Wildlife tracker traces patients

It is estimated that 10,000 people in the US wear the devices

A Scottish firm has adapted a radio tag designed for wildlife so it can be used by people with Alzheimer's or autism.

The Caretrak device by BlueSky Telemetry, which is based in Aberfeldy in Perthshire, is worn like a watch.

When the wearer goes outwith the area which has been set as "safe" an alarm goes off and the radio signal can be followed with an aerial.

The firm claims it has already been used to find more than 1,800 people in the United States over 20 years.

It has said it is worn by more than 10,000 people in the US.

BlueSky believes it gives those with the conditions more freedom, but allows relatives to track them down quickly if they wander off.

Jim Adams from the firm told BBC Scotland that the privacy of the wearer was protected.

He said: "This equipment, provided they stay within the safe area you've set, nothing happens, nobody's watching them, nobody's monitoring them, nobody's recording their movements.

"It's only if they move outside an area which is deemed to be safe then you get the alarm and you know that they have moved outside their safe area."

The signal can be tracked with an aerial

The Scottish director of the National Autistic Society, Carol Evans, recognises the benefits of such devices to parents.

"A lot of their children do wander off," she said.

"A lot of them experience no fear, the children are not afraid of traffic or busy roads, height - no fear at all.

"So the parents, they make themselves ill with worry when they can't find them.

"Inevitably the police are called, a full-scale hunt is called out and it's a terribly difficult and traumatic time for parents.

"So a tracking device would save an awful lot of heartache for parents."

There are other tracking devices on the market and the Alzheimer's Society has given a cautious welcome to such equipment.

However, it has called for more research on their pros and cons.