A previously unobserved condition in many Alzheimer's patients that physicians are calling "motion blindness" is a big reason such patients become disoriented and lose their way, asserts a University of Rochester study in the March 23 issue of Neurology.
For years doctors generally have thought that Alzheimer's patients become lost simply because they forget directions or where they're going. But the Rochester team has found that while Alzheimer's patients certainly do have memory problems, those are separate from the motion blindness that is due to brain damage in a highly sophisticated part of the brain that interprets motion.
"People with Alzheimer's get lost not because they can't remember where they've been, but because they can't see where they're going," says lead author Charles Duffy, a neurologist at the University's Strong Memorial Hospital whose team made the finding using computer patterns that look like snowflakes rushing toward the viewer. "Many of these patients are basically blind to the kinds of cues most of us absorb unconsciously every day. It's almost like they're walking around with their eyes closed," says Duffy, associate professor of neurology and ophthalmology and a member of the Center for Visual Science. "It's a disorder of perception as well as memory."
The finding creates the possibility of pinpointing which patients will encounter serious difficulty driving or getting around their neighborhoods, or even their own homes. That would allow some patients to live independently longer than they otherwise might while alerting other families that they should be extra vigilant in keeping tabs on their relatives. It should also spur providers to encourage patients to refer to specific landmarks that are independent of motion when getting around.
The findings are based on experiments in Duffy's Visual
Orientation Laboratory. Patients sit in a chair and watch
computer-generated moving patterns of dots o
Contact: Tom Rickey
University of Rochester