NATIONAL INSTITUTES OF HEALTH NIH News
National Institute of Neurological Disorders and Stroke (NINDS)

 

Embargoed for Release: Monday, November 7, 2011, 4 p.m. EST

 

NIH STUDY FINDS STROKE RISK FACTORS MAY LEAD TO COGNITIVE PROBLEMS

 

Stroke is a medical emergency and the third leading cause of death in the U.S. It occurs when a blood vessel in the brain bursts or, more commonly, when a blockage develops. Without treatment, cells in the brain quickly begin to die. The result can be serious disability or death. If a loved one is having stroke symptoms, seek emergency medical attention without delay.

 

High blood pressure and other known risk factors for stroke also increase the risk of developing cognitive problems, even among people who have never had a stroke, a study funded by the National Institutes of Health has found.

 

“Our results emphasize the importance of early intervention to treat high blood pressure and preserve cognitive health prior to a stroke or other cerebral event,” said first author Frederick Unverzagt, Ph.D., a professor of psychiatry at Indiana University School of Medicine in Indianapolis.  The study appears in the Nov. 8, 2011 issue of Neurology.

 

The new findings come from the REasons for Geographic and Racial Differences in Stroke (REGARDS) study, an effort to track stroke risk and cognitive health in an ethnically and demographically diverse sample of the U.S. population 45 and older.  Since 2003, the study has followed more than 30,000 people.  The study is funded by NIH’s National Institute of Neurological Disorders and Stroke (NINDS) and is led by George Howard, Ph.D., chair of the biostatistics department at the University of Alabama at Birmingham.

 

Strokes, which affect some 795,000 Americans each year, occur when blood vessels that supply the brain rupture or become blocked.  A stroke can cause a host of cognitive disabilities, including effects on memory, speech and language, and everyday problem solving.  But even without suffering a stroke, individuals at risk for stroke may experience cognitive problems as their blood vessels deteriorate.

 

For this analysis, the REGARDS team collected data on nearly 24,000 study participants who had no history of cognitive impairment or stroke, and no evidence of stroke during the study.  At the start, the researchers assessed each person’s stroke risk with the Framingham Stroke Risk Profile, which incorporates risk factors including age, high blood pressure, diabetes and heart problems.  They also assessed cognitive health with a six-item screening test that required participants to give the year, month and day, and to remember three items from a list after a short delay.  The test was repeated annually, and the average follow-up time was 4.1 years.

 

“A strength of this study is that it looked at people who were cognitively healthy at the start and reassessed their cognitive function periodically to see who developed problems over time,” said NINDS Deputy Director Walter Koroshetz, M.D.  “This allowed the investigators to explore whether certain risk factors were predictive of, rather than just correlated with, cognitive impairment.”

 

Over the course of the study, 1,907 people without an evident stroke showed cognitive impairment, which was significantly associated with their baseline Framingham score.  In this group, age and left ventricular hypertrophy (LVH), an enlargement of the heart, were the only score components that independently predicted cognitive decline.  Similar to the risk of stroke, each 10-year increment in age doubled the risk of cognitive impairment.  LVH, when adjusted for other factors, increased the risk by about 30 percent.

 

Since LVH can result from high blood pressure, the researchers did a separate analysis excluding people with LVH.  In this smaller group, high blood pressure was an independent predictor of cognitive decline, with each 10 mm Hg increase in systolic blood pressure bumping up the risk by 4 percent.

 

Consistent with a prior report from REGARDS (http://www.ninds.nih.gov/news_and_events/news_articles/cognitive_decline_stroke_belt.htm), demographic risk factors for stroke were also risk factors for cognitive decline.  Men, African-Americans of both sexes, and residents of the Stroke Belt (Alabama, Arkansas, Georgia, Louisiana, Mississippi, North Carolina, South Carolina and Tennessee) had a higher risk of cognitive decline.  Education was also a factor, with the risk of cognitive decline decreasing as education increased.

 

The people who experienced cognitive decline may have had silent strokes or other subclinical changes affecting the brain’s blood supply, Dr. Unverzagt said.  The study does not rule out other possible causes, such as Alzheimer’s disease, but Dr. Unverzagt notes there is growing recognition of an overlap between the pathology of stroke and Alzheimer’s.  The two conditions share several risk factors – including high blood pressure.

 

NINDS (www.ninds.nih.gov) is the nation’s leading funder of research on the brain and nervous system.  The NINDS mission is to reduce the burden of neurological disease — a burden borne by every age group, by every segment of society, by people all over the world.

 

About the National Institutes of Health (NIH): NIH, the nation’s medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit <www.nih.gov>.

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REFERENCE:  Unverzagt FW et al.  “Vascular Risk Factors and Cognitive Impairment in a Stroke-free Cohort.”  Neurology, November 8, 2011, Vol. 77 (19), p. 1729.

 

 

Stroke Symptoms

Signs of a stroke may include:

  • Sudden numbness or weakness of the body, especially on one side.
  • Sudden vision changes in one or both eyes, or difficulty swallowing.
  • Sudden, severe headache with unknown cause.
  • Sudden problems with dizziness, walking, or balance.
  • Sudden confusion, difficulty speaking or understanding others.

Call 911 immediately if you notice any of these symptoms.

 

Stroke Test: Talk, Wave, Smile

The F.A.S.T. test helps spot symptoms. It stands for:
Face. Ask for a smile. Does one side droop?
Arms. When raised, does one side drift down?
Speech. Can the person repeat a simple sentence? Does he or she have trouble or slur words?
Time. Time is critical. Call 911 immediately if any symptoms are present.

 

Stroke: Time = Brain Damage

Every second counts when seeking treatment for a stroke. When deprived of oxygen, brain cells begin dying within minutes. There are clot-busting drugs that can curb brain damage, but they have to be used within three hours of the initial stroke symptoms. Once brain tissue has died, the body parts controlled by that area won’t work properly. This is why stroke is a top cause of long-term disability.

Diagnosing a Stroke

When someone with stroke symptoms arrives in the ER, the first step is to determine which type of stroke is occurring. There are two main types, and they are not treated the same way. A CT scan can help doctors determine whether the symptoms are coming from a blocked blood vessel or a bleeding one. Additional tests may also be used to find the location of a blood clot or bleeding within the brain.

 

Diagnosing Stroke

 

When someone with stroke symptoms arrives in the ER, the first step is to determine which type of stroke is occurring. There are two main types, and they are not treated the same way. A CT scan can help doctors determine whether the symptoms are coming from a blocked blood vessel or a bleeding one. Additional tests may also be used to find the location of a blood clot or bleeding within the brain.

 

Ischemic Stroke

The most common type of stroke is known as an ischemic stroke. Nearly nine out of 10 strokes fall into this category. The culprit is a blood clot that obstructs a blood vessel inside the brain. The clot may develop on the spot or travel through the blood from elsewhere in the body.

 

Hemorrhagic Stroke

Hemorrhagic strokes are less common but far more likely to be fatal. They occur when a weakened blood vessel in the brain bursts. The result is bleeding inside the brain that can be difficult to stop.

 

‘Mini-Stroke’ (TIA)

A transient ischemic attack, often called a “mini-stroke,” is more like a close call. Blood flow is temporarily impaired to part of the brain, causing symptoms similar to an actual stroke. When the blood flows again, the symptoms disappear. A TIA is a warning sign that a stroke may happen soon. It’s critical to see your doctor if you think you’ve had a TIA. There are therapies to reduce the risk of stroke.

 

What Causes a Stroke

A common cause of stroke is atherosclerosis — hardening of the arteries. Plaque made of fat, cholesterol, calcium, and other substances builds up in the arteries, leaving less space for blood to flow. A blood clot may lodge in this narrow space and cause an ischemic stroke. Atherosclerosis also makes it easier for a clot to form. Hemorrhagic strokes often result from uncontrolled high blood pressure that causes a weakened artery to burst.

 

Risk Factors: Chronic Conditions

Certain chronic conditions increase your risk of stroke. These include:

  • High blood pressure
  • High cholesterol
  • Diabetes
  • Obesity

Taking steps to control these conditions may reduce your risk.

 

Risk Factors: Behaviors

Certain behaviors also increase the risk of stroke:

  • Smoking
  • Getting too little exercise

Heavy use of alcohol

 

Risk Factors: Diet

A poor diet may increase the risk for stroke in a few significant ways. Eating too much fat and cholesterol can lead to arteries that are narrowed by plaque. Too much salt may contribute to high blood pressure. And too many calories can lead to obesity. A diet high in fruits, vegetables, whole grains, and fish may help lower stroke risk.

 

Risk Factors You Can’t Control

Some stroke risk factors are beyond your control, such as getting older or having a family history of strokes. Gender plays a role, too, with men being more likely to have a stroke. However, more stroke deaths occur in women. Finally, race is an important risk factor. African-Americans, Native Americans, and Alaskan Natives are at greater risk compared to people of other ethnicities.

 

Stroke: Emergency Treatment

For an ischemic stroke, emergency treatment focuses on medicine to restore blood flow. A clot-busting medication is highly effective at dissolving clots and minimizing long-term damage, but it must be given within three hours of the onset of symptoms. Hemorrhagic strokes are more difficult to manage. Treatment usually involves attempting to control high blood pressure, bleeding, and brain swelling.

 

Stroke: Long-Term Damage

Whether a stroke causes long-term damage depends on its severity and how quickly treatment stabilizes the brain. The type of damage depends on where in the brain the stroke occurs. Common problems after a stroke include numbness in the arms or legs, difficulty walking, vision problems, trouble swallowing, and problems with speech and comprehension. These problems can be permanent, but many people regain most of their abilities.

 

Stroke Rehab: Speech Therapy

Rehabilitation is the centerpiece of the stroke recovery process. It helps patients regain lost skills and learn to compensate for damage that can’t be undone. The goal is to help restore as much independence as possible. For people who have trouble speaking, speech and language therapy is essential. A speech therapist can also help patients who have trouble swallowing.

 

Stroke Rehab: Physical Therapy

Muscle weakness, as well as balance problems, are very common after a stroke. This can interfere with walking and other daily activities. Physical therapy is an effective way to regain strength, balance, and coordination. For fine motor skills, such as using a knife and fork, writing, and buttoning a shirt, occupational therapy can help.

 

Stroke Rehab: Talk Therapy

It’s common for stroke survivors and their loved ones to experience a wide range of intense emotions, such as fear, anger, worry, and grief. A psychologist or mental health counselor can provide strategies for coping with these emotions. A therapist can also watch for signs of depression, which frequently strikes people who are recovering from a stroke.

 

Stroke Prevention: Lifestyle

People who have had a stroke or TIA can take steps to prevent a recurrence:

  • Quit smoking.
  • Exercise and maintain a healthy weight.
  • Limit alcohol and salt intake.
  • Eat a healthier diet with more veggies, fish, and whole grains.

Stroke Prevention: Medications

For people with a high risk of stroke, doctors often recommend medications to lower this risk. Anti-platelet medicines, including aspirin, keep platelets in the blood from sticking together and forming clots. Anti-clotting drugs, such as warfarin, may be needed to help ward off stroke in some patients. Finally, if you have high blood pressure, your doctor will prescribe medication to lower it.

 

Stroke Prevention: Surgery

In some cases, a stroke results from a narrowed carotid artery — the blood vessels that travel up each side of the neck to bring blood to the brain. People who have had a mild stroke or TIA due to this problem may benefit from surgery known as carotid endarterectomy. This procedure removes plaque from the lining of the carotid arteries and can prevent additional strokes.

 

Stroke Prevention: Balloon and Stent

Doctors can also treat a clogged carotid artery without major surgery in some cases. The procedure, called angioplasty, involves temporarily inserting a catheter into the artery and inflating a tiny balloon to widen the area that is narrowed by plaque. A metal tube, called a stent, can be inserted and left in place to keep the artery open.

 

Life After a Stroke

More than half of people who have a stroke regain the ability to take care of themselves. Those who get clot-busting drugs soon enough may recover completely. And those who experience disability can often learn to function independently through therapy. While the risk of a second stroke is higher at first, this risk drops off over time.