Researchers have warned dementia patients against the use of prescribed antipsychotic drugs, also called Chemical Cosh drugs as they can double the risk of death in such patients.

Although research in the past has warned about the side effects of using the drugs, the new study by the Harvard Medical School has found that people over 65 can actually double the risk of death by taking the drug haloperidol.

People who particularly take high dosage of such drugs were at the greatest risk, according to the survey.

The research team did the survey by looking at 75,445 older nursing home residents between 2001 and 2005. They then compared the safety and death risks of haloperidol and another common anti-psychotic, risperidone.

The data suggest that the risk of mortality with these drugs is generally increased with higher doses and seems to be highest for haloperidol and least for quetiapine, the Press Association quoted a study spokesperson saying.

The Huffington Post reported that this isn't the first time anti-psychotic drugs have hit the headlines; in 2009, a Government-commissioned review found that of 180,000 prescribed anti-psychotics, 144,000 were administered inappropriately.

Despite research findings, clinicians have not given up on the use of antipsychotic drugs for dementia.

If drug use is necessary, it makes sense to start at a low dose and gradually increase it. The need to continue the drug should be evaluated regularly. Clinicians are advised to document their reasons for prescribing the drug and their understanding of the risks and benefits, said Dr. Michael Miller, editor-in-chief of the Harvard Mental Health Letter.