Placebo better than antipsychotic drugs for treating aggression in the intellectually disabled

Jan 6 2008

Antipsychotic drugs which are commonly used to treat aggression in people who are intellectually disabled have been revealed to be ineffective.

The researchers say such candidates should not be prescribed these drugs as placebos seem to do a better job.

A study by researchers at Imperial College, London has found that when two antipsychotic drugs haloperidol and risperidone were compared with a placebo, the placebo reduced aggression by nearly 80 percent compared with 50 percent to 60 percent for the drugs.

In order to gauge aggression the researchers used a widely accepted measuring scale.

The research was conducted on 86 non-psychotic patients with aggressively challenging behaviour at 10 centers in England and Wales and one in Australia.

All but one of the patients was in a community setting, more than half were men, and the majority had mild or moderate intellectual disability.

The researchers say at no point was the placebo significantly worse than risperidone or haloperidol, nor was there a difference in response for the small group of patients with autism spectrum symptoms.

Despite little evidence to support their use, antipsychotic drugs are prescribed from 22% to 45% of inpatients in this population and to about 20% of those in the community.

Risperidone is sold under the brand name Risperdal and is a popular schizophrenia drug, Haloperidol is an older drug marketed as Haldol and both are manufactured by drug company Johnson & Johnson.

According to Dr. Peter Tyrer, a community psychiatrist, who led the study, such drugs have been used to treat aggression in people who are not psychotic for 60 years.

Dr. Tyrer says in most circumstances people should not be given these drugs because there is no indication they work; he says their study shows that a placebo is more effective.

Tyrer says about 1.5 percent of the population have IQ's below 70 and are defined as disabled because of their lower intelligence; these people often have difficulty expressing themselves and are often aggressive when trying to do so.

Experts in the U.S. say the study is important because there is little evidence on the effectiveness of the drugs in treating aggression for people with lower-than-normal intelligence who are a highly vulnerable group.

Tyrer says the study is the first to be carried out which was not been funded by the pharmaceutical industry.

He suggests one of the reasons the placebo works so well is the simple psychological effect these often ignored patients gain from the attention of a doctor when given the treatment.

Both drugs cause dry mouth, dizziness, constipation as well as serious side effects such as tremors, and Tyrer suggests these problems possibly offset any psychological benefits the drugs might have.

The medication used in the study was provided by Janssen-Cilag and the study was supported by Mencap and the National Coordinating Center for Health Technology Assessment; it is published in the medical journal The Lancet.