The number of people with dementia is expected to rise by 50 per cent in the next two decades.

Professor June Andrews, a dementia expert, and adviser to the Dementia Services Development Trust said there is increasing concern that many people are failing to arrange powers of attorney in the event they fall ill.

“A power of attorney says if you can’t speak, are no longer making sense, or the doctors say you no longer have the capacity to take care of your own affairs, then this is what you want to be done on your behalf,” she said.

“Some people don’t do it because they don’t see the point, and others are superstitious and think something bad will happen because they have thought about it.

“They should ask themselves what is the worst thing that can happen? The worst thing would be for strangers to be making decisions about their finances and welfare without them having any influence. They should realise power of attorney takes that fear away.”

Sandra McDonald, former Public Guardian for Scotland, said fears that the power will be abused are often unfounded and that some 80 per cent of attornies appointed fulfilled their task competently.

Of the remaining 20 per cent who may be investigated, only two per cent, about 2,000 people a year, take advantage of the role.

Ian Macdonald, partner and head of private client at Wright, Johnston & Mackenzie LLP, said: “Granting a power of attorney is a relatively straightforward process and can be done quickly and inexpensively.

“If a person loses capacity before a power of attorney is granted and circumstances arise where that person requires assistance in managing their affairs, the options available are complicated, expensive and time consuming.”