Brain damage caused by high blood pressure could contribute to dementia

Scientists have identified the regions of the brain that are damaged by high blood pressure and may contribute to the development of dementia.

Experts said the finding is a “step forward in our understanding of the concerning link between high blood pressure and cognitive decline”.

It is the first time these regions have been identified by scientists. Experts will now look at the specific parts of the brain in more detail with a view to finding new ways to treat mental decline among people with high blood pressure.

In the future, academics hope that the findings will help predict memory loss and dementia.

Researchers studied analysis of brain scans, genetics and data from thousands of patients.

Their findings were then checked against another group of patients in Italy.

Lead author Tomasz Guzik, professor of cardiovascular medicine at the University of Edinburgh and Jagiellonian University Medical College in Krakow, Poland, said: “By using this combination of imaging, genetic and observational approaches we have identified specific parts of the brain that are affected by increases in blood pressure, including areas called the putamen and specific white matter regions.

Memory loss and thinking skills

“We thought these areas might be where high blood pressure affects cognitive function such as memory loss, thinking skills and dementia.

“When we checked our findings by studying a group of patients in Italy who had high blood pressure, we found that the parts of the brain we had identified were indeed affected.

“We hope that our findings may help us to develop new ways to treat cognitive impairment in people with high blood pressure.

“Studying the genes and proteins in these brain structures could help us understand how high blood pressure affects the brain and causes cognitive problems.

“Moreover, by looking at these specific regions of the brain, we may be able to predict who will develop memory loss and dementia faster in the context of high blood pressure.”

Prof Guzik added: “This could help with precision medicine, so that we can target more intensive therapies to prevent the development of cognitive impairment in patients most at risk,” he said.

High blood pressure has previously been linked to dementia and damage to brain function but the new study, published in the European Heart Journal, shows for the first time exactly how it causes damages and the specific regions affected.

The international team of researchers examined MRI scans from more than 30,000 people taking part in the UK Biobank study.

They also looked at genetic information from UK Biobank participants as well as people involved in two separate studies.

They identified changes to nine parts of the brain related to high blood pressure and worse cognitive function.

These included decreases in brain volume, changes to connections between different parts of the brain and changes in measures of brain activity.

The regions which appeared to be affected include a round structure in the base of the front of the brain called the putamen, responsible for regulating movement and influencing learning.

Other areas affected include regions of white matter that enable signalling between different parts of the brain.

Specific brain regions at high risk

They involve the planning of simple and complex daily tasks, decision making and the management of emotions.

Co-author Prof Joanna Wardlaw, head of neuroimaging sciences at the University of Edinburgh, said: “It has been known for a long time that high blood pressure is a risk factor for cognitive decline, but how high blood pressure damages the brain was not clear.

“This study shows that specific brain regions are at particularly high risk of blood pressure damage, which may help to identify people at risk of cognitive decline in the earliest stages, and potentially to target therapies more effectively in future.”

Prof James Leiper, associate medical director at the British Heart Foundation, which funded the research, said: “Researchers have taken a significant step forward in our understanding of the concerning link between high blood pressure and cognitive decline.

“The nine brain areas identified can become nine new points of focus for further research.

“Cognitive decline can be very debilitating and scary for those patients suffering from it.

“By continuing to improve our understanding of how the changes in these brain areas affect cognitive function, we could potentially find new ways of stopping many people with high blood pressure from having to experience it.”

Dr Timothy Rittman, senior research fellow at Alzheimer's Research UK, added: “High blood pressure is very common and, if untreated, can increase the risk of certain forms of dementia in later life.

“This study starts to unravel the reasons why this is by using sophisticated statistical methods to draw a link with problems with memory and thinking and, for the first time, shrinkage in specific parts of the brain.

“It could lead to new ways to measure the damage that blood pressure has on the brain, which could have a very big impact in helping reduce dementia risk.

"That's because, if the early signs of damage to the brain could be spotted early, we can potentially slow this down with better blood pressure monitoring and treatment.

"This research also underlines how crucial it is to treat it to keep our brains healthy as we age."

In a separate study, researchers developed a form of the omega-3 fatty acid docosahexaenoic acid (DHA) that is capable of crossing into the eye's retina to ward off sight loss related to Alzheimer's disease, diabetes and other disorders.

The DHA found in fish oil capsules and other supplements is typically in a form called triacylglycerol (TAG) DHA.

While this has benefits in other parts of the body, it does not reach the eyes because it cannot travel from the bloodstream.

Researchers created a new form of DHA, or LPC-DHA and tested the supplement in mice bred to exhibit processes similar to those found in early-onset Alzheimer’s.

After six months of daily supplements, the mice showed a 96 per cent improvement in retinal DHA content as well as preserved retinal structure and function.

The findings were presented at the annual meeting of the American Society for Biochemistry and Molecular Biology, in Seattle.