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Hot dogs and other processed foods can have an impact on cognitive function, researchers say. Ivan/Getty Images
  • A new study concludes that regular consumption of ultra-processed foods raises a person’s risk of cognitive decline.
  • In an earlier study, Australian researchers also reported that ultra-processed foods can negatively impact cognitive functions.
  • These foods include packaged snacks and pre-prepared dishes such as pizza and pies.
  • These studies line up with previous research that indicates that an unhealthy diet can impair cognitive abilities and raise the risk of dementia-related diseases such as Alzheimer’s.

New research indicates that regularly consuming ultra-processed foods such as hot dogs and frozen pizza can raise your risk of cognitive decline.

In a study published today in the journal JAMA Neurology, researchers looked at more than 10,000 individuals over a median period of 8 years.

They concluded that people whose daily calorie intake is at least 20% from ultra-processed foods had a 25% faster decline in executive functions and a 28% faster rate of overall cognitive impairment.

The researchers noted that if a person’s overall diet quality was high, the effect of ultra-processed foods was less.

“While this is a study of association, not designed to prove cause and effect, there are a number of elements to fortify the proposition that some acceleration in cognitive decay may be attributed to ultra-processed foods,” Dr. David Katz, a specialist in preventive and lifestyle medicine and nutrition, told CNN.

“The sample size is substantial and the follow-up extensive. While short of proof, this is robust enough that we should conclude ultra-processed foods are probably bad for our brains,” he added.

The new findings are in line with another study published in July in the European Journal of Nutrition that also suggested that consuming ultra-processed foods may have a negative impact on cognitive performance in older adults.

The researchers from Australia conducting the study told Healthline they defined ultra-processed foods as those that undergo “several industrial processes that can’t be reproduced at home.”

They noted that these items contain little to no whole foods and typically include flavorings, colorings, emulsifiers, and other cosmetic additives.

Examples include packaged snacks, chocolates, breakfast cereals, and pre-prepared dishes such as pies, pasta, and pizza.

That’s opposed to processed foods that the researchers defined as foods that commonly have added sugar, oil, or salt. The processing is used to increase the durability or enhance the “sensory qualities” of the food. Examples include canned veggies, fruits, legumes, and salted, cured, or smoked meats.

Another study published in the journal Neurology also reported that people who consume high amounts of ultra-processed foods such as sodas, chips, and cookies may have a higher risk of developing dementia.

Using a cross-sectional study, the team of Australian researchers evaluated more than 2,700 participants who were 60 years or older.

The participants were part of the National Health and Nutrition Examination Survey from 2011 to 2014. Each participant recalled what they ate in a 24-hour period on two nonconsecutive days.

The team used standardized, validated tests, including one that assesses Alzheimer’s disease. They concluded that consuming ultra-processed foods was associated with worse performances in one of the tests among older people who did not have pre-existing diseases.

Researchers told Healthline the findings suggest that decreasing ultra-processed foods may be a way to improve impaired cognition among older adults.

“Research indicates that diets that follow a Mediterranean Diet style, recognized by the high proportion of foods with anti-inflammatory and antioxidant properties, are associated with a reduced risk of age-associated cognitive decline and dementia,” said Barbara Cardoso, Ph.D., lead author of the study and a senior lecturer in nutrition, dietetics, and food at Monash University in Melbourne, Australia.

“Foods consumed as part of these diets include fish, nuts, olive oil, and vegetables,” she said.

Experts say these findings are consistent with what they’ve learned from other studies about diet and dementia.

“There is growing evidence that what we eat can impact our brains as we age and many studies suggest it is best to eat a heart-healthy, balanced diet low in processed foods and high in whole, nutritional foods like vegetables and fruits,” said Percy Griffin, Ph.D., director of scientific engagement for the Alzheimer’s Association.

“So, it’s not surprising that this paper found that a diet high in ultra-processed foods impaired cognition in older adults,” he told Healthline.

Another study published in the journal Neurology last year also suggested there were benefits from a Mediterranean diet on brain health.

The researchers concluded that their findings corroborated the view that a Mediterranean diet could be a ”protective factor against memory decline and mediotemporal atrophy,” or shrinkage of the lobe of the brain associated with Alzheimer’s.

The Centers for Disease Control and Prevention estimates that nearly 6 million people in the United States have Alzheimer’s and related dementias.

By 2060, the number of people diagnosed with Alzheimer’s is predicted to rise to an estimated 14 million.

Communities of color could be affected the most. Cases among Hispanics could increase seven times over the current estimates. Among African Americans, cases could increase four times the current estimates.

In San Francisco, a new community-based program is designed to focus on known modifiable risk factors to help prevent dementia.

Posit Science along with the YMCA is launching a model “Brain Health Program” funded by the National Institutes of Health.

The program, which is expected to be in operation in 6 months, will offer classes to at-risk adults. Part of the training will focus on the diet and nutrition principles the YMCA has been using in its Diabetes Prevention Program.

“Eating a brain-healthy diet is a big part of the Brain Health Program,” said Henry Mahncke, Ph.D., the chief executive officer of Posit Science.

“The future of brain health and dementia prevention is changing what we do in our everyday life so we build healthy, resilient brains that keep going as long as our bodies keep going,” he told Healthline. “Just about everything we eat gets sent by the bloodstream up to our brains, and so it’s not surprising to brain health experts that what we eat matters for our brain health, our cognitive performance, and our risk of dementia.”

The Australian researchers say their study is the first to investigate the association between ultra-processed foods and cognitive decline.

“As such, it sheds light for future studies that aim at providing stronger evidence unraveling potential mechanisms involved,” said Cardoso.

She explained the study had some limitations. It looked at a specific point in time whereas it may take years for impaired cognition to develop. They relied on participants to recall their dietary intake, which might not always be an accurate representation of their usual dietary intake.

“The next step for this research is to study if reducing the amount of ultra-processed foods in one’s diet could improve cognition,” said Griffin.

He noted that there will be more research on the impact of an unhealthy diet on dementia risk introduced at the upcoming Alzheimer’s Association International Conference that begins July 31.