Cutting salt intake may protect against Alzheimer's

Significantly reducing salt intake could have a preventative effect when it comes to Alzheimer's disease, according to a new study.

A team led by Dr Constantino Iadecola at Cornell University used both a mouse model and human cells to examine the impact of a high-salt diet over time.

In the study report published in the journal Nature Neuroscience, they said a diet that regularly exceeded the daily recommended salt intake resulted in an increase in the number of immune cells called TH17 in the blood following a trigger response from the intestines.

This then boosted a chemical these cells produce called IL-17, which has an inflammatory effect and also suppresses the production of nitric oxide in the blood vessels.

Nitric oxide is known to assist in the relaxation of blood vessels and also contributes to the formation of new memories in the hippocampus.

After just a few days on the high-salt diet, it was found that the mice had experienced a reduction in blood flow to the brain. They had also altered behaviourally, forgetting how to build a nest, struggling to recall objects and becoming unable to find their way out of a simple maze.

Importantly though, the findings of damage were also true for human cerebral endothelial cells, suggesting diet can play an important function in keeping the brain healthy.

When the diet was reversed and the mice were given normal food, their blood flow and endothelial function returned to healthy levels again within four weeks.

Dr Iadecola said the study indicates a "gut-brain axis" that link dietary habits to long-term health and suggested a change in lifestyle could protect the brain in the long term.

It has long been known that the presence of toxic plaques called beta-amyloids is a marker of Alzheimer's in the brain tissue, but this study came about because Dr Iadecola wanted to investigate why the blood vessels in the brains of patients also frequently do not look 'normal'.

New drugs that block IL-17 may therefore be able to reverse some symptoms of Alzheimer's in the future before they even show up, the medic believes.

Dr Sara Imarisio of Alzheimer's Research UK said: "The findings highlight the importance of cutting out excess salt in our diets, as well as identifying possible new avenues in the search for treatments to help those with memory problems or dementia."

Despite accounting for only two per cent of the body's weight, the brain requires around 15 per cent of its total blood supply in order to remain healthy.

Changes in the brain can occur up to ten years before a person starts to display symptoms of Alzheimer's or other degenerative brain conditions. Currently around 60 per cent of people diagnosed with dementia will have Alzheimer's, the most common form of the condition among over-65s.

Figures recently released for 2016 showed that dementia is the biggest threat to human life in this country, beating even heart disease. 

Care homes with trained staff can help to ensure that people with the illness are safe and well looked after, with living spaces specially designed and adapted for those with dementia. Until a cure is found, this is perhaps the best way to help sufferers live independently for as long as possible.