve focused on what healthy foods to add. This study raises the possibility that what we remove may be just as important,” Lakhan noted. “Someone can have a salad for lunch and salmon for dinner, but if a substantial portion of their daily intake comes from ultra-processed foods, there may still be consequences.”
Practical Tips and Caveats
“Stay on the outer aisles where it’s refrigerated because those are perishable items,” Tan said. “The ones in the center typically have very long shelf lives because they’re ultra-processed, with lots of preservatives, salt and sugar added. It’s important to tip the balance toward less processed foods rather than ultra-processed ones.”
However, experts caution against overinterpreting the findings. “I encourage limiting highly processed foods rather than focusing on perfection,” Hafeez said. “I also think it’s important not to jump to conclusions from one study. There could be other factors involved that we do not fully understand.”
“This information is suggestive of an association, not necessarily causation,” Tan echoed. “It doesn’t mean that consuming ultra-processed foods is necessarily the cause of the findings because it could be that consumption of ultra-processed food is also tied to other unhealthy behaviors. And these types of studies are observational and based on food recall with frequency questionnaires, so there could be some inherent recall bias.”
Focus on Attention
The study’s focus on attention, rather than memory, is significant. “Attention is the brain’s gateway function,” Lakhan said. “If attention falters, memory, learning, decision-making and problem-solving often suffer downstream. A useful analogy is that memory gets most of the headlines, but attention is often the operating system running in the background.”
“Attention varies more from a day-to-day standpoint than memory does,” Tan said. “It can be affected acutely by, say, a rise in blood sugar — you get that sugar rush and then crash. Memory doesn’t get affected as quickly. Also the participants were relatively young, so you don’t expect their memory to be significantly affected yet. But attention may be affected even in young people.”
Experts say context matters when evaluating attention lapses. “Occasional lapses in attention are normal and happen to everyone. Stress, poor sleep, anxiety and even multitasking can affect focus,” Hafeez said. “However, persistent changes in attention can sometimes signal a deeper issue. People should pay attention to whether concentration problems are becoming more frequent or interfering with daily life.”
“Attention difficulties can sometimes precede more obvious cognitive symptoms,” Lakhan said. “People should pay attention to persistent changes such as increased distractibility, difficulty following conversations, trouble completing familiar tasks or needing substantially more effort to stay focused than before.”
Stanley recommended tracking patterns over time and consulting a doctor when in doubt. Ultimately, the study underscores the importance of overall health-promoting habits. “The less food is engineered in a factory, the more likely it is to support the organ that makes us who we are,” Lakhan said. “The biggest takeaway is that brain health is built meal by meal, year by year, often long before symptoms appear. This study doesn’t mean that eating a bag of chips will cause dementia. What it suggests is that small, repeated dietary choices may accumulate over decades and influence how our brains age.”
