Intellectual Disability Boosts Movement Side Effects From Antipsychotics

A population-based cohort study published in BMJ Open substantiates a long-held assumption: patients with intellectual disability (ID) treated with antipsychotics have higher rates of adverse movement side effects, including acute dystonias, akathisia, parkinsonism, tardive dyskinesia, and neuroleptic malignant syndrome.

“People with ID appear more susceptible to movement side effects of antipsychotic drugs than people without ID, and this should be considered when treatment decisions are made, especially given the relatively high rates of other comorbidities in this population,” researchers wrote. “There is evidence that movement side effects of antipsychotic drugs are poorly assessed in people with ID who are under the care of secondary care services; this situation must change if medication is to be used in the safest and most effective way possible.”

The study is the first to directly compare rates of extrapyramidal side effects from antipsychotic drugs in people with and without ID. The analysis included 9013 adults with ID and a control group of 34,242 adults without ID, who were prescribed antipsychotic drugs in primary care settings in the United Kingdom.

Movement side effects were significantly more common in people with ID, compared with people without ID, researchers reported. The overall incidence of movement side effects was 275 per 10,000 person-years in the intellectual disability group, compared with 248 per 10,000 person-years in the control group.

The greatest differences between the 2 groups, according to the study, were rates of parkinsonism and akathisia. Although infrequent, neuroleptic malignant syndrome was 3 times more common in people with ID.

The difference in movement side effect incidence between the groups was not due to a difference in the proportions prescribed first- and second-generation antipsychotics, researchers added.

“Assessment for movement side effects should be integral to antipsychotic drug monitoring in people with intellectual disability,” researchers concluded. “Regular medication review is essential to ensure optimal prescribing in this group.”

—Jolynn Tumolo

Reference

Sheehan R, Horsfall L, Strydom A, Osborn D, Walters K, Hassiotis A. Movement side effects of antipsychotic drugs in adults with and without intellectual disability: UK population-based cohort study. BMJ Open. 2017;7(8):e017406.