Boost Your Brain (35 page)

Blood flow blockage in large blood vessels results in “major” strokes, which cause sudden, severe symptoms, such as the loss of feeling on one side of the body or the loss of the ability to speak. Just where in the brain the stroke strikes determines which functions are lost. If the damage occurs in the visual cortex at the back of the brain, for example, a patient may lose vision. If it’s in the motor cortex, toward the middle of the brain, a person may lose the ability to move an arm or leg on one side of the body. In rare cases, the hippocampus or temporal lobes are affected, resulting in acute memory loss and aphasia, or loss of speech. Often stroke affects mood, motivation, personality, and speed of cognitive processing too.

Ischemic strokes can also occur in the small blood vessels in the brain. Instead of killing a large swath of brain tissue, such strokes lead to the death of a small patch of cells about the size of a grain of rice. Such small strokes are often dubbed “silent” strokes because they typically don’t cause obvious symptoms when they occur. But in reality, they are anything but silent; thousands of silent strokes that take place over decades can create thousands of small dead zones. This results in not only slowed thinking but also depression and a lack of energy.

Eventually, strokes of all sizes can add up to marked atrophy in the whole brain, resulting in vascular dementia. In one study, for example, people who’d had strokes were twice as likely to develop dementia later in life.
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In recent years we’ve discovered the existence of yet smaller strokes, so tiny they can only be seen under a microscope. While these are too small to be detected on MRI, they are far from benign. As my friends and colleagues, Johns Hopkins University professors Juan Troncoso and Richard O’Brien, have shown, people who have such microscopic strokes are at a high risk for developing late-life dementia.
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Signs of Stroke

If Marc had experienced chest pains instead of clumsiness in his hand and trouble walking, chances are he would have sought help immediately. People tend to take heart attacks seriously. But many fail to recognize the signs of a stroke. Knowing that, I always tell my patients to think of a stroke as a “brain attack” and treat any sudden neurological symptoms just as seriously as they would if they thought their hearts were in crisis.

Such caution is all the more important because a quick medical response to a stroke can make a huge difference in the outcome. Sufferers of an ischemic stroke who are given the clot-busting drug tPA (tissue plasminogen activator) within three—and possibly as late as four and a half—hours of a stroke, for example, have a far better chance of reducing long-term damage to their brains than those who don’t get treatment.

Often, however, people don’t recognize the symptoms, put off seeking help, or even try to “sleep it off.” Just 3 percent of patients suffering an acute ischemic stroke actually receive a clot-busting drug in time, according to the American Stroke Association. Marc is a perfect example of someone who didn’t seek immediate attention for a stroke.

Since getting quick help can be so beneficial, it’s critical to know the signs of a stroke, and to heed them. They include a sudden onset of:

• numbness or weakness in the face or extremities, especially on one side of the body;

• unexplained confusion;

• difficulty speaking or understanding speech;

• vision loss in one or both eyes;

• difficulty walking;

• dizziness or loss of balance; and/or

• a severe unexplained headache.

The National Stroke Association proposes using the mnemonic FAST for quickly evaluating someone with a suspected stroke:
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F
for
face:
Ask the person to smile. Does one side of the face droop?

A
for
arms:
Ask the person to raise both arms. Does one arm drift downward?

S
for
speech:
Ask the person to repeat a simple phrase. Is the person’s speech slurred or strange?

T
for
time:
Don’t waste time! If you observe any of these signs, call 911 immediately.

Wiping Out Neighborhoods and Highways

When you look at the MRI of a stroke victim the devastation is obvious: those patchy spots dotting the brain represent dead brain cells. You don’t have to be a neurologist to realize the result is a loss of function.

But in addition to the brain cells in grey matter killed by a stroke, limited blood flow can result in damage to white matter. In CogniCity, you can think of it like this: vascular disease can cause a stroke, which decimates the neighborhood, but it can also erode the highways and roads that connect those neighborhoods. Remember, those highways are made of delicate live cells. They need maintenance in the form of a constant supply of oxygen and nutrients.

In the past, many people—even doctors—have dismissed such damage to fiber bundles in the brain as the inevitable result of aging. In fact, radiologists often note it in their reports as “non-specific white matter changes associated with aging.”

But white matter damage isn’t inevitable and it is by no means benign. In recent years we’ve gotten a clearer picture of just how white matter damage affects the brain. In one study, for example, Dr. DeCarli and his colleagues found that white matter damage even in healthy people is associated with lower brain volume and poorer performance on cognitive tests.
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For anatomical reasons, ischemic damage just happens to be more common in the front of the brain than in the back of the brain. Damage that occurs here results in declines in memory, attention, and the ability to perform complex cognitive tasks. Patients with ischemic injury in their frontal lobes may be flummoxed by the “easy check-in” kiosk at the airport or by doing their taxes. “They’re all things that older people get into trouble with,” notes Dr. DeCarli. “And anything that accelerates that then accelerates cognitive aging.”

Some amount of damage in the brain can be overcome, but multiple types of damage are likely to lead to serious irreversible problems. If you have a few small strokes in your frontal lobes, for example, but your temporal lobes are in good shape, you might find that complex mental tasks are challenging but you can still get by in life. But if both your frontal and temporal lobes are damaged, your cognitive decline will almost certainly affect your ability to function independently.

Strokes, meanwhile, can also hamper healthy brain activity. That makes sense since swaths of the brain that die in a stroke don’t function. In fact, in the days before high-tech imaging was widely available, strokes were often detected using EEG, which could easily pick up dead zones. The lack of normal brain activity associated with a stroke explains some of the behavior we see in people with major strokes or extensive damage from silent strokes. Take the example of the stereotypical elderly man whose frontal lobes have been destroyed by a stroke. There’s a reason he’s cranky and erratic: the section of his brain responsible for impulse control has been silenced. If you hooked him up to EEG, you’d find his frontal lobes to be barely buzzing.

Multiple microscopic or silent strokes are associated with brain atrophy as well as damage to the brain’s highways, as are major strokes. The more (or more severe) the strokes, the worse the brain shrinkage.

Warning: Stroke Ahead!

When you consider what’s likely going on in the brain of someone who has had an ischemic stroke it’s no surprise that he or she is at greater risk of a future stroke than someone who hasn’t. It only takes one blocked artery to cause a stroke, but the conditions that led to that blocked artery are almost certain to be having a similar impact in other arteries. This means conditions are likely in place for future strokes, large or small.

In addition, transient ischemic attacks (TIAs)—or ministrokes—are a warning sign of a future stroke. TIAs are caused by the temporary blockage of a blood vessel, which fortunately spontaneously resolves. The symptoms—such as paralysis (usually on one side of the body), loss of balance, or slurred speech—dissipate within one hour and typically cause no lasting damage. Still, a TIA may be a sign of things to come; roughly one-third of people who have TIAs experience a stroke within a year.

Who’s at Risk?

If you’re like Marc, you might have thought you had a few decades more before you had to worry about strokes. But a stroke can strike well before old age, and there’s evidence that strokes may now be affecting young people more than ever before.

A 2012 study published in the journal
Neurology,
for example, showed that the average age of first-time stroke sufferers fell from seventy-one years old in 1993 to sixty-nine in 2005.
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Not only that, but the under-fifty-five age group constituted 19 percent of total stroke sufferers in 2005, compared to just 13 percent in 1993.

For all ages, there are a variety of conditions and behaviors—called vascular risk factors—that affect blood flow in the body and raise the risk of stroke. They include hypertension, diabetes, carotid artery stenosis, peripheral artery disease, atrial fibrillation, coronary heart disease, sickle cell anemia, high cholesterol, inactivity, obesity, and smoking. Heredity may also play a role.

The more risk factors you have, the greater your risk of stroke. If you want a rough idea of your risk, you can use the National Stroke Association’s “Stroke Risk Scorecard.”
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We’re also increasingly learning about other factors that may raise the risk of having a stroke:

Stress and Type A Personality
In one study, researchers found that people who had experienced a major negative life event in the prior six months were nearly four times more likely to suffer a stroke than those who hadn’t.
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For the study, researchers compared 150 middle-age adults in the stroke unit of a hospital with 300 non-stroke sufferers in the same community.

In addition to measuring how much stress study subjects had been under, the research team assessed their behavioral patterns, looking for type A personality traits, such as hostility, aggression, and a quickness to anger. As it turned out, having a type A personality also was linked to stroke, doubling the risk.

Poor Diet
Unhealthy eating that leads to obesity may increase the risk of stroke by virtue of boosting BMI. But high consumption of sodas and a high-sugar, high-salt diet ups your risk of stroke, too. One study, using data from more than 127,000 people who were tracked over more than twenty years, found that having greater than one serving of soda—even diet soda—a day increased the risk of stroke by 16 percent.
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Sleep Disorders
Obstructive sleep apnea and insomnia raise the risk of stroke, as you read in chapter 9. Not only that, but people who have a stroke and obstructive sleep apnea are 76 percent more likely to die following the stroke, compared to those who have a stroke but don’t have sleep apnea.
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Fighting Stroke

The heartbreaking truth about strokes is that once brain cells die, they don’t come back. But even so, the brain has an innate ability to repair itself and so there is tremendous healing activity that takes place after a stroke. Surviving neurons regroup and rewire, with disparate brain areas chipping in, in an effort to compensate for neurons lost to a stroke. Often, stroke sufferers can regain function over time.

I feel passionate about making sure none of my patients experience a stroke. Along with the staff of my brain fitness program, I help patients appreciate the fact that up to 80 percent of strokes can be prevented, and I work with them to understand why and how. Much of the prevention effort comes down to reducing vascular risk factors, such as hypertension, high cholesterol, diabetes, obesity, and a sedentary lifestyle. Doing so may also help reverse some of the damage that is done, even before a large stroke occurs.

At my Brain Center, stroke prevention efforts focus on increasing blood flow to the brain, primarily through improved cardiovascular fitness. Exercise has been shown to aid not only in stroke prevention but also in stroke recovery. In one study, six months of exercise after a stroke resulted in a 50 percent improvement in memory and overall brain function.
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