Antipsychotic drugs used to treat patients with psychotic (eg, schizophrenia) and mood (eg, bipolar disorder and major depressive disorder) disorders can cause abnormal involuntary movements. Historically, the term “extrapyramidal symptoms (EPS)” has been used broadly in psychiatry and product labeling to refer to all these drug-induced movements. As a result, it is well entrenched in the psychiatry lexicon.
However, it is now widely recognized that drug-induced movement disorders (DIMDs), which include tardive dyskinesia (TD), drug-induced parkinsonism (DIP), akathisia, and dystonia, are distinct conditions with specific symptoms, different underlying mechanisms, and subsequently different treatment approaches. As a result, the broad use of EPS to describe any DIMD is inadequate and can lead to poor outcomes for patients.
For instance, TD and DIP are common DIMDs, but they are quite distinct from each other. TD is characterized by an excess of movements that are irregular, jerky, and unpredictable. On the other hand, parkinsonism is characterized by a paucity or slowness of movement and may be accompanied by rigidity. When involuntary abnormal movements occur, they are typically rhythmic (ie, tremors). It is critically important to differentiate between DIP and TD because treatment approaches for these movement disorders are different. Anticholinergics are indicated to treat DIP, but they can worsen TD. Because of this, failure to differentiate TD from DIP can result in inappropriate treatment.
The American Psychiatric Association (APA) treatment guidelines and Diagnostic and Statistical Manual of Mental Disorders, 5th ed, Text Revision (DSM-5-TR) warn that anticholinergics, such as benztropine, should not be used in patients with TD because they can worsen symptoms. Instead, the APA recommends vesicular monoamine transporter 2 (VMAT2) inhibitors, the only FDA-approved treatment, as first-line treatment for TD that has an impact on the patient, regardless of severity of movements.
This case study features James, a 55-year-old man who was prescribed a long-acting injectable (LAI) typical antipsychotic to treat schizophrenia. Following the development of abnormal finger movements, James was diagnosed with EPS and initiated on benztropine, a commonly prescribed anticholinergic. When his symptoms worsened, James was reevaluated and diagnosed with TD. After gradual discontinuation of benztropine, he was prescribed a VMAT2 inhibitor.
James’s case highlights the importance of differentiating TD from other DIMDs and the consequences of using anticholinergic medication to treat a patient with TD.
Not an actual patient.
James, a 55-year-old man with schizophrenia and a misdiagnosis of EPS
James is 55 years old, lives independently, and receives care at a community mental health center (CMHC). He was diagnosed with schizophrenia at the age of 24 and is supported by a local Assertive Community Treatment team. For many years, he had been treated with an LAI typical antipsychotic.
The case manager at the CMHC noticed that James had developed some abnormal, involuntary finger movements and suggested he mention these to his clinician at his next psychiatric appointment. After examination, James’s clinician diagnosed the abnormal movements as EPS. James was initiated on benztropine at 1 mg and titrated up to 2 mg twice daily. During this time, the finger movements persisted, and James began to experience involuntary grimacing.
The worsening of James’s symptoms while on anticholinergic treatment prompted his clinician to reassess his diagnosis.
James’s abnormal movements
Originally started after long-term exposure to a typical antipsychotic medication
Worsened with anticholinergic treatment
Were irregular and jerky, affecting his fingers and face
Based on these symptoms, which are consistent with the DSM-5-TR criteria, James's clinician diagnosed him with TD and then used the Abnormal Involuntary Movement Scale (AIMS) to assess the severity of his movements.
The clinician then asked James about how the movements impacted his day-to-day life. James reported that he felt lonely, like people were avoiding him because of his TD movements. He also had some difficulty holding objects, like a spoon or his toothbrush, because of the finger movements, which made it challenging to perform some routine activities.
To manage James’s TD, the clinician took the following approach:
| 1. | James was switched from a typical to an atypical antipsychotic, which may have less propensity to cause abnormal movements. His schizophrenia symptoms remained stable, but his TD persisted |
| 2. | Benztropine dose was gradually reduced over 1 to 4 months from 2 mg twice a day (BID) to 1 mg BID and then discontinued |
| 3. | James was started on a VMAT2 inhibitor, the only FDA-approved treatment for TD. The APA recommends VMAT2 inhibitors as first-line treatment for TD that has an impact on the patient, regardless of movement severity |
Once on the VMAT2 inhibitor, James experienced reduced jerky finger movements and facial grimacing. With a reduction in movements, he was able to eat with utensils and brush his teeth with less difficulty.
James’s initial diagnosis of EPS and treatment with anticholinergics worsened his TD movements
An accurate diagnosis of TD helped James get appropriate treatment
Anticholinergics, such as benztropine, should not be used to treat or prevent TD
The APA recommends that TD symptoms that have an impact on the patient, regardless of severity, should be managed with a VMAT2 inhibitor
James’s case study highlights the consequences of failing to differentiate and accurately diagnose TD and using an anticholinergic, like benztropine, to treat patients with TD
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