This transcript has been edited for clarity.
Tardive dyskinesia is a chronic, potentially irreversible, hyperkinetic movement disorder. And the challenge with tardive dyskinesia is that it’s underdiagnosed and undertreated. With the expanded use of dopamine receptor–blocking agents, there are about 7.5 million Americans who are now exposed and at risk for tardive dyskinesia.
It’s thought that about 500,000-750,000 of these patients may in fact have tardive dyskinesia, but only 15% are treated. So why are people not being treated for tardive dyskinesia? Well, there are a number of possible answers.
Until a few years ago, there were no Food and Drug Administration (FDA)–approved treatments for tardive dyskinesia, and these antipsychotic medications that the patients were taking, in many cases, were potentially lifesaving drugs, so they couldn’t simply be stopped. As a result of that, I think physicians developed a certain psychic blindness to identifying tardive dyskinesia, because it was their drugs that were causing the disease and yet they couldn’t be stopped. So, there really wasn’t much they could do in terms of making the diagnosis.
In addition, they were trained that tardive dyskinesia doesn’t have much impact on patients. But we now know, through surveys and other studies, that tardive dyskinesia can have a tremendous impact on patients and on your ability to treat the patient’s underlying mental health issues. It’s estimated that 50% of patients with tardive dyskinesia actually reduce the amount of antipsychotic medication they’re taking on their own, and about 40% may in fact stop their antipsychotic medication altogether.
Thirty-five percent of patients stopped seeing their doctor after they developed tardive dyskinesia, and about 20% of patients actually told other patients not to take their antipsychotic medication. So, tardive dyskinesia is impacting your ability to treat patients. In addition, it impacts the patients themselves. Nearly three out of four patients with tardive dyskinesia said, in surveys, that it caused severe impact on their psychosocial functioning.
It also impacted caregivers, with 70% of caregivers saying that the patients with tardive dyskinesia made them more anxious and limited them socially. So, we have this tremendous impact from tardive dyskinesia.
In addition, physicians sometimes don’t identify tardive dyskinesia correctly. They mistake it for another movement disorder: drug-induced parkinsonism. Or it falls under the rubric of extrapyramidal symptoms (EPS), and they were trained that you treat EPS with benztropine. The challenge with that is that benztropine is only indicated for acute dystonia or for drug-induced parkinsonism. It actually makes tardive dyskinesia worse. And, in the product insert for benztropine, it’s recommended that it should not be used in tardive dyskinesia. So if you have a patient whom you suspect has tardive dyskinesia, you have to discontinue the benztropine. That’s a really important first step.
And then, what else should you do? There are now two FDA-approved treatments for tardive dyskinesia. These are valbenazine and deutetrabenazine. Both of these drugs have been demonstrated in large double-blind, placebo-controlled studies to reduce tardive dyskinesia, as measured by the Abnormal Involuntary Movement Scale, by about 30%. These drugs have been demonstrated to be safe and well tolerated, with the main side effect being somnolence.
Some people can also develop parkinsonism. Why could there be Parkinsonism? This is because vesicular monoamine transporter 2 (VMAT2) inhibitors work by reducing the amount of dopamine that can be packaged in the presynaptic neuron. That means that less dopamine is available to the synapse, and this reduces movement. The American Psychiatric Association has issued guidelines for the treatment of tardive dyskinesia and has said that moderate to severe tardive dyskinesia should be treated first-line with VMAT2 inhibitors and that mild tardive dyskinesia should also be treated with VMAT2 inhibitors if the tardive dyskinesia is impacting the patient.
Given the impact that tardive dyskinesia has on patients and caregivers, and the physician’s ability to treat these patients’ mental health issues, we need to become aggressive and treat the tardive dyskinesia so that patients can improve and be able to have their movements treated without impacting their underlying mental health issues.
Daniel Kremens, professor, Department of Neurology, Sidney Kimmel Medical College, Thomas Jefferson University, codirector, Parkinson’s Disease and Movement Disorders Division, Jack and Vickie Farber Center for Neuroscience, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, has disclosed relevant financial relationships with Teva Pharmaceuticals, AbbVie, Merz, Allergan, Bial, Cerevel, Amneal, Acadia, Supernus, Adamas, Acorda, Kyowa Kirin, and Neurocrine.
A version of this article first appeared on Medscape.com.