MADRID, Spain (AP) - The death of an Alzheimer's patient who strayed from home and tumbled down a hillside has prompted an ambitious project to use satellites to find wandering victims of the brain-wasting disease.

The idea, developed by a Spanish Alzheimer's association and due to be introduced late this year, is to have patients wear a tracer that would activate if the user goes beyond a set radius from home.

The device would emit a signal that bounces off a satellite and into a monitoring center where staff would call relatives and determine if the patient is in fact missing. If so, police are given real-time coordinates mapped by the satellite and sent out to find the patient.

No such device is currently available in Europe or anywhere else, according to experts on Alzheimer's disease, a degenerative brain disorder that robs people of their memories and sometimes of their minds. At least two companies are working on the idea.

It originated three years ago when a Spaniard with Alzheimer's strayed from his home in Barcelona and was found dead months later on the other side of town on the slopes Montjuic, a city landmark.

Then, in November of last year, another Alzheimer's patient vanished from his home in the southwestern city of Almeria during a rare cold spell and was found dead days later curled up under a bridge.

"It takes dramatic things like these for people to become aware of the issue," said Paloma Ramos, president of the Spanish Association for Relatives of Alzheimer Victims.

The association estimates that Spain has 400,000 diagnosed cases of Alzheimer's and will have 1.3 million in 2010.

The 15 countries of the European Union have more than two million cases altogether, according to Alzheimer-Europe, a non-governmental organization based in Luxembourg.

The Spanish-built device would feature so-called global positioning system technology, or GPS, of the kind used by emergency helicopters trying to pinpoint the scene of an automobile crash. It would also use GSM, or global system for mobiles, the main technology for mobile phones in Europe.

The project, initially to be run as a pilot experiment starting in Barcelona in October, is part of a broader cooperation agreement signed in March by the Spanish association and the National Police.

The device is being developed by a Spanish firm called Technosearch. Its president, Jose Luis Pellicer, said the challenges involved are daunting - mainly, building a battery that is tiny but strong enough to send a signal to a satellite.

"The first-generation tracer will probably be about the size of a pack of cigarettes," Pellicer said from Barcelona. "By the third or fourth generation, we hope to get it down to the size of a bracelet."

If all goes well, that will take about two years and the final product will probably cost about 90,000 pesetas ($ 500/540 euros), he said.

Alzheimer-Europe secretary general Jean Georges said the only tracers in use now in Europe are relatively rudimentary ones which, for example, are worn by Alzheimer's patients who live in nursing homes and activate when the person wanders out of the building. But the device doesn't help find the patient.

There is no satellite-based tracer device on the market in the United States either, says Jim Zagami, a systems engineer for Signatron Technology Corporation of Concorde, Massachusetts.

Zagami's firm is trying to develop a GPS tracer of its own under a grant from the National Institutes of Health in Bethesda, Md., he said. It is designed to be bracelet-sized from the outset but will not be ready for about a year.

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