Food Intake and Dementia Risk Link Discovered in Epidemiological Studies and Clinical Trials

Recent medical reports said clinical research attempting to associate specific diets or nutrients with cognitive function had not discovered convincing evidence.

Any person searching for brain-healthy foods online will find no shortage of stories that make dietary recommendations, a EurekAlert! report said.

Some of these stories cite observational studies that have suggested an association between the greater intake of some foods and the risk of dementia.

A lot of trials have not found that making people exercise or eat healthy is translating into advantages in the ways that are expected from the epidemiological research, associate professor of medicine and neurology Hussein Yassine from the Keck School of Medicine of USC and the Kenneth and Bette Volk Chair of Neurology of USC, explained.

He added that there is no causal link or that these studies have not been appropriately designed.

Epidemiological Studies Vs. Clinical Trials

Yassine led the Nutrition for the Dementia Prevention Working Group to understand the difference between epidemiological studies and clinical trials. This research team spent two years investigating the existing literature on nutrition and the risk of dementia.

The team's analysis, published in The Lancet Healthy Longevity, identifies major limitations to present trials that affect how nutrition impacts the brain and provides recommendations to guide and enhance future studies.

In this work, supported by a grant from the National Institute of Health, Yassine points out that generally, nutrition research is difficult to execute well.

Epidemiological studies reveal, for instance, a link between people who eat fatty seafood like salmon and a lower chance of developing dementia.

Healthy Diet Affecting Cognition

However, it is difficult to separate nutritional information from other factors that may play a role as well, like where an individual resides, concurrent healthy lifestyle, or if they have access to proper medical care.

Most of the clinical research on food and brain health may not have been carried out over a period of time, long enough for outcomes to be meaningful because it is unknown how long it takes for a healthy diet to impact cognition.

According to Yassine, if it takes a year to a decade, then studies that lasted for two years or less precisely reflect the impact of the diet on cognition.

Future studies will also improve if more studies are done to understand the amount of a specific nutrient an individual needs, to achieve optimal brain health.

For instance, an accepted vitamin D level sustains bone and health, although the same cannot be said for nutrients believed to affect cognitive health.

Efficacy of Technology

Technology, including brain imaging, can be extremely effective in tracking changes in the brain over time.

Similarly, they're pointing out that testing stool or blood samples for some biomarkers like suboptimal intake of a particular nutrient can also be used to both select the best participants and help determine if study participants are responding to the intervention under research.

Additionally, genetic testing can be an effective mechanism, as well, explained Yassine, who's studying apolipoprotein E4, or APOE4, the strongest genetic risk factor "for late-onset Alzheimer's disease."

A similar Bioengineer.org report also noted that those with this genetic variant respond differently to diet compared to non-carriers. Here, genetic testing can enhance the quality of research with more customized interventions.

Related information about brain food and brain health is shown on UC Davis Health's YouTube video below:

Check out more news and information on Diet and Dementia in Science Times.