How high blood pressure affects risk for dementia
September 18, 2019
Alzheimer’s disease and dementia affect nearly 10% of adults in the U.S., and with an aging population, that percentage is likely to increase. While much of the research on dementia has focused on reversing or slowing it down, by the time a patient starts showing symptoms of cognitive decline it may be too late.
Two new studies published recently in the Journal of the American Medical Association (JAMA) hint at a more accessible way to intervene earlier in life to prevent dementia: controlling blood pressure. The first study analyzed records of more than 4,700 people over 24 years and saw that people with hypertension in midlife (ages 44-66) and late-life (ages over 66) had higher risk of developing dementia than those with normal blood pressure. The second showed that lowering blood pressure to a new standard of 120/80 mm Hg (the previous recommendation was 140/90) also reduced the progression of vascular disease in the white matter of the brain, which can be seen by MRI scans.
Shyam Prabhakaran, MD, MS, the chair of the department of neurology at the University of Chicago Medicine, wrote an editorial in JAMA accompanying the two new studies. We spoke to him about how these studies add to a growing body of research that high blood pressure is linked to dementia, and how they hint at a promising new avenue for preventing cognitive decline.
Is this the first time blood pressure has been linked to dementia?
It’s not the first time. There’s a fairly large body of research now going back a decade or two that blood pressure is related to cognitive outcome. This is the first time we’ve seen an intervention to control blood pressure to a goal of 120/80 mm Hg have actual clinical and radiographic benefits to patients. That’s the new finding here, that there are brain health benefits, in addition to heart health benefits, of intensive blood pressure control.
Blood pressure control in midlife is actually a way to prevent dementia. This is a true paradigm shift.
Why is this important for treating dementia?
A lot of research efforts in Alzheimer’s, which is probably the most common dementia, have been unsuccessful because they’re focused on interventions after the disease is detectable clinically, which is too late in most cases. By then the potential research treatments are unlikely to have an effect on the disease progression and outcome.
However, there may a window of opportunity to treat detectable risk factors like high blood pressure well before changes related to dementia begin in the brain. You’re supposed to see your primary care doctor and get your blood pressure measured in midlife. Given the relationship between blood pressure in midlife and dementia in late-life, then you have a fairly recognizable, treatable, modifiable condition that almost anybody could identify and begin treatment for. Arguably, the community health impact of blood pressure control in the general population is much greater than a high-cost, very selective treatment that is not accessible to everybody. Blood pressure treatment theoretically is accessible to everybody. It’s not some novel expensive drug that you must travel to a specialized hospital to receive. If you think about the public health ramifications, it’s really huge.
Every doctor will tell you to keep your blood pressure low for your heart health. Will this add to the argument for controlling your blood pressure now because it could reduce your risk of dementia too?
I would think so. We’ve gotten good at emphasizing heart health. In American society, we’re knowledgeable and we talk about preventing heart attacks. I think brain health is another benefit of blood pressure control. But the blood pressure control that we want to see is stricter than what most practitioners currently advise. It’s not 140/90 mm Hg, which has been the “goal” for most patients in community practice. It would be 120/80 mm Hg, which is a goal that most practitioners haven’t adopted yet.
Should doctors encourage these blood pressure targets for everyone? Or only people who have a family history of dementia?
There’s no downside to shooting for that lower target the first time you’re diagnosed with hypertension. With increased general health screening, people are diagnosed in their 20s or 30s. It’s that long-term exposure people have to recognize as the critical factor, because you’re talking about decades of damage from high blood pressure on your brain and heart. If you don’t intervene until the last 10 years of your life, you can’t reverse everything that went on for 50 years. So, the goal is to change the way we think about the relationship between blood pressure and dementia.
How do you think this will change patient care?
Frankly, there’s still a lot of hypertension that’s untreated or not adequately treated in the community. The most common cause of dementia in our population may be vascular rather than Alzheimer’s, or possibly the two mixed together.
Most dementia treatments have been developed as ways of slowing down disease progression or maybe reversing it after dementia is already diagnosed. Blood pressure control in midlife is actually a way to prevent dementia. This is a true paradigm shift, from thinking about trying to manage dementia after it has already developed to preventing it before its onset.
Shyam Prabhakaran, MD
As a renowned leader in neuroscience research, Dr. Prabhakaran has led projects focused on uncovering the underlying causes of recurrent strokes, improving stroke care, and optimizing patient outcomes and recovery.See Dr. Prabhakaran's bio