Alzheimer's Epidemic Feared

Sunday, July 9th 2000, 12:00 am

By: News On 6

WASHINGTON (AP) â€” Alzheimer's disease is increasing so fast that more than 22 million people worldwide will be affected by 2025, experts warned Sunday. They urged new research to spot the very earliest symptoms â€” subtle ones that can emerge a decade before true dementia hits â€” and hunt for ways to protect these people's brains.

Already, doctors have discovered that a mild memory impairment sometimes confused with normal aging can progress to full-blown Alzheimer's at a rate of about 12 percent a year.

This ``mild cognitive impairment'' is ``a slippery slope to Alzheimer's,'' Dr. Ronald Petersen of the Mayo Clinic told scientists gathered for the world's largest Alzheimer's meeting. The challenge now, he said, is ``can we predict who will convert more rapidly?''

There is no known cure for Alzheimer's, which today afflicts about 4 million Americans and 8 million others. Scientists do not know what causes the sticky brain deposits that inevitably kill off neural cells until memory disintegrates and ultimately the patient dies.

Lots of risks are under study. Certain genes make some families vulnerable. Head injuries may increase risk; high blood pressure is a new suspect.

People with more education, in contrast, seem at lower risk of Alzheimer's. A study presented Sunday of Swedish twins where one twin had Alzheimer's and the other was healthy suggests a love of reading, as a child and adult, might be protective.

But the biggest risk for Alzheimer's is simply age: Alzheimer's cases double with every five years of age between 65 and 85.

With global population aging, ``We have an imminent worldwide epidemic,'' warned Edward Truschke, president of the Alzheimer's Association. ``If we don't find a cure ... more than 22 million people will have this disease in 25 years.''

Worse, by 2050, 45 million people worldwide may have Alzheimer's, a toll rivaling cancer, said Dr. Robert Katzman of the University of California, San Diego.

``We need to be able to at least delay the onset of Alzheimer's disease,'' Katzman said, because even a treatment that fends off symptoms for a mere five years could halve the disease's burden.

Battling Alzheimer's ``is going to be contingent on identifying symptoms very early, before the disease has gained a foothold in the brain,'' added Dr. Kathleen Welsh-Bohmer of Duke University.

Everybody has occasional memory lapses. Memory loss from early-stage Alzheimer's is far more severe, affecting people's ability to work and causing problems with language or judgment.

Mild cognitive impairment, also called MCI, falls between normal forgetfulness and early Alzheimer's. How to diagnose it is hugely controversial.

But Petersen reported Sunday that people with MCI specifically have trouble with visual memory. Shown a drawing, for example, they are less likely to recall it later than are other people their age.

He said that 12 percent of MCI sufferers progress to full-blown Alzheimer's each year, compared with just 1 percent to 2 percent of normal elderly people who get Alzheimer's each year.

A key factor appears to be the size of the hippocampus, a region of the brain that is important for learning and memory. People with a normal-sized hippocampus, as measured by an MRI machine, seem to decline slowly. People whose hippocampus has started to atrophy at the time of MCI diagnosis decline faster, Petersen said.

``A lot of us think the hippocampus is where the action is in dementia,'' agreed Dr. Yakov Stern of Columbia University.

He traced which brain cells become active during memory tests administered while people lie inside MRI machines, and found that decreased activity in a certain hippocampal region may predict which patients' memory will disintegrate faster.

Five studies involving 4,000 patients around the world are under way to see if early use of Alzheimer's drugs or other substances like vitamin E can prevent, or at least slow, MCI's progression to full Alzheimer's. Results could come as early as 2002, Petersen said.