Cholinesterase inhibitors do not seem to delay Alzheimer disease

Researchers have examined the evidence in favour of giving people considered to be close to developing dementia the drugs that are most commonly used to treat the condition itself.

They have concluded that these drugs (cholinesterase inhibitors) do not seem to delay the appearance of Alzheimer disease or other forms of dementia.

Three cholinesterase inhibitors – donepezil, rivastigmine and galantamine – are currently approved for use in mild-to-moderate Alzheimer disease. Some experts are not convinced that they are effective, but other experts and patient support groups have called for the drugs to be given to people with “mild cognitive impairment (MCI)” – the term that is used to describe the condition where people have memory problems that are more severe than those normally seen in others of their age, but otherwise have no symptoms of dementia. It is believed that people with MCI are at high risk of developing Alzheimer disease.

Dr Raschetti and colleagues at Italy's National Centre for Epidemiology, Surveillance and Health Promotion in Rome conducted a systematic review of the data from clinical trials that had addressed the use of cholinesterase inhibitors with MCI patients. In none of the six trials that they examined did the use of the drugs significantly reduce the rate of progression from MCI to dementia.

One problem that came to light during their review was that there is no generally accepted precise definition for MCI. There was therefore some variation between the trials in the mental state of the people given the drugs. Dr Raschetti and his team have called for more clinical trials to be done, but using a single agreed definition of mild cognitive impairment. Until such trials have found a benefit from using cholinesterase inhibitors in this way, there seems to be no justification for doctors to do so in clinical practice.