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New study links 'motion blindness' to Alzheimer's (March 23, 1999 12:49 a.m. EST http://www.nandotimes.com) - A study published Tuesday suggests that people with Alzheimer's disease tend to become lost in familiar surroundings not so much because they're mentally confused but because they are visually impaired. The condition, called "motion blindness," may be the result of isolated damage in one part of the brain, according to the study published in the journal Neurology, scientific journal of the American Academy of Neurology. Scientists at the University of Rochester in New York studied the ability of three different groups of subjects to see and interpret visual patterns - six healthy young people, 12 healthy elderly people, and 11 people with Alzheimer's. In one test, participants viewed a panoramic computer display with radiating patterns of visual motion, simulating what you see as you move through your surroundings. They were then asked whether they seemed to be moving left or right. The Alzheimer's patients had more than twice as much difficulty interpreting the patterns than the other groups. The researchers also tested participants' spatial navigation by walking them from the hospital lobby to the lab, telling them they would be asked questions about the route. The young people answered questions correctly 88 percent of the time and the healthy elderly 72 percent of the time. But the Alzheimer's patients answered correctly only 32 percent of the time. The study counters the generally accepted impression that Alzheimer's is just a memory disorder, the researchers said. "People with Alzheimer's get lost not because they don't remember where they've been, but because they can't see where they're going," said the lead author, Dr. Charles Duffy. "This study gives us a whole new insight into what's going wrong with the brain in Alzheimer's and also gives us a way to measure how debilitated an individual will be by the disease," said Duffy, a neurologist. Visual disorientation is often one of the first symptoms that shows up in Alzheimer's patients and thus could be useful in making an early diagnosis. The tests could also be used to identify those at particular risk for getting lost, Duffy said, such as those who shouldn't be driving due to their visual disorientation. The researchers also suspect that the visual impairment of Alzheimer's patients is so specific that patients may retain other perceptual tools or strategies for finding their way around. Identifying these adjustments might suggest ways to retrain Alzheimer's patients to use other clues to find their way, Duffy said. By LEE BOWMAN Lee Bowman covers health and science for Scripps Howard News Service and can be reached at [log in to unmask] Copyright © 1999 Nando Media Copyright © 1999 Scripps Howard News Service http://www.nandotimes.com/noframes/story/0,2107,30648-49302-362771-0,00.html janet paterson - 52 now /41 dx /37 onset - almonte/ontario/canada <http://www.newcountry.nu/pd/members/janet/index.htm> [log in to unmask]