We already know too much salt can lead to stroke and heart disease. But could it also affect your mind?

Scientists found that a high salt diet caused cognitive impairments in mice, and it could be the same for humans.

Costantino Ladecola, director of the Feil Family Brain and Mind Research Institute at Weill Cornell Medicine in New York, said they fed the mice eight to 16 times their normal salt intake.

They then tested the mice using behavioural tests, and it did not take long for researchers to observe the effect of a high salt diet on mice.

“After about three months, the mice became demented,” Dr Ladecola said.

“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 research, published in the latest edition of Nature Neuroscience, suggested humans would experience a similar response.

Studies have shown Australians eat around double the recommended amount of salt each day, most of it coming from processed food.

Dr Ladecola said the estimated two teaspoons of salt the average Australian eats each day could affect brain function over the long term.

However, 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,” Dr Ladecola said.

‘You are what you eat’

While a high salt diet has already been linked to brain diseases such as stroke and dementia, the question has long been why?

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 dysfunction.

“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.

Professor Vissel said it was part of a growing body of evidence that we really are what we eat.

“There’s no question now that what you eat affects your gut in a number of ways,” he said.

“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.”

– ABC