The society believes companies are priming the market in advance of the UK launch of two drugs for Alzheimer's, and raising the hopes of thousands of people that the disease can be halted. However, the drugs do not treat the underlying disease and, in the short-term, are likely to benefit only a small minority of people - about 5 per cent of those with dementia.
Parke Davis, the company that makes tacrine (Cognex), held a press conference yesterday to publicise the results of an American study which showed that high doses of the drug over a 30-week period produced clear benefits in 42 per cent of Alzheimer's patients, compared with 18 per cent of patients on placebo drugs.
Previous studies have been almost equally divided between those reporting benefits for some patients and those reporting no effect. The new study, reported in the current issue of the Journal of the American Medical Association, used a higher dose for a longer period than any other study so far.
However, less than half the enrolled patients completed the study. Side-effects associated with the drug, including gut and liver problems, were responsible for almost three-quarters dropping out.
Clive Evers, an assistant director at the Alzheimer's Disease Society, said yesterday: 'We have to bear in mind that the study was sponsored and set up by Parke Davis . . . it is a valuable contribution to furthering the knowledge and understanding of tacrine and confirms some of what we already know, but there are still many questions to be answered.' He pointed out the additional costs of monitoring the liver function of patients on tacrine.
Between 400,000 and 500,000 people have Alzheimer's in the UK, with progressive dementia, memory loss and an inability to look after themselves. The disease is an enormous problem for developed countries with an ageing population because of the demand it places on the health service and carers.
The total cost of Alzheimer's care in England is estimated at pounds 1.039bn (1990-91 prices), compared to pounds 791m for stroke patients and pounds 34m for multiple sclerosis. The potential worldwide market for an Alzheimer's drug is huge, and predicted to increase from dollars 810m ( pounds 540m) to more than dollars 2.9bn ( pounds 1.9bn) between 1992 and 2007.
Alzheimer's is associated with a loss of vital brain cells producing a chemical which transmits messages between nerve cells. Tacrine is believed to optimise the function of the undamaged cells, increasing the amount of brain chemical. Last year, it was approved by the American Food and Drug Administration for use in mild to moderate Alzheimer's cases.
The Committee on Safety of Medicines is now considering an application from Parke Davis for tacrine, and from another company, Hoechst, for the related drug, velnacrine, to be made available in the UK. The society said that the drugs are likely to receive publicity 'disproportionate to their importance merely because they are the first such drugs'.Reuse content