There's no mammogram or Pap smear for Alzheimer's disease. Yet an Alzheimer's group this week begins a push for simple memory screenings in a bid to catch possible warning signs of dementia sooner.

Memory screenings — five-minute mini-tests, doable at a health fair — are hugely controversial. But the provocative new report from the Alzheimer's Foundation of America contends they're a valuable but overlooked tool. The government has begun reviewing if there's enough science to back broader use of them.

How do they work? One example: Tell someone three random words — car, pencil, banana. Then have the person draw a clock with the correct time, as a distraction. A little later, can he or she recall those three words?

Failing such a test doesn't mean someone has dementia. But it signals there might be a problem with short-term memory that should be checked by a doctor. Maybe it's something fixable, like depression or thyroid disease. Maybe it is an Alzheimer's warning sign. Or maybe it's a false alarm and the person just isn't a good test-taker.

Regardless of the uncertainty, there's clearly demand. The Alzheimer's Foundation sponsors a "memory screening day" each November and last month's drew 50,000 takers, 10,000 more than the previous year.

"What we're trying to accomplish is the entry-level 'let's get memory on the radar screen,'" says the foundation's Dr. Richard Powers, medical director of the Alabama Department of Mental Health. "Nobody has a strategy to deal with this."

Indeed, more than 5 million Americans and 26 million people worldwide have Alzheimer's. Cases are projected to skyrocket in the next two decades as the population ages. Yet few are diagnosed in the earliest stages of the relentless brain decay, when today's medications are most helpful.

The new report calls on Congress to set a national strategy for dementia detection, and on Medicare to make memory screening part of more new-patient checkups. Meanwhile, it backs community memory screenings, in particular targeting people who already have memory concerns but don't know how to seek help.

How well do they work? The guideline-setting U.S. Preventive Services Task Force in 2003 decided there wasn't enough evidence to recommend for or against routine screening. The task force is revisiting that question, and other Alzheimer's specialists have urged caution.

Making a check of brain function as routine as blood-pressure measurement is a laudable goal, says Dr. Zaven Khachaturian of the Lou Ruvo Brain Institute in Nevada. But correctly diagnosing people with the earliest symptoms is tremendously difficult, hindering that quest, he says.

Among the knowledge gaps: Nearly a million older Americans each year are estimated to develop what's called "mild cognitive impairment," or MCI. But no one knows how many will worsen to full-blown Alzheimer's, or how to predict who will. To fill such gaps, the government is midway through a giant study to see if brain scans help diagnosis; a Mayo Clinic study of MCI's evolution is tracking 3,000 people in Olmstead County, Minn.; and Khachaturian is planning a similar study to track thousands more Nevada baby boomers.

Plus there's a key distinction: Would memory screening target just people worried about existing problems, or those at risk of future memory loss because of older age, family history or other factors?

Dr. Ronald Petersen of the Mayo Clinic — who advises the Alzheimer's Association, a different national patient-advocacy group — calls wider screening premature.

No matter the cautions, people may assume they're "on the road to Alzheimer's disease," he worries. "If you're in a mall and you go into a booth and you take this little five-minute exercise ... you don't know what people are going to do with that kind of information."

For the truly at-risk, Khachaturian recommends regular monitoring of total cognitive function, not just short-term memory, to spot deterioration from one year to the next.

Screening "needs to be done carefully," he adds. "The danger with willy-nilly doing screening is it opens the door for opportunists."

But the Alzheimer's Foundation's Powers says screening opens the door for consumer education.

On last year's memory screening day, fewer than one in four who confessed to memory concerns said they'd asked a doctor about their problem. Sixteen percent scored poorly enough to have follow-up testing advised; no one knows how many did.

All those others who passed were warned that symptoms could arise later, and given information on steps to protect an aging brain — by, for example, keeping in check the high blood pressure and diabetes that can spur dementia. Alabama officials even created a Web site for such information: http://www.alzbrain.org.

"These are the kinds of dots we need to begin to connect for people," Powers says.

And by the way, what were those three words again?