Scientific evidence shows that diets high in ultra-processed foods are associated with an increased risk of dementia, including Alzheimer’s disease and vascular dementia, as well as cognitive decline and mild cognitive impairment.

Ultra-processed foods are often high in unhealthy fats, salt, and added sugar or artificial sweeteners, like sucralose and aspartame. They also often contain artificial additives and preservatives. These foods often lack essential nutrients and fiber, which are important for brain health. A diet rich in fruits, vegetables, whole grains, lean proteins, and healthy fats has been associated with a reduced risk of dementia.

Some studies suggest that a diet high in ultra-processed foods may indirectly contribute to dementia risk by promoting chronic conditions such as obesity, diabetes, and hypertension, which are known risk factors for cognitive decline. Consuming high amounts of ultra-processed food (UPF) may also lead to chronic inflammation, oxidative stress, and alterations in gut microbiota, which could also negatively impact brain health.

Americans are among the highest consumers of ultra-processed food in the world; more than half of our calories come from UPFs. 

This fact sheet is organized into sections that highlight research between ultra-processed foods and all-cause dementia, Alzheimer’s disease, and cognitive decline.  

What is the scientific evidence linking ultra-processed foods and all-cause dementia?

All-cause dementia refers to any type of dementia, including but not limited to Alzheimer’s disease, vascular dementia, and Lewy body dementia.

A 2022 prospective cohort study was published in Neurology and included the data of more than 700,000 people in the United Kingdom. After examining ultra-processed food consumption and various forms of dementia, the researchers found: “In the fully adjusted model, consumption of UPF was associated with higher risk of dementia, Alzheimer’s disease, and vascular dementia, respectively. In addition, replacing 10% of UPF weight in diet with an equivalent proportion of unprocessed or minimally processed foods was estimated to be associated with a 19% lower risk of dementia.” 

In a 2024 systematic review of observational studies published in the Journal of Neurology, researchers investigated the link between UPF consumption and dementia, including Alzheimer’s disease, vascular dementia and mild cognitive impairment. The data of more than 800,000 individuals across several continents were included. The results showed “High (vs. low) intake of UPF was associated with increased risk of dementia , although moderate (vs. low) intake of UPF was not.” The researchers concluded: “Our findings highlight the contributory role of UPF consumption to the development of dementia and that co-ordinated global and national public health policies and clinical guidelines are needed to displace consumption of UPFs with fresh, minimally processed, easily affordable food, to tackle the societal burden of dementia.”

What is the scientific evidence linking ultra-processed foods and Alzheimer’s disease?

In a 2024 review published in Frontiers in Nutrition, researchers sought to examine the connection between eating ultra-processed foods and Alzheimer’s disease risk. The research included 5 cohort studies and the data of more than 617,000 people. The researchers found, “of the included studies, 4 demonstrated a risk association between the consumption of ultra-processed foods and the development of Alzheimer’s disease, while 1 study showed a risk association only with the development of cognitive decline.” The authors concluded: “Although there have been few studies on the topic so far, the included studies have a longitudinal design with robust results. Our findings reinforce the importance of public strategies aimed at raising awareness among the population about the harmful effects of UPF consumption on cognitive health.”

In an ecological study published in 2023 in PLoS ONE, researchers investigated, among other associations, the link between diet and Alzheimer’s disease in a Brazilian population. They used data from databases related to the rate at which drugs for the disease were prescribed, along with data related to nutrition and food security. Researchers found “significant” associations between ultra-processed food consumption and Alzheimer’s disease.

What is the scientific evidence linking ultra-processed foods with cognitive decline or mild cognitive impairment?

A prospective study published in JAMA Neurology in 2022 examined the self-reported data of more than 10,000 people in an “ethnically diverse” Brazilian cohort to investigate links between ultra-processed foods and cognitive decline. All research subjects were free of cognitive impairment at baseline, and “changes in cognitive performance over time evaluated by the immediate and delayed word recall, word recognition, phonemic and semantic verbal fluency tests, and Trail-Making Test B version.” In a median follow-up of 8 years, researchers found that “individuals with ultraprocessed food consumption above the first quartile showed a 28% faster rate of global cognitive decline and a 25% faster rate of executive function decline compared with those in the first quartile.” They noted that decline in cognition and executive function could be “related to systemic inflammation caused by the consumption of UPF, because increased levels of circulating proinflammatory cytokines have been associated with cognitive decline.” On the other hand, “healthy dietary patterns were associated with higher gray and white matter volume, total brain volume, and Aβ42/40 ratio, as well as lower oxidative stress and inflammation.” The researchers concluded: “Limiting UPF consumption, particularly in middle-aged adults, may be an efficient form to prevent cognitive decline.”

In a study published in Neurology in 2024, researchers sought to investigate the association between ultra-processed food consumption and cognitive impairment and stroke. More than 14,000 study participants were included in the cognitive impairment cohort.  The researchers found that “a 10% increase in relative intake of UPFs was associated with higher risk of cognitive impairment and intake of unprocessed or minimally processed foods with lower risk of cognitive impairment.”

In a cross-sectional analysis published in 2023 in the European Journal of Nutrition, researchers examined the data of more than 3,600 people from the U.S. over the age of 60. The data included self-reported questionnaires related to diet, along with several cognitive performance assessments. Researchers found that “UPF consumption was significantly associated with worse performance in Animal Fluency in older adults without pre-existing diseases.” Animal Fluency is a common test used to assess mild cognitive impairment and Alzheimer’s disease, in which patients are asked to name as many animals as possible in 60 seconds. An early sign of dementia or Alzheimer’s disease may be when a patient answers fewer than 15 animals in the time frame. The study authors concluded: “While longitudinal studies are required to provide stronger evidence, these results suggest that decreasing UPF consumption may be a way to mitigate age-associated cognitive decline and reduce the risk of dementia.”

In 2012, a study examined the eating patterns of 249 elderly people with mild cognitive impairment (MCI). The research, published in Nutrients, compared the participants’ diets of whole foods, which included a high intake of vegetables, legumes, fruit, whole grain, fish, egg, low fat dairy, and nuts, versus processed foods, which included foods high in saturated fat, high-fat dairy, potatoes, refined grains, sweetened beverages and red and processed meat. Participants’ cognitive function was measured with the measure known as the Cambridge Cognitive Examination (CAMCOG). Researchers found that “participants in the highest tertile of the processed food pattern score were more likely to have poorer cognitive functioning [and be] in the lowest tertile of executive function.”

What is dementia? 

Dementia is an umbrella term that refers to the “impaired ability to remember, think, or make decisions that interferes with doing everyday activities,” according to the CDC. The most common type of dementia is Alzheimer’s disease, which makes up 60 to 80% of all dementia cases. Other common types of dementia include vascular dementia, Lewy body dementia, frontotemporal dementia, and Creutzfeldt-Jakob disease. Symptoms can significantly range according to severity and dementia type, but they can include behavioral changes, memory loss, difficulty problem solving, confusion, hallucinations, language complications, and more. 

Journalism and opinion

Dementia risk may increase if you’re eating these foods, study says, by Sandee LaMotte, CNN, Dec. 5, 2022

Bad diet causes cognitive decline: Fact or myth? by Fred Schwaller, Deutsche Welt, Dec. 12, 2022

Dementia risk: Ultra-processed foods may accelerate cognitive decline, by Anna Guildford, PhD, Medical News Today, Dec. 6, 2022

Eating processed ultra-processed foods tied to cognitive decline, by Heidi Godman, Harvard Health Publishing Mind & Mood, April 1, 2023

Read our other fact sheets on the studies that link ultra-processed foods to other severe health risks, including cardiovascular disease, depression, Type 2 diabetes, addiction, cancer, obesity, and premature death. Also, see our fact sheets on the health risks of the artificial  sweeteners sucralose and aspartame.