Currently, the drug is only prescribed to patients with mild to moderate Alzheimer's, and stopped when their condition deteriorates to the severe stage.

For this latest study, the researchers randomly assigned 407 patients with severe Alzheimer's who were living in a nursing home to receive galantamine, 24mg daily, or placebo for six months.

Overall, the researchers found that patients who were given galantamine had improved cognitive function, particularly memory and the ability to carry out motor performance tasks.

However, the carers who were looking after the patients reported that those on galantamine showed no improvement in their ability to undertake everyday tasks, compared with the patients on placebo.

The researchers, from the University of Manchester, said: 'The data shows there are untreated patients with severe Alzheimer's disease in nursing homes who could benefit from starting treatment with galantamine.'

But in an editorial, Dr Martin Farlow, from Indiana University, warned that the 'clinical usefulness of galantamine has still not been proven in this population'.

sanjay.tanday@haymarket.com

• The Lancet Neurology Online 2008

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