After months of feeding mice 8-16 times their daily salt intake, scientists found that brain function rapidly deteriorated.
Experiments on mice and human cells have revealed that consuming too much salt can leave the subject “demented”.
Costantino Iadecola, director of the Feil Family Brain and Mind Research Institute at Weill Cornell Medicine in New York, said his team fed the mice between eight and 16 times more salt than their normal intake and the results were staggering.
“After about three months, the mice became demented,” Dr Iadecola said.
After about three months, the mice became demented.
“Mice are very curious and they like to look for new things, and so over time the mouse lost the ability to identify a normal object.
“When put in their cage and asked to find a quiet spot, the mouse did not remember where the quiet spot was.
“Then when the mouse was building a nest, which is something the mouse does daily, they were unable to do so.”
The study, published in Nature Neuroscience, states salty foods trigger an inflammatory immune response that deprives the brain of oxygen and harms neurons, resulting in behavioural and mental problems. And it suggests humans are also vulnerable to cognitive deterioration with excessive salt consumption.
However, Dr Iadecola says the decline might not be as aggressive as they saw in the mice, who were given extremely high levels of salt.
“But probably over years and perhaps decades — as opposed to a few months for the mouse — even lower levels of salt may have a devastating effect,” he said.
Importantly, the study also showed that the effects could be reversed with a return to a normal diet.
Professor Bryce Vissel, director of the centre for neuro science at the University of Technology Sydney, said this latest study showed “very elegantly” how salt caused cognitive impairments.
The link between inflammation and brain dysfunction is very clear.
“It shows that it is doing it by causing profound immune changes in the gut resulting, in effect, in an almost autoimmune effect on the brain,” he said.
“There’s no question now that what you eat affects your gut in a number of ways,” he added. “Those changes in the gut in turn cause all sorts of responses in the body, some of those are inflammatory and those responses over time certainly contribute to brain dysfunction.
“The extent to which it actually leads to things like dementia we don’t know, yet but the link between inflammation and brain dysfunction is very clear.”