June 10 (Bloomberg) -- The number of people living with Alzheimer's disease probably will quadruple by 2050, and delaying the onset of the condition even by one year might reduce the effect by more than 10 percent, scientists said.

More than 106 million people worldwide will have the condition by 2050, based on factors such as an aging population, researchers wrote in a study released today. The greatest increase will occur in Asia, which will account for 59 percent of all cases then, compared with 48 percent now.

One in 85 people would have the disease at current rates, and 43 percent of cases will be so advanced that they'll require nursing-home care, the researchers said. Alzheimer's disease is incurable and the top cause of dementia among the elderly, according to the National Institutes of Health in Bethesda, Maryland. Care for patients can be expensive, with specialized facilities costing about $5,000 a month.

``The point is that we don't have to hit the home run,'' said Ron Brookmeyer, the lead author of the study and a biostatistician at the Johns Hopkins Bloomberg School of Public Health in Baltimore. ``It would be great if we could, but even just delaying the disease modestly could have a big impact.''

Postponing the onset of Alzheimer's by a year could reduce the number of people with the disease by 12 million by 2050, the researchers said in the study, to be published in July issue of the journal Alzheimer's and Dementia.

Alzheimer's usually is diagnosed after the age of 60, and the likelihood of having the disease doubles every five years after the age of 80, Brookmeyer said in a June 7 telephone interview.

Early Diagnosis

The study shows the need for early diagnosis and greater awareness among everyone from health-care providers to bank tellers, said Nancy Stiles, a senior researcher at the University of Kentucky's Alzheimer's Disease Research Center in Lexington. Half to three-fourths of people with mild to moderate dementia are undiagnosed, she said.

``The symptoms can be so subtle that trying to identify it in a clinic room is very different from the approach we use for other diseases,'' said Stiles, who wasn't affiliated with the study, in a June 8 interview.

Other people in the community also could help identify those beginning to experience mild memory loss, she said.

``Bank tellers pick this up very well because they see someone dealing with a complex situation: did they fill the check out right?'' Stiles said.

Alzheimer's begins with memory problems and ends with severe brain damage. The first symptom may be only mild forgetfulness, which can be confused with age-related memory changes, the National Institute on Aging says.

Routine Tasks

As Alzheimer's progresses, it can interfere with routine tasks as patients forget how to brush their teeth, for example, or put on their clothes, or they cease to recognize familiar places and people. Eventually, patients need around-the-clock attention. Most live five to 10 years after the initial diagnosis.

Regular exercise, both mental and physical, can minimize the effects of the disease, Stiles said. Continuing to pursue challenging mental tasks also seems to slow disease progression. Staying physically fit lessens the likelihood of complications, like stroke, that are especially severe in patients with Alzheimer's.

The study was funded by Elan Corp. and Wyeth, which said in May they would start the last stage of trials usually required for a drug's approval for their experimental compound known as Bapineuzumab, for Alzheimer's disease. Should the drug be approved, peak revenue from Bapineuzumab may reach $5 billion based on a price of $25,000 per patient a year, according to analyst Catherine Arnold of Credit Suisse.

Marketed Drugs

Drugs sold for slowing progression of the disease and treating symptoms include Johnson & Johnson's Razadyne, Novartis AG's Exelon, and Forest Laboratories Inc.'s Namenda, according to that National Institutes of Health.

Brookmeyer and his team created a model using population data from the United Nations and studies of the prevalence of the disease. The research is sensitive to a number of variables, including increasing lifespan, Brookmeyer said.

``Even when we modified the assumptions of mortality rates, the proportionate increase in the burden of disease didn't change,'' Brookmeyer said. ``People may quibble with the exact numbers, but I'm confident that whatever number we use, there will be a quadrupling.''

New York Mayor Michael Bloomberg, founder and majority owner of Bloomberg News parent Bloomberg LP, is an alumnus and benefactor of Johns Hopkins University, in whose honor the Bloomberg School of Public Health is named.

To contact the reporter on this story: Elizabeth Lopatto in New York at elopatto@bloomberg.net

Last Updated: June 10, 2007 00:27 EDT