Midlife diets high in ultra-processed foods linked to cognitive complaints in later life

Women who consume more ultra-processed foods during midlife face a higher likelihood of experiencing memory and thinking difficulties later in life, according to a new study published in Preventive Medicine. The research found that those with the highest intake of these foods were about 20 percent more likely to report subjective cognitive complaints in their later years compared to those with the lowest intake. These findings raise concerns about the potential long-term impact of diet on brain health.

Alzheimer’s disease and related forms of dementia affect millions of people in the United States, with women accounting for roughly two-thirds of diagnosed cases. Identifying early indicators and modifiable risk factors is an urgent public health priority. One such early warning sign is subjective cognitive complaints, which refer to a person’s own perception of memory or cognitive difficulties. Research indicates that these self-reported problems may reflect subtle changes in brain function and could precede clinical signs of dementia by several years.

Ultra-processed foods are increasingly being investigated for their links to health problems. These products, typically made from highly refined ingredients and industrial additives, now make up over half of the daily caloric intake in many high-income countries. Previous research has connected them to conditions such as heart disease and diabetes.

There is also growing interest in whether diets high in these foods might affect brain health. However, most studies have focused on older adults or clinical outcomes, such as diagnosed dementia, rather than early cognitive symptoms. This new study aimed to fill that gap by examining the relationship between midlife consumption of ultra-processed foods and the risk of later-life cognitive complaints.

“We have been interested in how diet and midlife lifestyle factors can influence aging and late-life disease. We have a cohort of women recruited in 1985 and prospectively followed to date,” said study author Yu Chen, a professor of epidemiology at the NYU Grossman School of Medicine.

The researchers used data from the New York University Women’s Health Study. It included over 14,000 women who were between 35 and 65 years old at the time of enrollment. For this specific analysis, the team focused on 5,119 women who were still alive and had completed follow-up questionnaires about their cognitive health in 2018 or 2020, roughly 25 to 35 years after they joined the study.

At the start of the study, participants provided detailed information about their diets through a food frequency questionnaire. The researchers classified the reported foods according to the “NOVA” system, which categorizes foods based on the extent of processing. Ultra-processed foods include items such as packaged snacks, reconstituted meat products, ready-to-eat meals, and sweetened dairy desserts. Beverages were not included due to limitations in the dietary questionnaire.

To assess cognitive health later in life, participants answered six questions about changes in memory and mental function, such as difficulty remembering a short list or following conversations. Women who reported at least two of these issues were considered to have significant cognitive complaints.

After adjusting for factors like age, education, body weight, smoking, alcohol consumption, physical activity, and health history, the researchers found a pattern: the more ultra-processed food a woman consumed in midlife, the more likely she was to report cognitive complaints in later life. Specifically, women in the highest fifth of ultra-processed food intake had 24 percent higher odds of reporting two or more cognitive complaints compared to those in the lowest fifth. This association remained consistent even when applying statistical techniques to account for missing data or potential selection bias.

“Women who consume a lot of ultra-processed food during midlife are 20 percent more likely to have subjective cognitive complaints in later life, indicating worse cognitive function,” Chen told PsyPost. “The findings are consistent with the literature that a higher level of fat intake in the diet is related to the risk of Alzheimer’s disease.”

The analysis also looked at different types of ultra-processed foods. Dairy products with high levels of processing, such as flavored yogurts and processed cheeses, were linked to a greater risk of cognitive complaints. Processed meats and fast foods also showed associations, though these were less pronounced. Interestingly, no strong association was found for sugary foods or sauces when considered independently, once other variables were controlled.

Even after removing women who had been diagnosed with Alzheimer’s disease or related dementias from the analysis, the association between midlife ultra-processed food intake and late-life cognitive complaints remained. This suggests the findings may apply to women without diagnosed neurodegenerative conditions and could reflect earlier stages of brain health changes.

Like all observational studies, this one cannot determine cause and effect. While the researchers adjusted for many factors that could influence both diet and cognition, there may still be unmeasured variables that played a role. For example, the dietary data came from a questionnaire completed decades ago, and such surveys may not fully capture all food items or preparation methods. Beverages, including sugary drinks and processed protein shakes, were not included, which may have underestimated the participants’ total ultra-processed food intake.

“Our food frequency questionnaire may not be comprehensive enough to capture more ultra-processed food products,” Chen noted. “In addition, beverages are not included.”

Another limitation is that the study population included only women, which limits how widely the findings can be applied. Further research is needed to examine whether the same patterns hold in men or in more diverse groups.

The authors note that future studies should include more detailed dietary assessments and explore specific ingredients in ultra-processed foods that may impact the brain. It may also be helpful to study biological mechanisms, such as how processed food affects inflammation or the gut microbiome, both of which have been linked to cognitive function.

“We hope to identify modifiable lifestyle risk factors in midlife that impact late-life cognition,” Chen said. “Interventions or health education can be designed accordingly.”

The study, “Association between midlife intake of ultra-processed foods and later-life subjective cognitive complaints: Evidence from the new York University women’s health study,” was authored by Kejia Zhang, Fen Wu, Tess V. Clendenen, Yelena Afanasyeva, Yian Gu, Karen L. Koenig, Anne Zeleniuch-Jacquotte, and Yu Chen.