Alzheimer's disease and its associated dementia can be a scary prospect for individuals and families faced with it. Between 2.4 million and 4.5 million Americans suffer from this debilitating, incurable disease, according to the National Institutes of Health. That figure is expected to rise as the baby boomers age.

Community memory screening events are becoming increasingly popular as individuals and their families seek to detect dementia in its earliest stages—before it destroys patients' memories and thinking skills. But many physicians warn against these screenings, which are often ineffective when it comes to detecting dementia, and can leave test-takers feeling scared and powerless.

There are thousands of memory screening tests available, some self-administered online, some given in the community by health care professionals—usually in the form of a questionnaire. The Alzheimer's Foundation of America, the advocacy group that funds National Memory Screening Day, promotes screenings overseen by health care professionals only.

"If someone goes online and does a self test, even if there are two pages of explanation of the results, I'm not sure that people understand what they are reading," says Eric Hall, the foundation's president and founder.

Hall says a health care professional can explain what a negative result on a memory test means and educate the individual and family members on what type of questions to ask the doctor. Most importantly, Hall says, a health care professional is there to emphasize that a negative result on a memory test is not an Alzheimer's disease diagnosis but simply means the individual should to go to a doctor for follow-up tests.

On the other hand, the U.S. Preventive Services Task Force (USPSTF), an independent panel of government experts that assesses the effectiveness of clinical services, such as memory screenings, has found insufficient evidence to support routine dementia testing in older adults. According to the USPSTF, screenings are only sometimes effective when it comes to detecting the cognitive impairment associated with dementia. And because treatment for Alzheimer's is limited, the task force found no evidence that the quality of life benefits of catching it early with memory screening outweigh the psychological stress of being labeled with an incurable disease.

"We should not screen for a disease we cannot effectively treat. If we could prevent Alzheimer's disease then it would be very important for us to identify people in the earliest stages," says Charles DeCarli, head of the Alzheimer's Disease Center at the University of California, Davis. DeCarli does not screen for dementia, but says he would if there was a therapy that could cure or effectively manage the disease.

Along with the logic of dementia screening, DeCarli and other physicians question the efficacy of memory screening tests themselves. For every seven people that come to DeCarli's office after failing a memory-screening test, only one is diagnosed with dementia. "There are many reasons to fail a screening test," he says. "The person may be nervous, or they could be on a medication that impairs their memory."

Memory screening tests are not good indicators of dementia because they offer only a snapshot of someone's mental abilities, says John Morris, director of the Alzheimer's Disease Research Center at the Washington University in St. Louis School of Medicine. Dementia is characterized by a change in a person's cognitive abilities over time. "If you go to a community center and take a memory test, it doesn't say whether you would have scored better or the same a year ago. Screening doesn't tell us if people are changing," Morris says.

Memory tests may also be limited in terms of detecting dementia in ethnic minorities, says Jed Levine, executive vice president of the Alzheimer's Association–New York City Chapter, an advocacy group. For individuals who speak English as a second language, not understanding some of the words on a questionnaire or not understanding the instructions may lead to a failed test even if there is no problem with the person's mind.

So what should you do if you've noticed a decline in your own memory or the cognitive abilities of a relative or friend? Seek a physician who has experience diagnosing dementia and who works with dementia patients—your primary care doctor, a geriatrician, geriatric psychologist or a neurologist, Miller says.

When assessing a patient for dementia, the physician will run a battery of tests—from questionnaires to brain scans. Most importantly, Miller notes, the physician will sit down with someone who knows the patient well—usually a spouse, adult, child or neighbor—and interview them about any changes that have taken place in the patient's memory that are beginning to interfere with daily life. Most often, people with dementia are unaware that they are changing, according to Miller, who says that a close relation can usually give the best indication of changes in a person's ability to remember things over time.

Failing a memory screening test, on the other hand, makes people scared about a disease they may but probably do not have, DeCarli says—and without a full physician's assessment, there is no reliable way of knowing whether someone has Alzheimer's or not.

This article is provided by Scienceline, a project of New York University's Science, Health and Environmental Reporting Program.