LONDON, Jul 19, 2001 (United Press International via COMTEX) -- Scientists in England have used magnetic resonance imaging and a unique mapping technique to study subtle changes in the brains of Alzheimer's patients months before any outward behavioral symptoms appear.

In a special early report from the July 20 edition of The Lancet medical journal, released Thursday, the researchers found the technique accurately diagnosed Alzheimer's in four patients before the onset of clinical symptoms. Each of the patients carried a genetic mutation making them strongly predisposed to the disease.

"Early diagnosis and monitoring of the progression of Alzheimer's disease is vital if we are to develop therapeutic strategies to prevent the disease," Dr. Nick Fox, a member of the study team, told United Press International. "We were able to diagnose with 100 percent accuracy the disease in these patients before they had any symptoms."

Fox and Dr. Martin Rossor, from the National Hospital in London, used an imaging technique called voxel-compression mapping to view degeneration of brain cells in the four patients.

The patients, from families with a history of early onset Alzheimer's disease, underwent MRI periodically over five to eight years and all four developed symptomatic Alzheimer's disease during follow-up. Twenty individuals with a clinical diagnosis of probable Alzheimer's and 20 control participants also underwent serial MRI.

To date, there is no way to make a physical diagnosis of Alzheimer's. Patients begin to exhibit characteristic signs of the disease, such as memory loss and dementia, but only by examining the brain after death can doctors be sure. Alzheimer's victims have characteristic brain damage caused by plaques.

"We hope that this method will help with improving earlier diagnosis," Fox said. "Our study adds to the evidence the effects of the disease on the brain are detectable earlier than we previously realized. Perhaps more importantly, we hope that these techniques may also help identify those treatments which are actually going to slow this devastating disease."

Fox said the research team was able to show a pre-symptomatic phase lasting three years or more that includes increased rates of tissue loss.

"It raises the hope that we might one day be able to intervene with therapy at a very early stage," he said.

Last July, researchers in San Francisco announced they had successfully used magnetic resonance spectroscopy to detect the death of brain cells in Alzheimer's patients by measuring the levels of certain chemical markers. Using the imaging technique, they were able to differentiate between Alzheimer's patients and healthy people, and between Alzheimer's and vascular dementia, a disease with similar symptoms.

Norbert Schuff, a radiologist specializing in Alzheimer's imaging at the San Francisco Veteran's Affairs Medical Center, told UPI the new study adds to the hope doctors may soon have ways to identify the disease at its earliest onset.

"It can be eye-opening to see the deterioration that sets in," said Schuff, who has been involved in the development of MRI and MRS for more than 10 years.

"We deal with adults -- accomplished people, former teachers and so on -- who, in some cases, have become totally helpless," he said. "You have to explain how to lie down, how to close your eyes, what it means to close your eyes. If you're not confronted with this daily, it's hard to understand. Now, we may not be able to help these particular people, but we have to continue to work to provide hope for future generations."

Schuff believes that brain-imaging techniques like MRI and MRS offer hope for improved early detection of Alzheimer's disease without significant investment in new equipment.

"So many people are already getting MRIs as part of the normal process for other diseases, like brain tumors," Schuff said. "What we are doing is moving toward the day when we will be able to measure the rate of change and metabolism in the brain to improve diagnosis of Alzheimer's."

An estimated 4 million people suffer from varying degrees of Alzheimer's in the United States and that number is expected to jump to 7 million when the baby boom generation reaches age 65, according to the Alzheimer's Association. By the middle of the next century, some 14 million could be affected.

There is no medical treatment currently available to cure or stop the progression of Alzheimer's disease, however four FDA approved drugs -- tacrine, donepezil, rivastigmine and galantamine -- may temporarily relieve some symptoms of the disease.

Reported by UPI Medical Writer Kurt Samson, in Washington