Jonathan Meyer, MD
Clinical Professor of Psychiatry
University of California San Diego
Chirag Shah, PharmD, RPh
Head Medical Affairs & Medical Education
The prevalence of TD is higher than commonly thought. A meta-analysis of 41 studies included over 11,000 patients with an average age of 43 years. Two-thirds of these patients were men, and more than three-quarters had a schizophrenia spectrum disorder. The overall prevalence of TD in this sample was 25%. The TD rate for those with current use of second-generation antipsychotic was lower than in those with current use of first-generation (21% vs 30%, respectively).
Various movement disorders may occur in patients with psychiatric conditions, which can lead to tardive dyskinesia (TD). However, tardive dyskinesia is often underdiagnosed or misdiagnosed. “I think there are two main reasons for underdiagnoses,” says Chirag Shah, PharmD, RPh Head of Medical Affairs & Medical Education at Neurocrine Biosciences. “The first is historical. Before approved TD medications became available, there was no truly effective way to treat this disorder. For many clinicians, it might have seemed unnecessary to diagnose a condition that could not be treated, especially in patients who were not aware of their abnormal movements (eg, patients with severe psychosis).”
Dr. Shah explains that the second reason is phenomenological because there are lot of drug-induced movement disorders (DIMDs), which can be confused with TD, such as parkinsonism. Nonmedication-related movement disorders are kept on the differential. Spontaneous dyskinesias, for example, are indistinguishable from TD and are found more commonly in older and/or edentulous patients. “Since there is no ‘test’ for TD, diagnosis depends on patient history and accurately identifying the types of abnormal movements that the patient is exhibiting,” says Dr. Shah. “This can be especially challenging in patients who have more than one DIMD, which is not uncommon, and in virtual settings in which clinicians cannot observe the patient’s entire body or are hampered by poor video/camera quality. While there are a number of factors that drive treatment decisions, but the biggest hurdle for clinicians may be misdiagnosis. “Treatments that are appropriate for one disorder may not improve—or possibly even exacerbate—another disorder,” says Dr. Shah. “That is why classifying all DIMDs as ‘extrapyramidal symptoms’ and treating them all the same can be problematic for patients; each DIMD is distinct in terms of pathophysiology, presentation, and therefore treatment.”
Other factors that may contribute to incorrect treatment, according to Dr. Shah, include lack of clinician awareness about approved TD medications, patient resistance to starting new medications, and difficulties with access (eg, approvals for reimbursement).
“Our hope is that clinicians learn to recognize and diagnose TD correctly, and then use an approved medication for treatment whenever possible. Clinicians who treat patients taking any DRBA are encouraged to seek out educational opportunities and read video-based articles that describe different DIMDs, such as the recent publication from Dr. Robert Hauser et al, which was developed through a collaborative effort between neurologists and psychiatrists who are considered TD experts,” he says.
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