• The Listener
  • North & South
  • Noted
  • RNZ

The link between cardiovascular health and dementia

Photo/Getty Images

New research into the brain has found that cardiovascular ill health is linked to cognitive decline and dementia.

The healthier your heart, the healthier your brain, according to the latest science. There is increasing evidence to show that older people who are in bad cardiovascular shape have a greater chance of developing dementia. And now we are beginning to get a clearer picture of exactly why this is.

At the Centre for Cognitive Ageing and Cognitive Epidemiology at the University of Edinburgh, researchers have been examining the MRI scans of thousands of people, aged between 44 and 79, enrolled in the UK Biobank Study. This large-scale project aims to scan the vital organs of 100,000 participants and supply researchers with a valuable resource to increase knowledge and help improve the health of future generations.

“I’m really interested in characterising brain ageing,” says principal investigator Simon Cox. “How is it that some people arrive in their seventies having brains that look like they could be 40 years old, whereas others have pretty stark levels of brain shrinkage? What are the factors that determine that? And how do you end up being one of the people who has virtually no brain change?”

Macro alias: ModuleRenderer

What Cox has been looking at, specifically, is the effect on the brain of a number of factors that influence the health of our blood vessels, such as smoking, high blood pressure, obesity and diabetes. These have all been linked to complications in blood flow to the brain.

A healthy, young brain fits neatly inside the cranial cavity, cushioned by a layer of cerebrospinal fluid. As we age, the cortex or outer layer of the brain thins and its gyri (hills) and sulci (valleys) recede to be replaced by more spinal fluid.

Cox found shrinkage of grey matter was greater in those with high vascular-risk factors. Those same people also had more damage to their white matter, which is the connective tissue of the brain and basically its communications system.

The more risk factors a participant had, the poorer their brain health. Those at highest risk had about 18ml less grey matter (Cox compares that to a little less than a travel-sized toothpaste tube) and one and a half times the damage to white matter.

Simon Cox. Photo/Supplied

The areas affected were mainly those that have been linked to more complex thinking skills and that show changes as a result of dementia and Alzheimer’s disease.

Cox stresses there are likely to be a large number of things that affect the way our brains age. Some we can do nothing about, such as our genes. If you have the APOE4 allele, which is linked to increased risk and earlier onset of Alzheimer’s, unfortunately you are stuck with it.

“But there’s a lot of interest in malleable lifestyle factors, the things you can do something about.”

He advocates a marginal gains approach, getting big results from lots of small changes, as popularised by British cycling coach Dave Brailsford, who helped his team to victory by making hundreds of small improvements. Maintaining healthy blood pressure, body weight and blood sugar, and not smoking, should be just some of the things we do to stave off dementia.

“Because the associations were just as strong in midlife as they were in later life, it suggests that addressing these factors early might mitigate future negative effects,” says Cox.

More evidence for the far-reaching benefits of a healthy heart was provided last year by a large French study of people aged over 65. It used the American Heart Association’s Life’s Simple 7 prevention strategy, which covers diet, smoking, cholesterol, blood sugar, blood pressure, physical exercise and weight. Those with the best cardiovascular scores had the lowest rates of cognitive decline and dementia.

And, last year, US researchers working with mice found that exercise to improve cardiovascular fitness improves blood flow to white matter and protects against dementia.

“There are lots of other excellent reasons to ensure we’re in good cardiovascular health,” says Cox. “This is perhaps another motivation.”  

This article was first published in the May 11, 2019 issue of the New Zealand Listener.