Diagnosing mental and intellectual conditions is sometimes difficult. Symptoms can overlap or be nonexistent, and sometimes they don’t show up in a manner typical to the illness. It’s important that these illnesses are diagnosed correctly, though, because the right combination of medicine and therapy is sometimes the only way for a patient to recover.

It looks like we’ve still got a long way to go when it comes to correctly prescribing drugs for the brain. Large numbers of people in the UK with intellectual disabilities are still being inappropriately prescribed antipsychotic drugs, according to a new study.

Intellectual disabilities differ from mental illnesses in several ways. An intellectual disability normally manifests before the age of 18 and is a lifelong condition. Intellectual disabilities are hallmarked by limitations in intellectual functioning — often indicated by an IQ below 70 — and difficulties with life skills. About one percent of the population is affected by an intellectual disability.

Antisychotioc drugs, however, are designed only to treat severe mental illnesses including schizophrenia. There has been very little evidence that suggests these drugs can help address issues not due to mental illness.

Despite this knowledge, a study published in The BMJ found that antipsychotics were often being prescribed to those who had behavioral problems but had no history of severe mental illness. Some of the behavioral issues seen in those diagnosed with intellectual disability include destruction of property, self-harm, aggression, and other behaviors outside of the social norm. Those with both an intellectual disability and autism or dementia were more likely to be prescribed antipsychotics, as were older people.

"The number of people with intellectual disabilities who have been prescribed antipsychotics is greatly disproportionate to the number diagnosed with severe mental illness for which they are indicated," explained study author Dr. Rory Sheehan (UCL Psychiatry).

Sheehan said that those who exhibit problem behaviors are more likely to be given an antipsychotic drug, despite the possible harm that goes along with it, and the practice being against clinical guidelines.

Luckily, the study found that the rate of prescribing antipsychotics to those with intellectual disabilities has been falling slowly over the last 15 years. This indicates that general practitioners are utilizing alternative therapies.

Other drugs used to treat mental illness, however, are also being prescribed to those with intellectual disabilities in large numbers. Anxiety treatment drugs were the most prescribed, followed by antidepressants. Like antipsychotics, both of these drugs were being prescribed at a higher rate than mental disorders were being recorded. Researchers focused on antipsychotics, though, because of their serious risk of side effects.

The side effects of antipsychotic drugs include weight gain, metabolic changes, sedation, and movement problems.

"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.

People suffering from intellectual disabilities have a complex set of needs that should be prioritized by doctors, according to Sheehan. Antipsychotics are not something that should be prescribed lightly, and are not an appropriate substitution for comprehensive care.

Source: Sheehan R, Hassiotis A, Walters K, Osborn D, Strydom A, Horsfall L. Mental illness, challenging behavior, and psychotropic drug prescribing in people with intellectual disability: UK population based cohort study. The BMJ. 2015.