The dietary pattern used for this research was the MIND diet, which combines aspects from the Mediterranean diet and the DASH diet. The DASH diet was originally developed to lower blood pressure, whilst the MIND diet was specifically developed to maintain brain health as we age. The dietary pattern emphasises, amongst other things, green leafy vegetables, berries, whole grains, nuts, legumes and olive oil.
“The MIND diet consists of different food groups that you should either eat more of or eat less of,” says Remie. “Think of more berries, vegetables and nuts, and less red meat, fried food and sweets. The aim of this study was to gain a better understanding of how this dietary pattern might be linked to processes involved in cognitive decline.”
Diet, inflammation and brain health
Previous observational studies show that people who adhere to the MIND diet often have better cognitive performance and a lower risk of dementia. However, it remains largely unknown how adherence to the diet leads to these effects. Remie: “There are various theories about the involved mechanisms. A key hypothesis is that diet influences inflammatory processes in the body which play a role in brain ageing.”
In the study, the researchers analysed data from 88 participants aged between 60 and 75 who were at increased risk of cognitive decline based on their lifestyle. They investigated the relationship between the MIND diet, inflammation markers in the blood, inflammatory processes in the brain and cognitive performance.
No direct link, but an important difference
The researchers initially expected to find a direct link: for example, that people who eat more healthily have lower inflammation levels or a better cognitive performance. However, they did not find such direct links. “We saw no direct relation between the MIND diet and inflammation markers or cognitive performance,” says Remie. “But when we looked further, we discovered something interesting: the diet does appear to play a role in how inflammation in the body relates to processes in the brain.”
Among participants with a lower score on the MIND diet, a clear link was found: higher levels of inflammation in the body were associated with more signs of inflammatory activity in the brain and poorer cognitive performance. “We didn’t see that link in people who scored higher on the diet,” explains Remie. “That could mean that the MIND diet serves as a protective factor. ”
Gut health might play a role as well. The researchers also investigated the permeability of the so-called gut barrier. Higher gut barrier permeability turned out to be associated with more signs of inflammatory activity in the brain, but again only in participants who scored lower on the MIND diet. Remie: “In the group of people with a lower MIND diet score, gut barrier permeability appears to lead to the brain via higher levels of inflammation in the blood.”
Further research needed
Although the results provide interesting clues, Remie stresses that it is still too early to draw firm conclusions. “This is an observational analysis at a single point in time,” she says. “To really know whether diet causally affects these processes, we also need to look at intervention studies.”
The researchers hope that the results will help to better understand how lifestyle, the immune system and brain health are interlinked. “Our research shows that diet may influence how inflammatory processes in the body affect the brain,” says Remie. “That is an important step towards understanding how we might be able to slow down cognitive decline.”