Blood pressure is usually discussed as a measure of heart health, but it may also provide important clues about the brain.
Research from the University of Miami suggests that the lower number in a blood pressure reading may be linked to brain changes that affect thinking, movement and stroke risk.
A blood pressure reading contains two numbers. Systolic pressure, the top number, is measured when the heart pumps. Diastolic pressure, the bottom number, is measured while the heart relaxes between beats.
Doctors have traditionally paid particular attention to systolic pressure, especially in older adults. However, the study suggests that diastolic pressure may also be important when considering the health of small blood vessels in the brain.
The researchers focused on white matter lesions, also known as white matter hyperintensities. These are areas of damage that appear as bright spots on certain brain scans and become more common as people grow older.
White matter contains nerve fibers that connect different parts of the brain and allow them to communicate. Damage in these areas has been associated with problems involving memory, thinking, walking and balance, as well as a greater risk of stroke and dementia.
The University of Miami team studied more than 1,200 adults aged 50 and older. Researchers compared participants’ blood pressure measurements with brain scans to see whether blood pressure was associated with the amount and location of white matter damage.
People with lower diastolic blood pressure had fewer white matter lesions in certain parts of the brain than those with higher readings. In particular, diastolic pressure below 80 mmHg was associated with less damage than readings of 90 mmHg or higher.
The relationship was especially noticeable in a region called the periventricular white matter. This tissue is located near fluid-filled spaces in the brain and contains important pathways used for communication between brain regions.
The finding is interesting because systolic blood pressure has often received more attention in research on aging and cardiovascular disease. The study suggests that the second number in a blood pressure reading should not simply be ignored.
High blood pressure can damage small blood vessels over many years. When these vessels become narrowed or injured, parts of the brain may receive less healthy blood flow, which may contribute to the development of white matter lesions.
These changes are often silent and may be discovered only when a person has a brain scan for another reason. Their presence does not necessarily mean someone will develop dementia or have a stroke, but a greater burden of white matter damage has been linked to poorer brain health.
The research was led by Michelle R. Caunca and colleagues at the University of Miami Miller School of Medicine. The findings were published in the journal Stroke, a scientific publication of the American Heart Association.
The study cannot prove that lowering diastolic blood pressure will directly prevent white matter damage. It shows an association, and other health factors may also influence both blood pressure and changes in the brain.
Blood pressure also should not be pushed too low without medical guidance. Very low pressure can cause dizziness or fainting in some people and may be especially concerning for older adults who are vulnerable to falls.
Still, the research adds to evidence that healthy blood vessels are important for healthy aging of the brain. Managing high blood pressure through appropriate treatment, physical activity, a balanced diet and other healthy habits may protect much more than the heart.
Regular blood pressure checks can help people identify hypertension before it causes obvious symptoms. Anyone with consistently high or unusually low readings should discuss them with a healthcare professional, who can recommend a target based on the person’s age and overall health.
If you care about stroke, please read studies about how to eat to prevent stroke, and diets high in flavonoids could help reduce stroke risk.
For more health information, please see recent studies about how Mediterranean diet could protect your brain health, and wild blueberries can benefit your heart and brain.
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