Unexpectedly large numbers of people with learning disabilities are being prescribed strong psychiatric drugs, possibly as a “chemical cosh” to quieten those with challenging behaviour, according to new research.

A study published online by The British Medical Journal found that the number of people registered with GP practices with an intellectual or learning disability, who are being treated with psychotropic drugs far exceeds those with mental illness.

If people without mental illness are given psychotropic drugs, such as the powerful antipsychotics more usually prescribed for people with schizophrenia or bipolar disorder, it is probably to control their behaviour, say the study’s authors, from University College London (UCL).

“I think there’s been concern for a long time that psychotropic medications are being overused in people with intellectual disabilities,” said Rory Sheehan, an academic clinical fellow at UCL and lead author of the paper.

He and his fellow authors were concerned, he said, because it is quite difficult to justify the use of strong drugs such as antipsychotics, which can have problematic side effects, except in specific circumstances or as a last resort. “You wouldn’t want to give these medications without quite strong justification,” he said.

There will be some people who are on such drugs for very good reasons, he said, but the researchers found that of 9,135 people in their study with intellectual disabilities and treated with antipsychotic drugs, 71% – or 6,503 people – did not have a record of severe mental illness.

They analysed data from electronic health records held in 571 GP practices and found 33,016 people with intellectual disabilities, with an average age of 36. Intellectual disability covers people with an IQ below 70 who also have some difficulty in functioning on a day-to-day basis. Their needs could range from assistance in managing their tenancy to being unable to wash and dress themselves.

About a third of those in the study, or 11,915 people, had a record of

challenging behaviour, 47% of whom – or 5,562 people – had received antipsychotic drugs. Only 13%, or 1,561, had a record of severe mental illness.

Older people, those with a record of challenging behaviour, autism, dementia epilepsy and mental illness, were significantly more likely to be prescribed antipsychotics. Charities that support older people campaign against the use of antipsychotics to keep those with dementia quiescent, a practice some care homes are known to adopt.

Concerns over antipsychotic drugs may be behind the steady fall in their prescription to people with intellectual disabilities over the last 15 years, which the study also revealed. The researchers, however, found they were not the only drugs that may be inappropriately prescribed. Drugs to treat anxiety were frequently prescribed, as were antidepressants.

Like the antipsychotic group, both of these types of drug were given at substantially higher rates than would have been expected given the number of diagnoses for mental illness.

The researchers focused on the use of antipsychotics because they carry the risk of serious side effects including sedation, weight gain and other metabolic changes that can lead to diabetes and movement problems such as restlessness, stiffness and shaking.

“Side effects can be managed, but the risks and benefits must be carefully considered before prescribing antipsychotics to people without severe mental illness,” Sheehan said.

“Research evidence does not support using antipsychotics to manage behaviour problems in people with intellectual disabilities. Many people with intellectual disability and behaviour disturbance have complex needs and other interventions, such as looking at the support people receive and their communication needs, should be prioritised,” he said.

“Antipsychotics, or indeed any medications, should not be prescribed lightly and are no substitute for comprehensive care.”

