A peer-reviewed study published this week in Alzheimer’s & Dementia, the journal of the Alzheimer’s Association, has found that eating more ultraprocessed foods raises the risk of dementia and measurably damages attention — even in people who otherwise follow healthy, plant-rich diets. The finding carries direct implications for tens of millions of American households where packaged snacks, sugary drinks, and convenience meals now make up the majority of daily calories.
What the Study Found
The study, published in Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring, examined the diets and cognitive health of more than 2,100 Australian dementia-free adults who were middle-aged and older. The findings demonstrate that a slight daily increase in a person’s intake of ultraprocessed foods is linked to a measurable drop in attention span — even if someone otherwise eats healthy.
Researchers from Australia’s Monash University analyzed more than 2,000 dementia-free adults between the ages of 40 and 70, comparing their diets to cognitive function. They found that each 10% increase in ultraprocessed food intake was associated with lower attention scores and higher dementia risk, regardless of whether the adults typically followed a healthy diet, like the Mediterranean diet.
The study also identified a broader pattern of harm. Ultraprocessed food consumption is linked to over 30 adverse health outcomes, including several risk factors for dementia such as cardiovascular disease, type 2 diabetes, and obesity.
Study lead author Barbara Cardoso, a senior lecturer of nutrition dietetics and food at Monash University in Melbourne, Australia, stated: “Our study showed that UPF consumption was associated with worse attention and higher dementia risk in middle-aged and older adults.” She noted the study could only show an association, not direct cause and effect. However, “this association was not changed by adherence to the Mediterranean diet, indicating that this is linked to food processing rather than simply food displacement.”
Why Attention — Not Just Memory — Matters
One of the study’s more significant findings is that attention, not memory, was the cognitive function most clearly affected. In clinical terms, this translated to consistently lower scores on standardized cognitive tests measuring visual attention and processing speed.
Attention emerged as particularly vulnerable — an early casualty that impairs learning, decision-making, and problem-solving long before memory deficits appear. Researchers characterize this as a critical public health signal: the damage is measurable in the middle decades of life, well before the age at which most Americans begin thinking about dementia prevention.
No significant association was found between ultraprocessed food consumption and memory directly. The findings suggest that food processing itself may play a role in cognitive decline and highlight the need to refine dietary guidelines, the researchers said.
The U.S. Is Among the Most Exposed Nations
For American readers, the relevance of an Australian study is direct. Ultraprocessed foods make up about 53% of all calories consumed by adults in the United States, according to the latest data from the U.S. Centers for Disease Control and Prevention. Children in the United States obtain nearly 62% of their energy from ultraprocessed foods.
Those numbers give the Monash findings particular urgency for American families. The study examined a population where approximately 42% of diets come from ultraprocessed foods — well below what American households currently average. If the risk relationship holds, U.S. consumption patterns may carry even steeper cognitive consequences than what the study was designed to detect.
The Dementia Burden Is Already Escalating
The study arrives alongside a parallel warning from the Alzheimer’s Association itself, published just weeks earlier. An estimated 7.4 million Americans age 65 and older currently live with clinical Alzheimer’s dementia — a number that could increase to 13.8 million by 2060, absent medical breakthroughs that prevent or cure the disease. Total payments in 2026 for health care, long-term care, and hospice services for people age 65 and older with dementia are estimated to reach $409 billion.
Nearly all adults ages 40 and older (99%) say maintaining brain health is at least as important as physical health, yet only 9% say they know a lot about how to maintain it. That gap between stated priority and practical knowledge is exactly what the Monash study addresses.
What the Science Says About Ultraprocessed Food and the Brain
Ultraprocessed foods — packaged snacks, sugary drinks, ready-to-eat meals, and most items with lengthy ingredient lists — undergo industrial treatments that strip away natural structures while adding sugars, unhealthy fats, additives, and chemicals. These alterations promote inflammation, insulin resistance, oxidative stress, and poor blood flow, all documented contributors to brain deterioration.
Multiple large-scale studies, including analyses from the UK Biobank and the Framingham Heart Study, have linked higher intake of ultraprocessed foods to accelerated cognitive decline, increased Alzheimer’s risk, and higher incidence of vascular dementia. One analysis estimated that replacing just 10% of these products with unprocessed or minimally processed alternatives could reduce dementia risk by nearly 20%.
The Bottom Line for Americans
The Monash study adds peer-reviewed weight to a body of evidence that points in a consistent direction: the contents of a typical American grocery cart are not neutral where brain health is concerned, and the damage begins accumulating in midlife — not just in old age.
Researchers noted the study relied on self-reported data, which may limit the strength of the conclusions. Larger longitudinal studies tracking individuals over time are needed to establish causation. But the signal in the data is consistent enough that researchers say it already warrants action at the level of dietary guidelines.
The practical recommendation emerging from the research is straightforward: whole foods — fruits, vegetables, lean proteins, legumes, nuts, and whole grains — in place of packaged and processed alternatives. For a nation where more than half of daily calories already come from a box, a bag, or a drive-through window, that guidance asks for a significant shift. The new data makes the stakes of that shift harder to ignore.
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