Scientists at the University of Dundee said the drugs are “known to be of limited benefit” and may cause “significant harm” to patients.

The drugs have long been used on dementia patients in an attempt to deal with their behavioural and psychological disturbances.

The scientists scrutinised data from 315 GP practices, including the records of around 270,000 older people - about one third of the older population. Of these, 10,000 had some form of dementia and 1,785 of them were given anti-psychotic drugs.

Those with dementia were found to be two times as likely to be given anti-depressant or other sedative drugs, such as diazepam (valium), and were around 17 times more likely than the others to be on anti-psychotics.

The research was carried out by Bruce Guthrie, professor of primary care medicine at Dundee, alongside a team from NHS Fife. The findings were published in the Age and Ageing journal.