How Bad Is Hypotension (Low Blood Pressure) for the Brain?

Ask public health officials about HYPERtension and you will be told by the CDC that “Nearly half of adults in the United States (108 million, or 45%) have hypertension defined as a systolic blood pressure ≥ 130 mm Hg or a diastolic blood pressure ≥ 80 mm Hg…” You will also learn that hypertension contributes to roughly half a million deaths each year. HYPOtension (low blood pressure), on the other hand, seems to get far less attention. But low blood pressure can also be dangerous. What can be done about it?

Doctors and Blood Pressure:

Physicians put a lot of effort into treating high blood pressure. That’s because hypertension increases the risk for heart disease, stroke and kidney problems. Some of the most frequently prescribed drugs in the world are blood pressure medicines. Diuretics like hydrochlorothiazide (HCTZ or HTZ) are especially common in many BP combination treatments.

Doctors worry a lot less about low blood pressure. For one thing, hypotension is harder to treat. For another, the long-term negative consequences are less well recognized.

Orthostatic (Postural) Hypotension IS Dangerous!

One form of low blood pressure is postural hypotension, also called orthostatic hypotension. This is what happens when a person stands up and blood pressure falls rapidly. People may experience dizziness or feel faint. Sometimes they fall and suffer an injury (Clinical Interventions in Aging, Jan. 25, 2017).

The official description of this condition published in American Family Physician (Sept. 1, 2011) is:

“Orthostatic hypotension is defined as a decrease in systolic blood pressure of 20 mm Hg [mercury] or a decrease in diastolic blood pressure of 10 mm Hg within three minutes of standing when compared with blood pressure from the sitting or supine position. It results from an inadequate physiologic response to postural changes in blood pressure. Orthostatic hypotension may be acute or chronic, as well as symptomatic or asymptomatic. Common symptoms include dizziness, lightheadedness, blurred vision, weakness, fatigue, nausea, palpitations, and headache. Less common symptoms include syncope [fainting], dyspnea [shortness of breath], chest pain, and neck and shoulder pain.”

Symptoms of Postural Hypotension:

• Dizziness or lightheadedness, especially upon standing
• Feeling faint, disoriented and/or nauseated
• Experiencing brain fog or confusion
• Passing out or falling, especially upon standing suddenly
• Experiencing visual disturbances such as tunnel vision or blurred vision
• Feeling weak and exhausted

What Causes Postural Hypotension?

The action of gravity pulls the blood in the body down into the legs whenever anyone stands up. Compensating mechanisms quickly counteract this effect. There are special sensors that detect a drop in blood pressure immediately, trigger a faster heart rate and constrict blood vessels. These instant adjustments keep most people from feeling lightheaded when they stand up.

Sometimes these mechanisms fail. Certain people are particularly prone to postural hypotension because the heart can’t respond quickly enough. People with a very slow heart rate or those with faulty heart valves may have this unnerving experience frequently.

Dehydration could also make a person more susceptible to orthostatic hypotension, as could conditions like Addison’s disease, diabetes, Parkinson’s disease or thyroid problems. Even advanced age adds to the risk.

A large meal or a few alcoholic beverages may also trigger orthostatic hypotension. Vigorous exercise can have this effect. If you find yourself constipated, straining while sitting on the toilet may paradoxically precipitate an “attack” of low blood pressure.

What To Do if Blood Pressure Goes Too Low:

One reader asked a very simple question. We wish the answer were as straightforward:

Q. Do you have any remedies for low blood pressure?

A. Doctors usually worry far more about high blood pressure, but low blood pressure can cause symptoms such as dizziness, brain fog, fatigue, blurred vision, nausea and fainting. Some people experience these symptoms when they stand up suddenly (orthostatic hypotension).

There is growing recognition of a condition called postural orthostatic tachycardia syndrome (POTS), in which low blood pressure makes the heart race. Doctors are reporting that POTS may be part of a post-COVID syndrome (Immunologic Research, March 30, 2021).

You  can learn lots more about POTS by listening to show 1254 Combating the Long-Term Effects of Post-COVID Syndrome. 

Doctors often recommend non-drug approaches to treat low blood pressure. They include eating more salt, drinking more fluid and wearing compression hose to keep blood from pooling in the legs. In severe cases, physicians may prescribe midodrine (ProAmatine, Orvaten). This drug squeezes blood vessels to raise blood pressure. Patients must not lie down after taking it, as the drug can cause hypertension in such a situation.

Tips from the CDC for dealing with blood pressure that falls too low upon standing:

You will read about too many meds below and how they affect blood pressure.

• Ask your doctor if you can cut back on some meds if you suffer symptoms of postural low blood pressure.
• Get up slowly from bed or from a chair.
• Use a hand rail or support to stand safely
• Get dressed while sitting down
• Avoid walking by yourself if you are dizzy
• Be very careful getting out of the shower or bathtub and keep temperature comfortable but not really hot

Drug-Induced Hypotension:

The cause we worry about most, however, is medication. There are many drugs that can trigger postural hypotension. Ironically, blood pressure pills are near the top of the list. We are especially concerned about older people who are put on three or four different blood pressure medications simultaneously. The more such drugs a person takes the greater the risk of postural low blood pressure. Drugs for mental illness, heart disease, Parkinson’s and erectile dysfunction (ED) can also cause this problem.

Health professionals do not always warn patients about this side effect because it seems less serious than many other adverse drug reactions. But dizziness can lead to a fall and a fracture. When an older person breaks a hip it is often a life-threatening injury. Deaths from falls has gone up dramatically over the last 20 years (Postgraduate Medicine, March, 2015).

Fear of Falling:

Once a person falls, the risk of another such accident goes up significantly. Anyone who has suffered a serious fall is likely to develop a fear of falling. This can have devastating psychological consequences. People may cut back on socializing or physical exercise. They may rely upon a walker or end up in a wheel chair.

Low Blood Pressure and Dementia:

Now a new complication of orthostatic hypotension has emerged. A study of more than 11,000 volunteers that began in 1987 revealed that those with a rapid drop of 20 points of systolic blood pressure when they stood up were 40 percent more likely to develop dementia decades later (American Heart Association Scientific Session, March 10, 2017).

Another large, long-term study was conducted in Sweden (European Journal of Epidemiology, online Feb. 11, 2017).  It tracked more than 18,000 volunteers between 1974 and 2006. People whose diastolic blood pressure dropped upon rising were at increased risk of dementia later in life. The risk rose by 22 percent for every 10 points the pressure dropped.

Seeking the Sweet Spot in Blood Pressure Control:

The moral of this story is that antihypertensive medication may need to be carefully adjusted. Blood pressure should be neither too high nor too low. Finding the sweet spot can be challenging, but the new research suggests it would be worthwhile.

You can learn more about controlling hypertension in our eGuide to Blood Pressure Treatment. This electronic resource can be found in the Health eGuides section of this website. 

Share your own experience with low blood pressure in the comment section below.