Eating food high in salt may affect mental performance, even if it doesn’t increase blood pressure, a new study has found.
Researchers at Weill Cornell Medicine in New York discovered that mice fed a diet high in salt saw a decrease in blood flow to the brain, and the integrity of their brain blood vessels appeared to be compromised. In addition, performance on cognitive tests was low, the Los Angeles Times reports.
However, these effects did not appear to be a natural result of high blood pressure, as has been widely believed. Rather, they appeared to stem from signals sent by the immune system from the gut to the brain.
This study provides new insights on the links between what people eat and how they think and the role that the immune system plays in the process. The results suggest that even before a consistent high-salt diet pushes blood pressure up, a gut saturated with salt is already independently laying the foundation to compromise tiny blood vessels in the brain, and the network. these vessels form.
The team of researchers found that a high-salt diet brought on an immune response in the small intestines of mice that increased levels of an inflammatory substance called interleukin-17. These high levels prompted a chain of chemical responses inside the lining of blood vessels in the brain.
After feeding mice a high-salt diet, the researchers found that blood supply to the cortex and hippocampus, which control learning and memory, slowed down. As a result, cognitive performance declined. The mice fed a high-salt diet were slower in running through a maze than mice fed a low-salt diet. The mice with more salt in their food also failed to respond normally to whisker stimulation or to new items placed in their cage.
This mental decline was present even without high blood pressure, the researchers found. On the bright side – for the mice, at least – when the high-salt diet was stopped, the cognitive performance returned to normal.
The researchers suggested that if there are drugs or therapies that can disrupt the inflammatory signals coming from the gut before they reach the brain, heart disease and stroke risks might be reduced.
The study was published in Nature Neuroscience.