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Will Low Blood Pressure Increase the Danger of Dementia in Older People?

Is lower blood pressure always better? Many people think that 120/80 is ideal but older people may be at risk for dementia if diastolic BP goes too low.
Will Low Blood Pressure Increase the Danger of Dementia in O...
Elderly woman pensioner measures the blood pressure itself.

Many physicians believe that a good blood pressure (BP) is right around 120/80, regardless of age. Some aggressively prescribe several blood pressure medicines to achieve that goal. There is, however, some research suggesting that there could be unforeseen complications from low blood pressure in elderly patients.

A study published in JAMA Internal Medicine (Dec. 13, 2021) concluded that

“This cohort study found that dementia risk was lower for older individuals with higher SBP [systolic blood pressure] levels…”

The Guidelines Say Lower Is Better:

A cardiologist once told us that you could not have too low a golf score or cholesterol level. He was certainly correct about golf, but we think he might have been mistaken about cholesterol. It was almost as if he had convinced himself that cholesterol was a colossal mistake of nature. That despite the fact that we could not survive without cholesterol.

There seems to be a somewhat similar belief about blood pressure. Many health professionals seem to think that the lower the BP, the healthier the patient. Certainly throughout middle age hypertension increases the risk for heart attacks, strokes, kidney damage and dementia. That’s why doctors often attempt to “normalize” patients’ blood pressure to 120/80, regardless of age.

The Dangers of Low Blood Pressure in Older People:

When it comes to the elderly, however, low blood pressure numbers may not necessarily be better. In older adults, aggressive BP control may actually lead to several serious side effects. Dizziness is not an unusual complication of drugs that produce low blood pressure. If an older person falls because he is unsteady, that could lead to a fracture. A broken hip can be a life-threatening adverse reaction.

Accelerated mental decline is an additional concern. That was the conclusion from an Italian study of 172 elderly people attending memory clinics (JAMA Internal Medicine, April, 2015). The authors concluded that getting systolic blood pressure below 128 with drugs increased cognitive impairment. They recommended a range of 130 to 145 as more appropriate in the elderly.

New Research and Low Blood Pressure:

This may have seemed heretical to many physicians, but a new study appears to confirm the connection between blood pressure and cognitive function among the oldest old. The latest study in JAMA Internal Medicine (Dec. 13, 2021) challenges the American Heart Association (AHA) and the American College of Cardiology (ACC). These august bodies issued new guidelines earlier this year.

People who are otherwise healthy but have systolic blood pressure between 130 and 140 need to use non-drug approaches initially to lower their BP. Anything above 140/90 requires “pharmacologic therapy.” These guidelines do not take age into account, though.

The latest study (Dec. 2021) found that people over 70 had less dementia when their systolic blood pressure was higher than the AHA and the ACC guidelines permit. You can read all the details at this link.

Research focusing on nonagenarians found that those who developed hypertension late in life–no sooner than 80 and preferably after 90–actually had a lower risk of dementia (Alzheimer’s & Dementia, online Jan. 16, 2017).

The 90+ Study that provided this insight started tracking very old members of a California retirement community in 2003. By 2013, 1,554 people had volunteered for the study. None had dementia when they entered.

The researchers were able to complete a series of semi-annual in-depth in-person neurological exams on 559 of the participants. Those who developed hypertension (pressure above 140/90) after age 80 were 42 percent less likely to be diagnosed with dementia in their nineties. If their blood pressure didn’t rise until after they turned 90, they were 63 percent less likely to experience severe cognitive difficulties.

In Their Own Words:

The researchers concluded:

“In this cohort of oldest-old participants who were free of dementia into their 90s, hypertension onset late in life was associated with a lower dementia risk compared with those with no hypertension.”

Why Is Low Blood Pressure Problematic?

The researchers think that by the time a person reaches an advanced age, higher blood pressure may be protecting rather than harming brain function. They suggest that higher blood pressure may help get more blood and oxygen to the aging brain. Perhaps older bodies are compensating for inadequate blood flow to the brain by boosting blood pressure. This might also offer some protection against disability and physical decline because other organs are also getting better blood flow.

What to Make of All This Research?

The new research will come as a shock to some doctors. But this is not the first time a study has shown cognitive benefit for older adults with elevated blood pressure. The Adult Changes in Thought (ACT) study found a decreased risk of dementia among people who developed hypertension after age 85 (Journal of the American Geriatrics Society, August, 2007).

Lower Blood Pressure and Brain Shrinkage?

Another study offers additional evidence that low blood pressure may pose problems in certain cases (JAMA Neurology, Aug., 2013).  Dutch investigators tracked 663 patients with vascular disease for roughly four years. They had MRI scans at the start of the study and again at the end. The study revealed that people who had low diastolic blood pressure at the onset of the research had the greatest brain shrinkage (atrophy) over time.

Swedish Research on Low Blood Pressure:

Swedish researchers followed 1,270 older adults for six years (JAMA Neurology, Feb., 2003).

The authors reported:

“In this elderly Swedish population, aged 75 years and older, we found that not only high systolic pressure, but also low diastolic pressure, was associated with an increased incidence of Alzheimer disease and dementia. The risk effect of low diastolic pressure on dementia was pronounced particularly among antihypertensive drug users.”

The Take Home Message on Low Blood Pressure:

Perhaps it is time to think about ideal blood pressure as changing throughout life. In fact, our blood pressure changes almost on a minute-by-minute basis depending upon our activities and mental state.

As we get older, especially in our later years, the best blood pressure goal may be a bit higher than 120/80. If an older person has low diastolic blood pressure, adding powerful blood pressure medications may increase the risk for falls and fractures because of dizziness. In addition, it may be bad for the brain.

A Pharmacologist Weighs In:

We received this message from a fellow pharmacologist:

“I am a pharmacologist, recently retired at age 71. In my opinion, the blood pressure guidelines need to be carefully considered in those of us who are healthy, thin and active with a BP in the 140/90 range.

“I think I am more apt to suffer a decrease in my quality of life on BP drugs and will fight any physician who thinks I need to take these meds! What’s more, overmedicated elderly people have a higher incidence of falls, which can be devastating.”

No one should ever stop any medication without careful consultation and monitoring by a physician. This is especially true of some blood pressure drugs that could cause rebound hypertension if discontinued suddenly.

The newest study suggests that those between 70 and 95 were less likely to develop dementia when their systolic blood pressure was above the old cutoff of 130. Doctors need to take fall risk into account when prescribing for older patients.

People who are interested in a variety of strategies for managing hypertension may wish to consult our eGuide to Blood Pressure Solutions. This online resource is available under the Health eGuides tab.

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About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.” .
  • van Dalen JW et al, "Association of Systolic Blood Pressure With Dementia Risk and the Role of Age, U-Shaped Associations, and Mortality." JAMA Internal Medicine, Dec. 13, 2021. DOI: 10.1001/jamainternmed.2021.7009
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