A New Way to Predict Alzheimer's? (And Ways to Ward Off Memory Loss)

A section of the brain on an MRI scan.

Video: Signs of Alzheimer's

If Alzheimer's disease runs in your family, you've probably given some thought to whether you can escape. A new study provides some insight, scoring 3,375 older people on a list of factors that researchers found predicted the risk of developing dementia. Deborah Barnes, lead author and assistant professor of psychiatry at the University of California-San Francisco, says that she hopes the system can one day be boiled down into a shorter checklist that can be completed in five to 10 minutes in a doctor's office. By filtering out some of the more expensive predictors—those involving brain MRIs, for instance—Barnes says she hopes to see an easy, inexpensive index developed one day.

The people studied earned 1 or 2 points for each measure that applies to them, resulting in a score of zero to 15. In the study, 56 percent of people who earned a high score on the index—defined as 8 or more points—developed dementia within six years. Twenty-three percent of those who had moderate scores—4 to 7 points—developed dementia within that time. And 4 percent of those who had low scores—3 or fewer points—ended up with dementia within six years. Since the risk factors are predictive of dementia but are not necessarily causal, Barnes notes, "changing these things would not necessarily mean that you would lower your risk of dementia."

In case you want to take precautions, here's a look at the items that make up the index and some steps you can take now to improve your score later in life:

• How old you are can predict whether you're at risk for dementia. Those who are between the ages of 75 and 79 get 1 point on the index, and those ages 80 to 100 get 2 points. "It's really clearly established that age is the most important risk factor for developing dementia," says Barnes. "The older you are, the higher your risk for developing dementia.
• Researchers used two measures of cognitive function—a standard measure of global cognitive function and performance on a timed test of attention. A low score on either of the tests results in 2 points per test. Try these tips for keeping your brain agile and your thinking and memory sharp.
• A body mass index less than 18.5 is worth 2 points on the index. A person who is 5 feet, 7 inches tall and weighs less than 115 pounds would fit into this category, for instance, as would someone who is 6 feet tall and weighs less than 135 pounds, Barnes says. In contrast, some studies have found that in midlife, being overweight is associated with an increased risk of dementia and other health problems.
• "BMI tends to decline about 10 years before onset of dementia," Barnes says. In very late life, she says, "you should be more worried about being underweight than being overweight." A tip: One way to increase BMI without eating more is to build up muscle mass. It's not a guarantee that it will protect against dementia, "but it probably won't be a bad thing," Barnes says. Learn how to avoid losing muscle mass as you age.
• A person who possesses a genetic risk factor called apolipoprotein E e4 allele gets 1 point on the index. But people are not routinely tested for this risk factor because it's not believed to be 100 percent predictive of who will develop dementia, Barnes says. Some experts "feel that testing people would alarm them unnecessarily," she says, though it's possible to ask a doctor to be tested for it.
• Irregularities observed on brain MRIs also factor into the score. White matter disease—involving fibers of the brain that connect neurons together—is thought to be a marker of the impact of vascular disease. People with a certain level of this type of disease get 1 point on the index. To try to ward off white matter disease, focus on lowering your risk of diabetes and hypertension, Barnes advises. That means eating right and staying fit. If you do develop one or both conditions, it's important to keep them well controlled by following your doctor's instructions, Barnes says. Enlarged ventricles of the brain, also observed via MRI, earn 1 point on the index. When ventricles are enlarged, "it means you have more open space and less tissue," Barnes says. "It's just a shrinkage of the brain."
• Internal carotid artery thickness can be measured using an ultrasound. If the artery wall is greater than or equal to 2.2 millimeters in thickness, you get 1 point on the dementia index. Diet and exercise are key here, too, in an effort to ward off vascular disease that can lead to this problem, Barnes says.
• Those who've had coronary bypass surgery also earn 1 point on the index. Obviously, "if somebody needs that kind of surgery, they should get it," Barnes says. But it's best to prevent heart problems from developing in the first place by maintaining a healthful diet and exercise, she advises.
• Researchers also measured the time it took for study subjects to put on and button a shirt. Those who took longer than 45 seconds earned 1 point on the index. "Several other studies have found that timed performance measures seem to be predictive of dementia risk," Barnes says. This particular test was a timed measure of fine motor function. One study showed that an electrical zap to the brain may help improve motor skills.
• Abstaining from alcohol was also considered to be predictive of dementia, resulting in 1 point on the index. But Barnes warns that drinking alcohol regularly does not mean you'll protect yourself. If someone is already drinking moderately, fine, she says. But don't start drinking because of the study.