While prescribed medications are essential for managing various medical conditions, their prolonged use can sometimes lead to unintended side effects and other issues. Some of these issues can be managed and treated, while others may result in permanent damage. One such condition is Parkinson’s disease, which can be mimicked by drug-induced Parkinsonism. Certain groups of drugs can induce a set of symptoms that closely resemble those of Parkinson’s disease.
Here, we discuss those drugs and how they induce Parkinsonism.
Parkinson’s disease is a neurological condition that has affected millions of people worldwide. It typically affects the motor functions of the brain. Upon diagnosis, patients show symptoms like slowness of movement, tremor, muscle stiffness, and problems with balance and coordination. While the exact cause of the disease is still unknown, researchers have identified several genetic and environmental factors that may contribute to its development.
Besides these factors, there are certain drugs that, when used frequently, could also induce Parkinson-like symptoms. This condition is often called drug-induced Parkinsonism. This occurs primarily due to the disruption of dopamine signaling in the brain. Dopamine is a crucial neurotransmitter that helps regulate movement and coordination. When certain drugs interfere with dopamine function, it can lead to drug-induced Parkinsonism.
Here are the three main classes of drugs that are linked to drug-induced Parkinsonism.
1. Antipsychotic drugs
Antipsychotics are often used to treat conditions like schizophrenia and bipolar disorder. Examples include fluphenazine, chlorpromazine, and haloperidol. While essential for managing severe mental health conditions, these medications have been linked to an increased risk of developing Parkinsonism.
Parkinsonism usually appears days to weeks after starting antipsychotics. In some cases, the symptoms may appear several months or more. This delayed onset can make it challenging to recognize the connection between medication use and the development of movement disorders.
A recent study, published in Neurological Sciences, examined the long-term risk of degenerative Parkinsonism associated with previous use of neuroleptics. The study followed all residents in Piedmont, Northern-west Italy, older than 39 years (2,526,319 subjects) from 2013 to 2017. The study compared the risk of drug-induced Parkinsonism between 63,356 subjects exposed to antipsychotics and 316,779 unexposed subjects. A more than threefold higher risk of Parkinsonism was observed among subjects exposed to antipsychotics compared to those unexposed. The risk was higher for exposure to atypical antipsychotics than typical ones. The risk of Parkinsonism decreased after 2 years from therapy cessation but remained significantly elevated.
The study suggests that the use of antipsychotics, particularly atypical ones, is associated with a significantly higher risk of developing degenerative Parkinsonism.
2. Anti-nausea medications
Drugs like metoclopramide, prochlorperazine, and levosulpiride are commonly used to treat nausea and gastrointestinal motility disorders. They act as dopamine antagonists, meaning they block dopamine receptors in the brain, which can lead to Parkinson-like symptoms.
Numerous studies have shown that these medications can cause extrapyramidal symptoms, which are movement disorders similar to those seen in Parkinson’s disease.
A study published in The Quarterly Journal of Medicine examined how often people who took certain anti-nausea medications for the first time experienced movement problems. The study involved 2,557 patients who took metoclopramide and 2,811 patients who took prochlorperazine. There were 12 cases of acute dystonic-dyskinetic events (sudden, involuntary muscle movements) reported among those who took metoclopramide. These events were more common in people under 30 years old compared to those who were 30 years old or older. Similarly, there were eight cases of Parkinsonism reported among those who took prochlorperazine. Seven out of these eight cases were in patients over 60 years old. The study found that the risk of Parkinsonism was significantly higher in patients over 60 years compared to those under 60 years.
This study highlights that anti-nausea medications can cause movement disorders, and the risk varies depending on age. Younger people taking metoclopramide are more likely to experience sudden muscle movements, while older people taking prochlorperazine are more likely to develop Parkinsonism.
Similarly, a recent case study published in Psychiatria Danubina reported two young patients who developed dystonic reactions when they took metoclopramide. These findings underscore the importance of being aware of the potential side effects of these medications, especially in younger patients.
These studies suggest that anti-nausea medications can cause Parkinsonism, with varying risks depending on the patient’s age.
3. Antiepileptic drugs
Antiepileptic drugs are commonly prescribed to manage epilepsy and other neurological conditions. The widely used antiepileptic drugs include:
- Sodium valproate
- Gabapentin
- Pregabalin
Recent research suggests that these medications may also be associated with an increased risk of developing Parkinson’s disease.
A study published in the Journal of Brain Sciences analyzed whether prescriptions of antiepileptic drugs are significantly associated with an increased incidence of Parkinson’s disease in the German population. The study used data from German primary care practices found in the Disease Analyzer database and included all patients aged 18 years or older who were diagnosed with Parkinson’s disease between January 2010 and December 2021. Controls were patients without Parkinson’s disease, matched 1:1 by age, sex, and pre-diagnostic observation time.
The study identified 24,950 cases of Parkinson’s disease, matched with 24,950 controls (mean age 75.2 years, 47.3% women). Diagnoses of epilepsy, restless legs syndrome, and neuropathy, as well as antiepileptic drugs prescriptions, were significantly associated with an increased incidence of Parkinson’s disease. The study concluded that prescriptions of antiepileptic drugs were associated with an increased risk of subsequent Parkinson’s disease, even after adjustment for underlying diagnoses.
While further studies are needed to confirm these results, healthcare providers should be aware of this potential side effect and consider it when prescribing antiepileptic drugs, especially in patients with a history of epilepsy, restless legs syndrome, or neuropathy.
Conclusion
In conclusion, drug-induced Parkinsonism is a significant concern for patients taking certain medications, including antipsychotics, anti-nausea drugs, and antiepileptic drugs. Healthcare providers should be aware of this potential side effect and consider alternative treatments when possible, especially for patients at higher risk. Monitoring for early signs of movement disorders is crucial, even after discontinuing these medications.
