High or Low Blood Pressure May Raise the Risk of Dementia

Blood Pressure Alzheimer's

October 8, 2019

Maintaining a healthy blood pressure in midlife may be important for helping to reduce the risk of Alzheimer’s disease and other forms of dementia in old age, new research shows. The findings underscore the connection between heart health and brain health and show how maintaining a healthy blood pressure may help to keep memory and thinking skills sharp in old age.

In one study, researchers at Johns Hopkins tracked more than 4,761 men and women for about 25 years. They ranged in age from 45 to 65 at the start of the study, and got their blood pressure checked regularly. By the end of the study, when participants were in their 70s, 80s or 90s, 516 had developed Alzheimer’s disease or other forms of dementia.

The researchers found that those with high blood pressure at midlife — in their 40s, 50s or early 60s — were 49 percent more likely to develop dementia late in life than those with normal blood pressure at midlife or in old age. Those who had high blood pressure in middle age but low blood pressure late in life were at even greater risk of developing dementia: Their risk of dementia increased by 62 percent compared to those with a healthy blood pressure.

High blood pressure was considered any measurement more than 140/90, whereas low blood pressure was defined as less than 90/60.

“Our results suggest that one’s blood pressure during midlife may influence how blood pressure later in life relates to dementia risk,” said Keenan Walker, assistant professor of neurology at the Johns Hopkins School of Medicine and an author of the study, which was published in JAMA. “We found that individuals with high blood pressure in midlife may benefit from targeting their blood pressure to normal levels in later life, as having blood pressure that is too high or too low in late life may further increase dementia risk.”

In a separate British study, researchers report that having high blood pressure around age 40 was tied to a smaller brain size at age 70. A smaller brain size has been linked in other studies to an increased risk of Alzheimer’s disease and other forms of dementia. The study, which followed hundreds of British citizens over many years, found that high blood pressure in middle early age was also associated with brain abnormalities indicative of early dementia. The findings were published in Lancet Neurology.

Earlier studies had found that various heart risk factors at midlife are also risk factors for Alzheimer’s disease. In addition to high blood pressure, being overweight, smoking, leading a sedentary life or having diabetes can all increase your risk of developing dementia years down the road.

Some 75 Americans have high blood pressure, also called hypertension. It can arise because of genetic factors, but also because of lack of exercise and a poor diet (e.g. alcohol and salt [sodium] have great consequences on high blood pressure). Getting regular exercise and eating a heart healthy diet can help to keep blood pressure in check.

Doctors also often prescribe medications to control blood pressure. Studies have shown that intensive blood pressure lowering may reduce the risk of mild cognitive impairment, or MCI, a brain condition that causes memory and thinking problems. In many cases, people with mild cognitive impairment go on to develop Alzheimer’s disease or other forms of dementia.

Studies also suggest that men and women who take drugs to keep blood pressure in check may be somewhat protected against Alzheimer’s disease and other types of dementia. If you are prescribed blood pressure drugs, it is important to keep taking them to keep blood pressure in check and improve your health over all.

Sources: Keenan A. Walker, PhD; A. Richey Sharrett, MD, DrPH, Aozhou Wu, PhD, MHS, et al: “Association of Midlife to Late-Life Blood Pressure Patterns With Incident Dementia.” JAMA Vol 322 (6), pages 535-545, August 13, 2019.

Shyam Prabhakaran, MD, MS: “Blood Pressure, Brain Volume and White Matter Hyperintensitives, and Dementia Risk.” JAMA, August 13, 2019.

Lane C, et al: “Associations Between Blood Pressure Across Adulthood and Late-Life-Brain-Structure and Pathology in the Neuroscience Substudy of the 1946 British Birth Cohort (Insight 46): An Epidemiological Study, Lancet Neurology, July 2019.


Alzheimer's Articles