No link between diet and dementia? Not so fast

Some diets, such as the Mediterranean diet, have sometimes been associated with better cognitive outcomes, but some studies have found no connection between what people eat and their risk of dementia – like the one published in the medical journal JAMA on Tuesday.

"Getting a high score on this scale (…) does not necessarily mean for me that a person is following a healthy diet for the brain," said neurologist Richard Isaacson, director of the clinic's prevention of cancer. Alzheimer's disease of Weill Cornell Medicine and New York-Presbyterian.

Isaacson, who did not participate in the new study, explained that the way she evaluated healthy eating reflected the way doctors thought about what was healthy – as with the now dated food pyramid. He "brings together" foods that are known to be beneficial to brain health, such as green leafy vegetables, with foods such as beans, with an unknown impact, he added.

The author of the study, Tasnime Akbaraly, wrote in an e-mail that the main scale "is based on a set of specific and limited food groups and may not cover all aspects of a" healthy "diet. .. and may not be adapted to the eating habits of all. However, the study showed consistent results over a long period, after people for a median of nearly 25 years. Most observational studies on diet and cognitive health, she added, cover much shorter windows.

But in the new study, it's not as if what people ate was not important. The authors found that healthier diets were associated with lower mortality risks, consistent with previous research.

"Do not highlight the association between average diet and dementia does not mean that diet does not matter in cognitive health," said Akbaraly, researcher at Inserm, the National Institute of Health and Medical Research of the University of Montpellier in France.

The study also revealed a "slight decrease in the quality of diet in the years leading up to the diagnosis of dementia [which] suggests that an unhealthy diet could be part of the series of changes that occurred during the preclinical phase of dementia, "said Akbaraly, also an honorary researcher at University College London.

Isaacson said the research is strong, in a sense, about how long it has followed participants, but it's still important to look at who is being studied for commonalities in diet, exercise, stressors, level of education and other factors that could skew the data in one way or another. L & # 39; other.

In this case, the new study covered over 8,200 London-based officials, more than two-thirds of whom were male and predominantly white. Among them, there were 344 cases of dementia recorded. The study used electronic medical records to identify cases of dementia, which, according to the authors, might overlook less severe cases that have not yet been diagnosed. But it also allowed them to evaluate all the candidates recruited for the study, rather than those who came for follow-up visits.

"We already know that in this cohort, there were marked differences in health according to the social position of public servants, whose highest ranks were in better health and the lower ranks," said Tom. Sanders, professor emeritus of nutrition. Diet at King's College London, said in a statement sent via email.

"What we do not know is the nutritional quality of diets and the link that exists between food choice and other aspects of lifestyle, such as smoking and alcohol consumption" added Sanders. Both of these factors are known to increase the risk of dementia. "

Regarding the risk of dementia, experts say that what you eat is only part of a very complex equation.

"It would be wrong to suggest that the diet at the average age is not important," said Sanders.

"You can not just eat a magic blueberry or follow a certain diet and think that your chances of suffering from Alzheimer's disease will go away," said Isaacson. "People are taking different paths for Alzheimer's disease and dementia."