Thousands of dementia sufferers are being denied access to crucial drugs because of “critical errors” by the Government’s drug watchdog, the High Court is to be told today.

The National Institute for Health and Clinical Excellence (NICE) is accused of using “flawed and out-of-date figures” to play down the impact of the drugs on the lives of carers of dementia sufferers. When it decided to restrict access to three key drugs, NICE concluded that even on the most optimistic assessment, the benefit to carers of more widespread use of medication was negligible.

Central to the case being presented by the Alzheimer’s Society today is its calculation that the drugs, which slow the progress of dementia, can save carers an hour and a half each day in caring duties.

The society, which represents dementia sufferers and their families, will also tell the court that NICE underestimated the cost of full-time residential care at £355 a week. In fact, the weekly cost can be £1,500. The charity says that wider use of the drugs would help dementia sufferers to stay in their homes longer, saving local authorities millions of pounds.

The case, the first legal challenge to a NICE decision, has been brought by Eisai, the licensed holder of one of the three drugs in question. The pharmaceutical company Pfizer is backing Eisai’s case.

The Alzheimer’s Society is acting as an “interested party” in the judicial review. Its evidence on how carers could benefit from wider use of the drug is new to the case. It will run until Thursday. The judge will then take several weeks to reach a decision. The court can order NICE to reconsider.

In 2005 NICE said that the three drugs, Aricept, Reminyl and Exelon, should not be available on the NHS. After a protest by those affected, NICE reconsidered and decided that the drugs could be prescribed, but only to people with middle-stage dementia. Five appeals were rejected, and a judge ruled in April that there were grounds for a judicial review.

NICE has never said how much its decision to restrict access to the drugs would save the NHS, but experts put it at about £9.4 million a year.

Neil Hunt, chief executive of the Alzheimer’s Society, said: “These treatments have benefited so many families. Where is the justice in NICE’s decision to snatch them away? Another 100,000 people will develop dementia this year.”

Andrew Dillon, chief executive of NICE, said: “Non-drug interventions have an important part to play and the evidence indicates that drugs are not effective for some patients.”

Elsie Johnson is certain that her husband, Alan, 68, has benefited greatly from the Aricept he was prescribed as soon as his Alzheimer’s was diagnosed in 2000. Under NICE’s guidelines, he would have had to wait until his condition had deteriorated. Seven years on, the couple can still go on holiday, shop and take outings near their Gateshead home.

“A month or two after he was put on Aricept, he really perked up and started to take more interest in life. We lead a pretty good life together,” Mrs Johnson told The Times.

“It is a terrible situation when psychiatrists are telling their patients that they know they have Alzheimer’s and they know what will help, but they can’t do anything until they get worse, so come back in a year.”

She added: I don’t understand why scientists are spending time and money developing new drugs if NICE is going to stop people from getting them.”

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