Most Alzheimer's drugs don't work

A new UK study published in THE LANCET concludes that the most widely used drugs to treat Alzheimer's disease have only minimal efficacy, and that an alternative approach for treatment is needed.

Around 400,000 people in the UK have AD. A class of drugs called cholinesterase inhibitors have been found to cause small increases in tests of mental ability among AD patients, although questions remain over their long-term efficacy and cost-effectiveness.

Richard Gray from the University of Birmingham, UK, and colleagues investigated whether donepezil (a cholinesterase inhibitor licensed in the UK in 1997) produced worthwhile improvements in disability, dependency, behavioural and psychological symptoms, wellbeing of carers, or delay in institutionalisation. In the study (called AD2000), 565 AD patients were randomly allocated either donepezil (5 mg or 10 mg) or placebo.

Donepezil did improve tests of mental and functional ability over the first 2 years of treatment, although at low levels. However, there was no significant delay in institutionalisation (42% donepezil, 44% placebo at 3 years), or progression of disability (58% for patients given donepezil, 59% for patients given placebo). There were also no differences between donepezil and placebo in behavioural and psychological symptoms, formal care costs, unpaid caregiver time, adverse events or deaths, or between the two doses of donepezil used in the study.

Professor Gray comments: "Based on our results, clinicians and health-care funders can validly question whether other uses of the scarce resources allocated to dementia care would provide better value than routine prescription of cholinesterase inhibitors".

Alzheimer's disease or senile dementia of Alzheimer's type is a disorder or loss of mental functions resulting from brain tissue changes; the causes are yet to be fully elucidated (mutations in at least four genes predisposing to AD have been identified). There are also studies that link aluminium to the progression of Alzheimer's, but the results are far from conclusive.

The disease was thought to be uncommon, until the 1960s when it was realized that much of what had been regarded as the normal process of aging was actually the result of this disease.