RFID transponders used to warn of cognitive decline

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Researchers at the University of South Florida (USF) in Tampa have developed a wireless network that evaluates walking patterns in an attempt to detect early signs of dementia, according to an online article this week in the Massachusetts Institute of Technology's Technology Review.

"We're looking at a device that may help us perform early detection [of dementia] as a way of ensuring that [older] people get the best remaining years they can," said William Kearns, an assistant professor, who researches aging and mental health at USF. In particular, dementia increases the risk of injury caused by a fall. "That's a huge problem for assisted-living facilities."

To test the approach, the USF researchers put RFID tags on the wrists of residents at two assisted-living homes in Florida. These tags transmitted signals that were picked up by receivers placed around each building, revealing the wearer's movements in all three spatial dimensions to within 10 inches of accuracy.

The researchers analyzed participants' movements for telltale signs of cognitive decline: a tendency to wander, veer suddenly, or repeatedly pause. In one of the studies involving 20 residents, the researchers found a statistical relationship between those who showed abnormal walking patterns and those whose mental test scores indicated dementia.

In the future, the USF team plans to develop software that will automatically detect these warning signs.

The USF approach relies on RFID equipment. The ultra-wideband (UWB) chips used suffer less interference than do passive RFID chips and can send and receive signals through walls. The transmitters have a range of 600 feet and allow multiple people to be monitored even in a crowded room. The tags have batteries that last up to three years and accelerometers that put them into sleep mode when the user is motionless. According to Kearns, the entire system, including half a dozen tags, costs around $7,000 to implement.

Although walking patterns have been tied to dementia in previous studies, some experts question the approach.

"There are a lot of factors that influence movement, and the disease in its very early stages is not a movement disease," said Robert Green, co-director of the Alzheimer's Disease Clinical and Research Program at Boston University. Green also pointed out that the USF researchers only looked for post-symptomatic dementia in their test.