Treating people who have early memory problems with Alzheimer's drugs seems to have no affect on the onslaught of the disease, researchers said Tuesday.

Three main drugs — Aricept, or donepezil; Exelon, or rivastigmine; and Reminyl, or galantamine — are currently approved for use in mild-to-moderate Alzheimer's disease. They are also often prescribed on a so-called "off-label" basis to people with pre-dementia.

But doctors are divided over their effectiveness, leading to differing rates of use and bitter arguments over patient access to treatment, notably in Britain where a dispute over their cost-effectiveness has led to legal clashes.

Some experts and patient groups have called for such anti-cholinesterase drugs to be given to people with mild cognitive impairment (MCI) — a condition where people have memory problems that are more severe than those normally seen in others of their age.

People with MCI are thought to be at high risk of developing Alzheimer's or dementia.

But Italian researchers found in none of six clinical trials they examined did using the drugs significantly reduce the rate of progression from MCI to dementia.

Accurate assessment of the effect of anti-cholinesterase medicines was muddied by the lack of a precise definition for MCI, Roberto Raschetti and colleagues at the National Centre for Epidemiology, Surveillance and Health Promotion in Rome reported in the online journal PLoS Medicine.

Their findings may prompt a rethink among doctors who are currently using anti-cholinesterase drugs off-label in MCI. Off-label use refers to the common practice of prescribing drugs for uses for which they are not officially approved.

(Agencies via Xinhua News Agency November 29, 2007)