Over 70% of prescriptions for antipsychotic medications are given to those without a record of severe mental illness.

The proportion of people with intellectual disability in the UK who have been treated with psychotropic drugs far exceeds the proportion with recorded mental illness, finds a study published by The BMJ today.

This suggests that, in some cases, these drugs are being used to manage other presentations, such as challenging behaviour,rather than for mental illness, say the researchers. They call for changes in the prescribing of psychotropic drugs for people with intellectual disability as well as more evidence on their safety in this group.

People with intellectual disability develop severe mental illness at higher rates than do the general population and may show challenging behaviour.

Concern has existed for many years that psychotropic drugs in general – and antipsychotics in particular (mainly used to treat schizophrenia and bipolar disorder) – are overused in people with intellectual disability, but accurate estimates have been difficult to obtain.

So a team of researchers based at University College London set out to describe rates of recorded mental illness, challenging behaviour, and use of psychotropic drugs in people with intellectual disability in UK primary care.

They analysed data from 571 UK general practices using the The Health Improvement Network (THIN), a large database of electronic health records, and identified 33,016 people with a record of intellectual disability. Average age at study entry was 36 years and average follow-up was five and a half years.

Of 9,135 participants treated with antipsychotic drugs by the end of the study period, 6,503 (71%) did not have a record of severe mental illness.

Of the 11,915 with a record of challenging behaviour, 5,562 (47%) had received antipsychotic drugs, whereas only 1,561 (13%) had a record of severe mental illness.

And of those with a record of prescription of antipsychotics, 26% did not have a record of severe mental illness or challenging behaviour.

New prescriptions for antipsychotics were significantly more common in older people and in those with a record of challenging behaviour, autism, dementia, and epilepsy, as well as mental illness.
People with a record of challenging behaviour were more than twice as likely to receive a prescription for antipsychotics compared with those without a record of challenging behaviour, say the authors.

Prescription of antipsychotic drugs is disproportionate to the level of recorded severe mental illness and is associated with the presence of challenging behaviour, older age, and diagnoses of autism and dementia, they add.

“Inappropriate use of drug treatment has implications for the individual and for healthcare systems,” they warn. “These findings highlight the need for an improved evidence base for use of drugs and optimisation of drug treatment in people with intellectual disability.”