Diet and Dementia Risk: New Food for Thought

Damian McNamara

April 24, 2020

The combination of foods individuals consume may influence dementia risk as much as which foods they eat, new research suggests.

Investigators from the University of Bordeaux in France examined "food networks" and found that individuals whose diets consisted mainly of highly processed and starchy foods were significantly more likely to develop dementia than those whose diets also included processed foods and incorporated a wider variety of healthy foods.

"These findings are in accordance with previous work from our group and many others on diet and cognitive health. However, the novelty here is on the emphasis that how foods are consumed and combined ― and not only the quantity consumed ― may be important for dementia risk," lead investigator Cecilia Samieri, PhD, told Medscape Medical News.

The study was published online April 22 in Neurology.

Novel Network Approach

The current findings align with multiple previous studies that show strong associations between specific food groups and the risk for cognitive aging and dementia.

For example, the Mediterranean diet, which emphasizes high intake of plant foods and low consumption of meat and dairy, among other factors, is associated with lower risk for cognitive impairment and Alzheimer disease.

Similarly, the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet ― which promotes intake of berries, green leafy vegetables, and other plant-based foods and limits consumption of saturated fat and animal foods ― has also been linked to a lower risk for dementia.

However, Samieri noted that much of this previous research focused on quantity and frequency of foods.

"Our study went one step further to look at food networks and found important differences in the ways in which food items were co-consumed in people who went on to develop dementia and those who did not," she said in a release.

Using "network science," the investigators assessed the complex interplay between different foods, and in some cases alcohol and other drinks, when consumed together.

Participants came from the 3-City study, an ongoing population-based cohort on dementia launched in 1999–2000. It includes 9294 noninstitutionalized community-dwelling adults older than 65 years from Bordeaux, Dijon, and Montpellier, France.

Baseline data included sociodemographic and lifestyle characteristics, medical information, neuropsychological testing results, blood pressure and anthropometric measurements, and findings from blood samples.

A comprehensive dietary survey was conducted at the Bordeaux site in 2001–2002. It included a qualitative food frequency questionnaire and a 24-hour dietary recall assessment administered in a face-to-face interview with trained dieticians.

Diet Diversity Important

The nested case-control study included 1522 persons who participated in the dietary survey and baseline dementia screening. The average age of the participants was 78 years, 74% were women, and 62% were educated at the secondary school level or higher.

At 12-year follow-up, 215 participants developed dementia. A total of 209 participants were each matched with two control persons (n = 418).

The researchers found that although there were few differences in the amount of foods individuals ate, overall food networks differed substantially between case participants and control persons.

The food network, or "hub," in those who developed dementia was "strong and focused" and was characterized by what the investigators describe as "charcuterie," which consists of highly processed meat as well as potatoes and other starchy foods, other meats, alcohol, and highly processed snacks.

"In contrast," the researchers note, "the network of controls was more diverse and included several disconnected subnetworks reflecting generally healthier food choices."

Alcohol consumption in both groups was relatively high; on average, participants consumed nine drinks per week.

Overall, the investigators add, "this application of network approaches to dietary risk factors in dementia suggests that a more diverse diet may be particularly favourable and that diets focused on processed meats, potatoes/starchy food and unhealthy snacks may be associated with dementia risk many years later."

Samieri said the findings are likely generalizable to "many populations around the world," although this needs to be confirmed by future studies in specific countries.

The study's strengths include its large population and long follow-up. Limitations include potential errors in self-reported food intake and assessment of diet at only one time point.

Cause for Pause?

"I found it interesting," Donn D. Dexter, MD, told Medscape Medical News when asked to comment on the study. "It serves to reinforce the many articles that have shown a clear relationship between a heathy diet, particularly the Mediterranean or MIND diets, and improved cognitive functioning.

"There are a couple interesting findings in the patient population that give me pause," added Dexter, a neurologist at the Mayo Clinic Health System Northwest, Wisconsin Region in Eau Claire, and a fellow of the American Academy of Neurologists.

A study population of almost 75% women, for example, seems somewhat skewed, even in an elderly cohort, he said.

"I was also impressed by the alcohol use in this population. They report nine servings...of alcohol in both the control and patient groups. So, I am not sure how well this study represents my patients."

Funding was provided by multiple agencies, including the Fondation pour la Recherche Medicale, the French National Research Agency COGINUT, the Fondation Plan Alzheimer, the Caisse Nationale pour la Solidarite et l’Autonomie, and the Alzheimer Association. The 3C study is conducted through a partnership among INSERM, the University of Bordeaux, and Sanofi-Aventis. Samieri and Dexter have disclosed no relevant financial relationships.

Neurology. Published online April 22, 2020. Abstract

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