HUNDREDS of thousands of dementia patients are being wrongly prescribed powerful “chemical cosh” drugs, with an estimated 1,800 dying every year as a result, a report has said.

Just one in five of those given the medicines in care homes and hospitals derive any benefit from them, it said.

Around 180,000 people with dementia are thought to be on the medicines with up to 150,000 of those receiving them unnecessarily, the report said.

For years controversy has surrounded the use of anti-psychotic drugs which can double the risk of death and triple the risk of stroke.

The government-ordered review estimates overprescribing is linked to an extra 1,800 deaths a year among elderly people while a similar number suffer a stroke because of the drugs.

Anti-psychotic medicines are licensed to treat people with schizophrenia but are used off-licence for dementia patients in care homes and hospitals.

They are prescribed to control symptoms such as aggression, agitation and hallucinations but critics say they are often given to heavily sedate people – the so-called “chemical cosh”.

In his review, Sube Banerjee, professor of mental health and ageing at the Institute of Psychiatry at King’s College London, said people stayed on the drugs for far too long and the “relatively small” benefits were generally outweighed by harm.

Prof Banerjee said 20 or 30 years ago, 30% of care home residents had dementia but that figure was now 80 or 90%.

“What we have here is an overall failure of health and social care systems to adjust to a changing world.”

But Prof Banerjee, whose recommendations cover England, said patients should not come straight off the drugs and it was important relatives did not panic.