- High blood pressure is a known risk factor for developing dementia.
- Researchers recently identified the specific areas of the brain that may be damaged by high blood pressure and are linked to the development of dementia.
- Further studies may help researchers identify patients at high risk of cognitive impairment.
More than 55 million people globally have dementia — an umbrella term for a number of diseases causing memory loss and cognitive decline.
While scientists are still not sure what causes dementia, they know certain conditions may impact whether a person develops dementia or not. One of these is high blood pressure.
Previous research shows people with high blood pressure have a greater risk of developing dementia, including Alzheimer’s disease.
Now, researchers from the University of Edinburgh in the U.K. and Jagiellonian University Medical College in Krakow, Poland, have discovered the specific areas of the brain that may be damaged by high blood pressure and are linked to the development of dementia.
The study was recently published in the European Heart Journal.
What is blood pressure?
A person’s blood pressure is the amount of force the heart uses to pump blood through the arteries.
When the doctor takes your blood pressure, they get two different numbers. The top number measures the systolic pressure when the heart pumps blood out of the heart and into the arteries. The bottom number measures the diastolic pressure when the heart rests between heartbeats. Both are measured in millimetres of mercury (mmHg).
For example, normal blood pressure is less than 120mmHg systolic pressure and less than 80mmHg diastolic pressure (but more than 90mmHg systolic and 60mmHg diastolic).
When the systolic pressure creeps into the 130s and diastolic pressure into the 80s, that is considered the start of high blood pressure. Anything over 140mmHg systolic pressure and 90mmHg or higher diastolic pressure is stage 2 high blood pressure.
What is high blood pressure?
High blood pressure — clinically known as hypertension — occurs when the force blood needs to move through the arteries becomes too high.
This can happen if the arteries become damaged or narrower due to cholesterol-containing plaque inside the walls of the arteries.
Certain factors may increase a person’s risk for developing high blood pressure, including:
- unhealthy diet
- smoking and/or alcohol use
- certain diseases such as diabetes
How does high blood pressure affect the brain?
According to Prof. Tomasz Guzik, professor of cardiovascular medicine at the University of Edinburgh in the U.K. and Jagiellonian University Medical College in Krakow, Poland, and the lead author of this study, having high blood pressure can harm the structure and function of the brain in different ways.
“For instance, hypertension can severely impact the blood vessels in your brain, leading to their reshaping, hardening, and the development of clogged arteries. When blood pressure is elevated, the increased pressure is transmitted from larger blood vessels to smaller ones in the brain, leading to their dysfunction and a condition known as small vessel disease,” he told Medical News Today.
“[When blood pressure is elevated] this not only affects the blood supply to the brain but also enhances pathological processes such as inflammatory activation and neurodegeneration. These factors contribute to dementia, memory loss, and impairment of various cognitive functions.”
— Prof. Tomasz Guzik
Additionally, Prof. Guzik said, high blood pressure can also damage the white matter in the brain.
“The white matter is composed of nerve fibers that transmit information between different brain regions, and damage to this area can lead to impaired cognitive function and increase the risk of stroke,” he explained.
“This highlights the importance of monitoring and managing blood pressure levels to prevent damage to the white matter and associated cognitive impairments,” he said.
The hypertension-dementia link
For this study, Prof. Guzik and his team used a combination of magnetic resonance imaging (MRI) of brains, genetic analyses, and observational data from thousands of participants of the UK Biobank, COGENT, and the International Consortium for Blood Pressure.
Upon analysis, researchers identified changes in nine areas of the brain related to high blood pressure and worsened cognitive function.
These areas include the putamen responsible for learning and motor control. Previous research links dysfunction of the putamen to Alzheimer’s disease.
Other areas impacted by high blood pressure included the white matter areas, the anterior thalamic radiation, anterior corona radiata, and the anterior limb of the internal capsule.
The anterior thalamic radiation is involved in planning and executing both simple and complex behaviors, while the anterior corona radiata helps support decision-making and management of emotions. And the anterior limb of the internal capsule assists with cognitive processing, motivation, and decision-making.
Will this help assess future disease risk?
Prof. Guzik said the next step in this research will be to design clinical trials and studies focused on imaging the brain areas his research team identified to see if their assessment can help in identifying patients at high risk of cognitive impairment.
“This can provide clinicians with novel tools for future-oriented precision medicine diagnostic and therapeutic approaches. Looking closer at these brain areas can also tell us much more about how (the) brain functions in the condition of hypertension and identify new ways of improving this function,” he said.
After reviewing this research, Dr. Raphael Wald, a neuropsychologist at Marcus Neuroscience Institute, part of Baptist Health, told Medical News Today it would be helpful for clinicians if similar studies could lead to a formal set of guidelines and protocols for identifying individuals at risk for stroke.
“This can become another tool that doctors have to assess a person’s risk for stroke. We can also use this information as a means of detecting specific types of strokes depending on how patients present. It will also allow us to look further into ways to protect these areas of the brain when they are at risk,” he said.
Not a coincidental correlation
Medical News Today also spoke with Dr. Sandra Narayanan, a vascular neurologist and neuro-interventional surgeon at Pacific Stroke & Neurovascular Center at Pacific Neuroscience Institute in Santa Monica, California, about this study.
She pointed out that high blood pressure is a modifiable finding and said research suggests that the dysregulation of blood pressure, white matter disease phenomena, and cognitive dysfunction go hand-in-hand, and are not coincidental.
“Knowing that it’s a modifiable risk factor for cardiovascular disease can help primary care providers, cardiologists, neurologists, and other health care providers adequately advise patients and families to get this risk factor very aggressively under control,” Dr. Narayanan explained.
“We know that high blood pressure, like a lot of other medical conditions, is not optimally controlled either from the beginning or during the course of that patient’s lifespan, much less during the course of the day. So in many patients, it requires not just [one] medication, it requires sometimes multiple medications to control [the] patient’s blood pressure,” she added.
And, Dr. Narayanan said, lowering high blood pressure may also require control of a person’s other medical conditions.
“An example is someone who has a comorbid vascular condition, diabetes, (or) obesity. Controlling those other medical conditions — losing weight for example — can cause better blood pressure control. And co-managing those other medical conditions with honest conversation and frequent check-ins can really benefit the long-term cognitive performance and lifespan quality of life of these patients,” she detailed.
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