PARIS - LONG-TERM use of powerful drugs to calm patients with Alzheimer's disease may increase their risk of death, according to a study published online on Friday by the journal The Lancet Neurology.

British doctors monitored the progress of 128 patients with Alzheimer's, aged between 67 and 100, living in care facilities between October 2001 and 2004.

Half of the patients were given antipsychotic drugs and the other half were given a dummy lookalike pill called a placebo.

After one year, the chances of survival among patients in the drug group were 70 per cent, as against 77 per cent in the placebo group.

After two years, the survival rate fell to 46 per cent and 71 per cent respectively.

After three years, the gap widened further, with only 30 per cent surviving in the drug group versus 59 per cent in the placebo group.

Previous research has shown that short-term use of antipsychotics is beneficial for soothing agitated patients with Alzheimer's.

But drugs also have a long list of side effects and some studies have also pointed to a higher mortality rate.

'There is an increased long-term risk of mortality in patients with AD (Alzheimer's disease) who are prescribed antipsychotic medication,' says the paper, written by Mr Clive Ballard, a specialist in ageing at King's College London.

'These results further highlight the need to seek less harmful alternatives for the long-term treatment of neuropsychiatric symptoms in these patients.'

Alzheimer's is a degenerative disorder of the brain characterised by forgetfulness, agitation and dementia.

It is caused by a massive loss of cells in several regions of the brain, driven by a buildup of plaques of amyloid protein.

The disease occurs most frequently in old age, but some genetic variants have been shown to increase risk as well.

Around 25 million people around the world have dementia, most of whom have Alzheimer's, according to figures cited in the paper. -- AFP