Liberal Democrat MP Dr Vincent Cable will condemn the current wide variations in the NHS availability of drugs such as Aricept.

Until now, health authorities have been free to decide whether the drug should be available on the NHS.

Some, such as Croydon, have put a total bar on the drug, arguing that lack of strong evidence of the drug's effectiveness does not warrant its cost.

Dr Cable will urge the government to make consideration of Alzheimer's drugs a top priority for the new National Institute of Clinical Excellence (NICE) launched in April to rule on which drugs should be available on the NHS.

Devastating disease

Dr Vincent Cable leads calls for Alzheimer's drugs to be more freely available

Dr Cable said Alzheimer's was a devastating disease which affected 400,000 people in the UK.

Although there was no cure, drugs such as Aricept could substantially improve the condition of patients and reduce the burden on their carers, he said.

"What we have got in the NHS at the moment is fairly heavy rationing with a lot of people having to buy their drugs on private prescription costing �100 a month," Dr Cable told BBC News Online.

"I believe the cost benefit of making Aricept freely available on the NHS would be substantial, quite apart from the humanitarian side of it."

Dr Cable said Aricept was already freely available in Northern Ireland, where health and social services were more closely integrated, and where the wider benefits - such as the reduction in social care costs - could be more easily appreciated.

"The rest of the UK treats Alzheimer's drugs purely in terms of the cost of the drugs themselves, which is a narrow, self-defeating approach," he said.

Clinical need

Rebecca Gray, head of publicity for the Alzheimer's Disease Society, welcomed Dr Cable's campaign.

She said less than a third of Alzheimer's patients benefitted from Aricept, which has been shown to be effective for patients who are not in the more advanced stages of the disease.

"Availability should be based on clinical need, not on where you live," she said.

"The inconsistency creates a great deal of distress for carers. We get callers to our helpline who know that people who live two miles away from them are getting the drug, when they are not."

Alzheimer's disease is the most common form of senile dementia, affecting up to 10% of adults over 65 and 50% of those over 80.

It is a progressive, degenerative disease that attacks the brain and results in impaired memory, thinking and behaviour.

Recent research shows that 80% of Alzheimer's patients who take Aricept show significant improvements in their condition within the first 24 weeks.