New research suggests that many drugs are vasty overprescribed to people with intellectual disabilities despite scant evidence that they provide any benefit.

An analysis of medical records for more than 33,000 adults with intellectual disabilities in the United Kingdom between 1999 and 2013 finds one in four were prescribed antipsychotic medication.

Often the drugs were used to address behavior problems like aggression and self-injury, according to findings published Tuesday in The BMJ.

The trend is troubling, researchers said, because 71 percent of those with intellectual disabilities who were prescribed antipsychotics had no record of severe mental illness, which is what the drugs are designed to treat.

“Research evidence does not support using antipsychotics to manage behavior problems in people with intellectual disabilities,” said Rory Sheehan of University College London, who led the study. “Many people with intellectual disability and behavior disturbance have complex needs and other interventions, such as looking at the support people receive and their communication needs, should be prioritized. Antipsychotics, or indeed any medications, should not be prescribed lightly and are no substitute for comprehensive care.”

Among study participants, antipsychotics were more common in those who were older and in individuals with intellectual disability and a diagnosis of autism or dementia.

Beyond questions about efficacy, inappropriately giving people antipsychotics puts them at risk for side effects like drowsiness and weight gain, which can lead to other long-term health consequences like diabetes, Sheehan said.

The researchers did note that use of antipsychotics declined gradually over the 15 years studied, suggesting that doctors may be adjusting their methods.

In addition to antipsychotics, the study found that medications for anxiety and depression were also frequently prescribed to people with intellectual disabilities.

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