Eating too much salt can ’cause build-up of toxic clumps in the brain linked to dementia’

EATING three times your daily recommended amount of salt can cause toxic clumps to form in the brain that are linked to dementia, the latest research suggests.

Researchers gave mice a salt-heavy diet and monitored the build-up of a protein called tau in their brains.

Tau is thought to play a role in the development of Alzheimer’s although it also helps keep nerve cells in their proper shape.

The researchers at Weill Cornell Medical College in New York found the mice performed worse when tested on their cognitive abilities.

However the academics warned that further tests needed to be carried out to see if the same high-salt diet had the same impact on humans.

Adults should consume no more than 6g of salt a day, according to the NHS, the equivalent of one teaspoon, which contains 2.4g of sodium.

In the trial two-month-old mice were fed a diet over a 36-week period which was eight per cent sodium.

Mice usually consume less than one per cent of sodium in their diet on a daily basis, according to the researchers writing in the journal Nature.

The amount given to the mice would be the equivalent of a human eating five times an adult’s recommended daily amount.

The team then carried out brain scans on the animals to monitor how the levels of tau changed over time.

Researchers found the protein began to build up at the four-week mark and then continue to rise.

After just 12 weeks the mice struggled to recognise objects and had trouble finding their way through a maze.

The results indicated the mice suffered from a narrowing of the small blood vessels deep inside their brains, which prevented nutrients from being transported between cells.

Co-lead author Professor Costantino Iadecola said: “The results identify a previously unknown pathway linking dietary habits and cognitive health.

“They indicate that avoiding high-salt diets could maintain cognitive function.

“Our data provide a previously unrecognised link between dietary habits, vascular dysfunction and tau pathology.”

While Dr Evangeline Mantzioris, programme director of nutrition and food sciences at the University of South Australia, praised the “important” research she also added a note of caution, saying: “We cannot with certainty say the same effect would happen in humans”.

Professor John Funder, a neuroscientist at the University of Melbourne, also added a note of caution.

He said: “Any extrapolation from mice on a salt intake of eight per cent to the human situation may be cute, but it is grossly irresponsible in terms of science.”

Lowering your salt intake can also help reduce your blood pressure which significantly reduces brain power loss and may protect against dementia.

Scientists found it cut risk of cognitive decline – an early sign of Alzheimer’s – in older people by a fifth.

Loss of brain power – also known as cognitive impairment – is one of the first signs of dementia.

Those affected find it harder to think, remember and reason, compared to normal people their age.

Around 850,000 Brits have dementia and the figure is expected to hit one million with a decade.

There is currently no cure but some drugs can control the symptoms.