Measuring blood pressure can be used as a tool to evaluate your overall health and identify if you’re at risk for health conditions like heart disease, heart attacks or strokes. Now, new research published in Alzheimer’s & Dementia suggests it may also be used to indicate your risk for dementia.
Researchers found that fluctuations in blood pressure – known as higher systolic blood pressure variability (BPV) – over time were associated with an increased risk of dementia later in life among adults over 65. However, the authors noted single blood pressure measurements or average blood pressure levels do not seem to be linked with dementia risk in older adults.
However … single blood pressure measurements or average blood pressure levels do not seem to be linked with dementia risk in older adults.
“Such variability in blood pressure may not be healthy, especially for the brain,” Philip Gorelick, MD, MPH, co-author of the study and professor of neurology at the Northwestern University Feinberg School of Medicine, told Seasons.
The researchers also found the connection between systolic BPV and dementia risk was stronger in participants not taking calcium channel blockers, which are certain types of blood pressure-lowering medications.
While blood pressure changes throughout the day – decreasing during sleep and increasing with exercise, for example – these changes can be more extreme in some people than in others, and that amount of variation is what’s meant by “blood pressure variability.” For example, if the systolic blood pressure on one reading was 120 and later was 160, that would indicate variability.
Understanding systolic blood pressure variability
Systolic blood pressure is the top or first number that appears when a health care practitioner measures your blood pressure, and the bottom number refers to the diastolic blood pressure. Systolic blood pressure measures the pressure in your arteries when your heart beats and is generated by the heart when it contracts, pushing blood throughout the body.
Logistics of the study
Gorelick and his colleagues analyzed long-term and visit-to-visit BPV in two groups of older adults, including those in the Rush Memory and Aging Project and the Religious Orders Study.
The authors stated that participants were followed through annual assessments for up to 27 years, and visit-to-visit BPV was quantified over three, six, nine and 12 years. During each annual visit, a research assistant measured the participant’s blood pressure and determined their cognitive status.
They found higher systolic BPV was linked to a subsequent increased risk of dementia later in life and that calcium channel blockers may modify this association.
Links between systolic blood pressure variability and dementia risk
One reason why systolic BPV may increase dementia risk is that the fluctuations could reflect the instability of the autonomic nervous system, said Mitchell Elkind, MD, MS, FAHA, American Heart Association chief clinical science officer.
“The resulting changes in blood pressure over the course of the day may lead to periods of lower blood pressure than optimal or higher than optimal to the brain,” Elkind explained.
He added blood pressure variability has also been associated with strokes (one of the major causes of dementia), along with degenerative causes like Alzheimer’s disease. Furthermore, blood pressure may also cause other changes to the brain structure and function, including increased inflammation.
Further, Gorelick said, fluctuations may affect the brain when blood pressure is elevated. For example, the elevation of systolic blood pressure may be associated with shrinkage of the brain and changes to an area of the brain called the white matter—which is important for conducting brain signals. Also, the brain may be more likely to develop changes consistent with Alzheimer’s.
The role of blood pressure-lowering medications
Elkind said calcium plays an important role in the ability of muscles to contract, but high blood pressure can cause increased contraction or stiffness of the blood vessels through the body and also increase heart contraction. Calcium channel blockers work by blocking calcium entry into cells, helping to reduce the damage caused by excessive muscle contraction.
“Calcium channel blockers affect the influx of calcium into the blood vessel wall causing the blood vessel to relax, resulting in blood pressure lowering,” Gorelick explained.
He added calcium channel-blocking medications have been associated with a lack of blood pressure variability. However, he noted that more studies are needed to better understand the relationships between blood pressure-lowering medications, systolic BPV and dementia risk.
Checking your blood pressure
People without a history of high blood pressure should check their blood pressure annually at a regular health checkup with their physician, Elkind said. On the other hand, caregivers and older adults who believe they have elevated blood pressure or heart problems should connect with their providers to verify that they have high blood pressure.
“There is increasing evidence that monitoring high blood pressure at home, using an approved device, is an effective way to track blood pressure and make lifestyle and medication adjustments, if needed, to control it,” Elkind added.
Once a formal diagnosis is given, experts say patients can talk with their provider about advice on how frequently they should check their blood pressure, lifestyle modifications to potentially lower blood pressure and the possible need for blood pressure-lowering medications, such as calcium channel blockers.
Elkind added if you are checking your blood pressure, a good blood pressure target for many people is now considered to be less than 120 mm Hg systolic and less than 80 mm Hg diastolic. For example, 120/80 mm Hg.
“We call high blood pressure the ‘silent killer’ because it may not cause symptoms or problems until a catastrophic event, like a heart attack or stroke occurs, so it is important to get it checked out quickly,” he added.