Here is another reason to reduce intake of salt.

High levels of dietary salt can activate a pathway in the brain to cause cognitive impairment, according to a new study. The paper, which was published in Nature, shows that this effect is not due to a loss in blood flow to the brain as originally thought, but rather to clumps of a protein linked to several forms of dementia in humans. The research was funded by the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health.

In a family of diseases called tauopathies, it is these tau aggregates that interfere with the proper function of brain cells, which can lead to cognitive impairment and eventually dementia. When mice consumed the high-salt diet in this study, their brains also showed evidence of tau aggregates that coincided with reduced cognitive abilities.

The researchers further showed that tau was the important factor behind these effects by studying mice that had their gene for tau deleted. These mice showed a similar drop in brain blood flow, but because they could not make tau protein, they did not form tau aggregates, nor did they show a decrease in their cognitive abilities. Similar results were observed with an antibody against tau.

“The take-home message here is that is that while there is a reduction in blood flow to the brains of mice that eat a high-salt diet, it really is tau that is causing the loss in cognitive abilities. The effect of reduced flow really is inconsequential in this setting,” said Dr. Iadecola.

Although Dr. Iadecola points out that the salt content consumed by the mice in this study is eight to 16 times higher than normal and is likely to be more than a person would consume in a single day, their findings provide important links between diet, the blood vessels of the brain, and cognition… (Excerpts from NIH, October 23, 2019)

 Dr KK Aggarwal

Padma Shri Awardee

President Confederation of Medical Associations in Asia and Oceania (CMAAO)

Group Editor-in-Chief IJCP Publications

President Heart Care Foundation of India

Past National President IMA