There has been a reported surge in the number of lasting power of attorney arrangements set up as dementia and Alzheimer’s disease becomes the biggest cause of death in Britain.

Power of attorney arrangements enable an individual’s financial and health affairs to be looked after by a third party, usually a solicitor, if they lose mental capacity in the future.

And according to official figures, more than 441,500 of such arrangements were set up in 2015, compared to just 36,000 in 2008.

Meanwhile, there have been 300,000 registrations in the first half of 2016 alone.

The staggering rise in new agreements follows news that deaths from dementia and Alzheimer’s jumped by 20 per cent last year.

The disease – which affects people’s cognitive ability to speak or remember – accounted for one in eight deaths in 2015, or a total of 61,686 people.

Rachael Griffin, of Old Mutual Wealth, warned that many people were still exposed.

“There are still many more people who don’t appoint a power of attorney,” she said.

“Although it is possible for someone to take control of your financial or welfare decisions after an individual becomes mentally incapable, this can be a lengthy and complicated process with extra cost, which can cause distress at an already difficult time.”

Without power of attorney, friends and family have to retrospectively apply to the Court of Protection and prove why they should be responsible for the donor – the person relinquishing their responsibility.

As well as incurring court fees, this process can take anywhere up to 16 weeks to complete, leaving the individual’s accounts in limbo.

Fortunately, applying for lasting power of attorney is a simple process.

Donors should register with the Office of the Public Attorney, and have their forms signed by an attorney and a certificate provider. This can be someone who the donor has known for two years or more, or a professional such as a doctor.