High blood pressure damages the brain – and can even cause dementia

Researchers have discovered for the first time how high blood pressure affects our brain. Accordingly, high blood pressure damages nine brain regions in particular, including some main cable strands between different parts of the brain. The structures involved are important for learning, planning, executive functioning, and decision-making. This explains why high blood pressure can promote cognitive deficits and dementia.

Millions of people are affected by high blood pressure

Millions of people around the world have high blood pressure – often without even knowing it. But that has consequences: If the blood pressure is permanently above 140/90 millimeters of mercury (mmHg), this can damage vessels, the heart and other organs and promote heart attacks, strokes and kidney damage. The brain is also affected: Studies show that high blood pressure increases the risk of mental deterioration and dementia.

But how exactly high blood pressure damages the brain and which areas are particularly affected was previously unclear. “It is very difficult to determine the exact causes and mechanisms behind the link between high blood pressure and mental decline,” explain Mateusz Siedlinski of the Jagiellonian University in Kraków and his colleagues. To answer this question, they used a combination of several imaging, genetic and statistical methods.

This is how the researchers proceeded

For their study, the researchers first evaluated genome data from around 33,000 participants in the UK Biobank study. They looked for gene variants in the genome that promote high blood pressure. In the next step, they analyzed magnetic resonance imaging (MRI) of the test subjects’ brains to find out whether, where and how changes were occurring in the brains of hypertensive patients.

In the final step, they used what is known as Mendelian randomization to link brain scans and genetic findings. “With Mendelian randomization, one can determine the causal link between two characteristics,” explains senior author Tomasz Guzik from the Jagiellonian University. In this specific case, the comparison of risk genes for high blood pressure with the brain changes observed in high blood pressure patients clarifies whether these are really due to the blood pressure.

Stimuli, learning, planning – nine brain areas are particularly affected

The result: “For the first time, our study has identified specific areas in our brain that are causally damaged by high blood pressure and that are closely linked to our mental performance,” says Siedlinski. According to this, nine brain areas in hypertensive patients show a strikingly altered structure and reduced volume. One of these areas is the putamen, a region located at the base of each cerebral hemisphere. “The putamen is part of the basal ganglia and is essential for stimulus response, learning and planning,” explains the team.

Also affected are several parts of our brain’s central conduction system – the bundles of nerve fibers that make up the white matter of the brain. Some of the damaged pathways are responsible for transmitting the sensory information processed in the thalamus to the higher brain function centers in the cortex. Others are important for the correct functioning of the brain areas that we use to make decisions, plan our actions, or control emotions and impulses.

“These results suggest that the impairment of cognitive performance caused by high blood pressure also goes back to these specific parts of the white matter of the brain,” report Siedlinski and his colleagues.

Basis for better early detection and therapy

According to the research team, their findings now help to better understand the effect of high blood pressure on the brain. “By analyzing the genes and proteins in the affected areas of the brain more closely, we can now find out how high blood pressure works there and why this causes the cognitive deficits,” says Guzik. This could help develop more effective therapies for mental decline in hypertensive patients.

At the same time, knowledge of the nine particularly endangered areas of the brain could also contribute to early detection. “By looking at these specific areas of the brain, we could identify earlier which people are at risk of cognitive deficits if they have high blood pressure,” explains Guzik.

Those: European Society of Cardiology

This article was written by Nadja Podbregar