Dementia is an umbrella term for a collection of symptoms associated with brain damage by diseases, which tends to affect people over the age of 65, although it is not a natural part of ageing. While there is no certain way to ward off dementia, research is increasingly suggesting a healthy lifestyle can help reduce a person’s risk of developing dementia. The growing consensus among experts is that what is good heart is also good for the brain, which also means the dietary decisions that are bad for the heart may also be harmful for the brain.
The new study advances research published last year in Nature Neuroscience by Dr. Faraco and senior author Dr. Costantino Iadecola, director of the Feil Family Brain and Mind Research Institute and the Anne Parrish Titzell Professor of Neurology at Weill Cornell Medicine.
The 2018 study found that a high-salt diet caused dementia in mice, showing that the rodents became unable to complete daily living tasks such as building their nests and had problems passing memory tests.
After ruling out the theory that high salt intake was restricting blood flow in the mice, the researchers posited that high salt consumption may cause tau proteins in the brain to become unstable.
The protein tau is known to form tangles in the areas of the brain important for memory and then move through the brain as symptoms progress, and increasing evidence suggests this process may be an underlying trigger of brain decline.
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Although further research on salt intake and cognition in humans is needed, the current mouse study is a further warning sign to regulate salt consumption, Dr. Iadecola said.
He continued: “And the stuff that is bad for us doesn't come from a saltshaker, it comes from processed food and restaurant food.
"We've got to keep salt in check. It can alter the blood vessels of the brain and do so in a vicious way."
In addition to high-salt consumption, inactivity is another risk factor for heart disease that may also increase a person’s risk of developing dementia.
As Alzheimers UK reports, the findings show that regular exercise can significantly reduce the risk of developing dementia by about 30 percent, and for Alzheimer's disease specifically, the risk was reduced by 45 percent.
One particular study looked at health behaviours of over 2,000 men in Wales, and followed them for 35 years.
Of the five behaviours that were assessed (regular exercise, not smoking, moderate alcohol intake, healthy body weight and healthy diet), exercise had the greatest effect in terms of reducing dementia risk.
Overall, people who followed four or five of the above behaviours were up to 60 percent less likely to develop dementia.