NIH Research: A Q&A with Walter J. Koroshetz, M.D., Deputy Director, National Institute of Neurological Disorders and Stroke
Dr. Walter J. Koroshetz is deputy director of the National Institute of Neurological Disorders and Stroke (NINDS). Formerly a professor of neurology at Harvard Medical School, he served as vice chair of neurology service and director of stroke and neurointensive care services at Massachusetts General Hospital. He is a long-standing member of the Brain Attack Coalition (BAC), a group of organizations working to reduce the occurrence of and disabilities and death associated with stroke. Dr. Koroshetz recently talked with NIH MedlinePlus magazine about how people can better protect themselves against stroke and about some of the latest advances in stroke research.
How serious a problem is stroke?
Stroke is very common. It can be devastating. Each year some 750,000 Americans—even young people—suffer injury from stroke. The good news is that a person's annual risk of stroke is down 70 percent since the 1950s and is still declining. But since people are living much longer now, stroke remains a serious problem. As age rises, so does the incidence of stroke. As many as 40 percent of people 80 years or older show signs of "silent" stroke on magnetic resonance imaging (MRI) scans.
What is the major cause of stroke?
High blood pressure—hypertension—is the number one, two, and three cause of stroke! It's the driver of wear and tear on the heart and the blood vessels. There are two types of stroke: hemorrhagic, when a blood vessel bursts in the brain, and ischemic, when a blood vessel in the brain becomes blocked (most often by a clot or hardening of the arteries), reducing blood supply. In both cases, brain tissue dies and functions cease, such as the ability to speak, walk, or think normally.
What can people do about stroke?
People can reduce their risk of stroke. The most important thing is prevention. To keep from having a stroke, work hard on keeping blood pressure normal. Other risk factors to guard against include being overweight, not getting enough exercise, and not eating enough fruits and vegetables. So lose weight, exercise, and maintain a balanced, healthy diet.
For example, a recent study has shown the Mediterranean diet to be extremely effective in reducing the chances of stroke and heart attack. It is high in olive oil, fish, vegetables, fruits, nuts, and whole grains. And very low in red meat and dairy products.
It's the lifestyle changes that go into reducing stroke risk. Stroke can be prevented, but starting when you're 60 may not be soon enough.
Why is it important to get medical help quickly when a stroke is occurring?
The needle moves more rapidly with a stroke than a heart attack. Brain damage occurs very quickly, usually over minutes to hours. So it's a question of whether an intervention can successfully prevent the brain tissue from dying. That is why it is extremely important to get people to the hospital as quickly as possible to begin treatment.
In instances of hemorrhagic strokes, where blood just explodes around the surface of the brain, there has to be emergency treatment to prevent devastating brain damage. For ischemic strokes, drug therapy must begin as soon as possible to dissolve the obstructing clot, return blood flow, and reduce permanent disability. Minutes count!
Where is some of the emphasis these days in prevention and treatment?
In the area of prevention, there is a big push to better understand vascular cognitive impairment—the wear and tear on the small vessels from age and hypertension that cause "silent strokes" and what is called "diffuse white matter disease" in areas of the brain where MRIs show structural changes in up to 80 percent of elderly patients. Both stroke and white matter disease are risk factors for dementia. The more we can understand the basic biology of the aging brain—how blood vessel changes interact with the biology of Alzheimer's disease, for example—the better able we'll be to someday prevent dementia. NINDS and the National Institute on Aging, in particular, are at the center of such research.
On the acute treatment side, tPA (tissue plasminogen activator) remains the only drug approved for the acute treatment of ischemic stroke by the Food and Drug Administration. It is given through a vein. We need to develop newer, safer intravenous drugs, as well as devices that can be inserted into the blocked artery to more quickly and effectively return blood flow to the brain.
Researchers are also looking at ways to slow the time it takes for the brain to die. For example, hypothermia—deep cooling that is known to slow all biologic processes—is a possibility. If we can discover a way to slow the dying process in the brain after stroke, then a great many more people could benefit from treatments that repair the blood vessel.
How about people living with the effects of stroke? Is there anything new for them?
Thankfully, there are now assistive devices, such as self-propelled automated wheelchairs, that permit independent movement. Current research also suggests that thought-controlled robotic arms may someday help patients who have suffered severe strokes. (See "Progress for the Paralyzed") Such devices could be game changers, the result of continuing research to map the brain and interface it with a computer to enable stroke patients to regain function.
How important is the new effort to map the human brain?
The brain is more complex than any computer ever built, its computational energy and power just enormous. We are in the early stages of understanding—of mapping—what the different areas of the brain do and how they work together to enable complex functions, such as speaking or moving your fingers. Often, when one part of the brain dies, another part takes over its function. This is called neuroplasticity. In brain mapping, we are trying to understand how that plasticity happens. That's the key to recovery.