Imagine living into your 80s and thinking as clearly as ever, dodging the grasp of dementia (search), Alzheimer’s (search) disease, or milder brain problems like memory loss.

Alzheimer’s disease and dementia eventually claim many senior minds, but some people never seem to fall prey to those conditions. You may know someone like that. Perhaps you’ve had a relative whose mind stayed sharp as a tack well into old age.

What’s their secret? It’s a timely question, and not just for scientists. Baby boomers are watching their parents get older -- and spotting a few grey hairs of their own in the mirror. What can they expect from the aging brain?

A new study hints at what may be to come. The results are a mix of good and bad news, with a tantalizing hint about mental staying power.

Some studies have suggested that subtle memory problems can progress to Alzheimer's disease or other forms of dementia. This may mean that people with mild memory problems might be at risk for Alzheimer's or that mild memory problems may be a very early form of Alzheimer's disease.

The new study says that "memory loss is not an inevitable consequence of aging, but rather is usually the consequence of age-related diseases."

Inching Toward Alzheimer’s Disease?

First, the bad news. Out of 180 study participants who died in their 80s, autopsies showed that nearly all had some brain changes typical of Alzheimer’s disease.

Soon before dying, 83 participants had dementia, 37 had mild cognitive impairment (search) (MCI), and 60 did not have memory problems.

MCI means a person has memory problems greater than average for his or her age. According to the Alzheimer's Association, the person with mild cognitive impairment does not have other signs of dementia like problems with judgment or reasoning.

What’s more, mild memory problems seemed to indicate that patients were heading toward more serious brain problems typically seen in old age, such as Alzheimer’s disease and dementia.

“From a clinical standpoint, even mild loss of cognitive function in older people should not be viewed as normal, but as an indication of a disease process,” says David Bennett, MD, in a news release. Bennett worked on the study and directs the Rush Alzheimer’s Disease Center at Rush University.

The subjects were not typical Americans. Instead, they were Catholic clergy enrolled in a long-term study of aging and dementia. They took mental tests every year since 1993. After they died, the researchers measured how much disease their brain showed, looking at signs similar in appearance to Alzheimer's brains.

The study appears in the March 8 edition of the journal Neurology.

Beating the Odds

Now, the good news. A third of the study’s subjects had no memory problems, even though the physical signs of Alzheimer’s disease were quietly gathering in their brains.

Those people may have had some sort of safeguard that kept dementia at arm’s length. Perhaps they had a bigger “neural reserve” that let them withstand brain changes, write the researchers. Their mental powers might have eventually faded, but yearly tests showed clear thinking until death, says the study.

Take-Home Message

Why were some participants unaffected by brain changes? If they had a protective nerve tissue “reserve,” what is it, and how can other people get it?

Those questions are sure to be studied further. Meanwhile, it might be a good idea to pay attention to older people’s small mental slipups.

Those glitches might be nothing -- we all have our bad moments -- or they might be a first sign of trouble. Though Alzheimer’s disease has no cure, early warning can give families more time to prepare. If you’re concerned, ask your doctor for testing or advice.

Evidence of memory loss among people of any age should be taken seriously by individuals, family members, and health care providers alike, say the researchers.

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: Bennett, D. Neurology, March 8, 2005; vol 64: pp 834-841. News release, American Academy of Neurology.