Best-selling author Terry Pratchett will next week present Prime Minister Gordon Brown with a 18,000-signature petition demanding more cash for research into Alzheimer’s disease.

With him will be Wharfedale MP Greg Mulholland.

The pair will have the backing of the Alzheimer’s Research Trust, of which Pratchett is a patron and to which he has pledged $1m of his own money to support research into the disease and, ultimately, a cure.

Pratchett, 60, best known for his Discworld series of comic fantasy novels, revealed last year that he had been diagnosed with early onset Alzheimer’s disease. Since going public, the author, who has sold more than 55,000,000 books around the world, has vowed to “scream and harangue while there is time” to raise awareness of the disease.

He said: “I am, along with many others, scrabbling to stay ahead long enough to be there when the cure comes along. Say it will be soon – there’s nearly as many of us as there are cancer sufferers, and it looks as if the number of people with dementia will double within a generation.

“In most cases, alongside the sufferer, you will find a spouse suffering as much. It is a shock to find out that funding for Alzheimer’s research is just 3 per cent of that to find cancer cures.”

When he and Otley MP Mr Mulholland, the Liberal Democrats’ older people’s health spokesman, meet Gordon Brown on Wednesday, they will be demanding more cash for dementia research with a petition that describes the Government’s funding of dementia research as “appalling”.

The MP was delighted that his request for the meeting – made during Prime Minister’s Questions last week – was granted.

They will remind Mr Brown that only three per cent of the national medical research budget is spent on Alzheimer’s study.

Mr Mulholland said: “”Dementia affects hundreds of thousands of people in the UK, yet it is still fundamentally misunderstood and simply doesn’t have enough money invested in research, despite the devastating impact that it can have on the lives of those who suffer from it.

“Both in my role as a constituency MP and as older people’s health spokesman for the Liberal Democrats, I have heard from many people whose lives have been affected by dementia and how it affects sufferers and their families.”

The author’s petition reads: “I am appalled that research into Alzheimer’s and related diseases, which affect 700,000 people in the UK, currently receives just three per cent of government medical research funding. I strongly urge the Government to increase funding for dementia research as a matter of urgency.”

The Prime Minister has spoken of planned £15 billion expenditure over the next ten years on medical research for conditions including Parkinson’s disease and Alzheimer’s. Petitioners are keen to see how this figure will break down for dementia research.

Rebecca Wood, chief executive of the Alzheimer’s Research Trust, said: “It is fantastic to see Gordon Brown agreeing to meet Terry Pratchett to discuss the need for more research into dementia. We welcome the Prime Minister’s commitment to wider medical research funding over the next decade, and look forward to finding out what this means for dementia research specifically.

“Two-thirds of all voters, and four-fifths of over 55s, support an increase in funding for dementia research. Politicians from all parties are realising that this challenge, which costs the British economy £17 billion a year, must be tackled through an urgent increase in dementia research funding.”

The Alzheimer’s Research Trust has funded over 150 research projects into preventing, treating and curing the disease.

Their achievements so far include helping the diagnosis of Alzheimer’s to become more accurate; showing that a drug prescribed to dementia patients accelerated cognitive decline, finding a DNA link to Parkinson’s disease – helping scientists to identify routes to potential treatments – screening 1.5 million compounds to identify 40 that offer the greatest potential to be developed into drugs for the treatment of Alzheimer’s; identifying markers in the blood for the development of Alzheimer’s for the first time – offering hope of a possible blood test to diagnose the disease.

According to the research trust, while an estimated 700,000 people in the UK are affected by Alzheimer’s, £11 per head is spent each year on UK research compared with £289 for each cancer patient, although similar numbers of people are affected.

University of Leeds Professor Nigel Hooper, who works in dementia research, said the area was undoubtedly under-funded.

“When you compare the figures for funding going into Alzheimer’s or dementia research to the funding going into cancer research there is a significant difference,” he said: “Traditionally, dementia has been just seen as a disease of old age that most people are likely to get and it is just one of those things.”

But he said there was potential for progress in combating Alzheimer’s “probably more so than in some other areas, because relatively we don’t know as much and therefore there is more scope to find new ways of treating the disease”.

“In that respect,” said Prof Hooper, “there is a lot more to play for.”

The research trust says that three-quarters of the research that could go ahead is not being undertaken because of a lack of funding.

It says: “We fund the most innovative and promising UK research in any area of dementia from the most talented scientists in top research environments. Only the very best are funded, and we are disappointed we have had to turn down so many promising projects due to a lack of money. Three out of four applications have to be rejected.”

But the involvement of the best-selling author of the 1990s could change some of that.

Prof Hooper said: “Obviously, it really does help to have somebody with his public profile fronting it and making a bit of noise about it.”

“That can only be good, not only for those of us trying to do research but ultimately for people who have the disease or who will have the disease.”

Mr Mulholland said: “While great advances in our understanding of Alzheimer’s disease and the new approaches to treatment and prevention are being made here in the UK, it is still nowhere near enough. We are at real risk of failing sufferers of Alzheimer’s, the majority of whom are vulnerable older people, and leaving them marginalised and ignored.

“The number of people with Alzheimer’s is expected to double within a generation; we simply cannot afford to ignore it any longer.”

In Ilkley, the charity Acorn holds fund-raising events for people with dementia and scleroderma.

One of the group’s founders, Louise Hanen, whose father developed dementia in his early 50s, said research into the disease was massively under-funded. He, like Pratchett, had early onset Alzheimer’s, which is how it is classified if it strikes before the age of 65.

She welcomed attempts to get extra funding.

“It is great news and it is about time that it has started to happen,” she said. “It has been pushed under the carpet long enough. And the stigma attached to the illness has meant that people haven’t come forward.

“Now people in a position like Terry Pratchett are getting out and saying something. More and more people are shouting out about it, because it is a hugely under-funded area.”

l Pratchett, who recently published the 36th book in his acclaimed Discworld series, received an OBE for his services to literature in 1998, and in 2001 he won the Carnegie Medal.

In addition to the Discworld books, Pratchett has written many other novels for adults and younger readers, along with plays, illustrated screenplays, comics and graphic novels.