Two in every five elderly residents of care homes are being given sedatives to make them easier to look after, researchers say.

The figures are highlighted in a controversial new report from the University of Dundee, which also says many people may be taking the drugs for much longer than necessary.

The new study shows that approximately 1 in 6 older people receive at least one psychotropic medication in a 2-year period. The figure rises to two in five among nursing home residents.

However, the study found that the majority of psychotropic drugs used by nursing home residents were started prior to the patient being admitted, and for those who started antipsychotics just prior to admission it was more likely the person would continue to receive the drugs.

"This study presents a complex picture of the prescribing and use of these medicines," said Colin McCowan, Deputy Director of the Health Informatics Centre at the University.

"Psychotropic drug use is significantly higher in care home residents but they would seem to be initiated primarily before people are admitted.

"This may be evidence against the belief that initiation is largely driven by care home staff to make residents easier or more convenient to manage.

"There may be valid reasons for the initiation of these drugs but prolonged use of psychotropic medication in older people is not recommended and may cause harm.

"The key issue our study suggests is that there should be systematic medication reviews for patients on these drugs, to highlight drugs that may be discontinued if the reasons for their initial prescription are no longer valid."