Can metoprolol (beta blocker) cause Parkinson's disease?

Metoprolol and Parkinson's Disease Risk

There is no strong evidence that metoprolol causes Parkinson's disease. The current medical literature does not establish a causal relationship between metoprolol use and the development of Parkinson's disease.

Evidence on Beta-Blockers and Parkinson's Disease

• An observational study reported a potential link between the chronic use of propranolol (a non-selective beta-blocker) and an increased risk of Parkinson's disease, but this association is likely due to reverse causation rather than a true causal relationship 1
• The apparent association may be explained by the fact that prodromal Parkinson's disease often presents with non-specific action tremor, which is commonly treated with beta-blockers like propranolol 1
• Even if a causal relationship existed, the estimated risk would be very small - approximately one case in 10,000 patients after 5 years of propranolol use, which would be considered a very rare adverse effect 1
• Metoprolol is a cardioselective (beta-1 selective) beta-blocker, which has a different pharmacological profile than non-selective beta-blockers like propranolol 2

Beta-Blockers in Neurological Conditions

• Beta-blockers are actually used therapeutically in some movement disorders, including essential tremor 2
• In patients with existing Parkinson's disease, low-dose propranolol has been shown to improve levodopa-induced dyskinesia by approximately 40% without increasing parkinsonian motor disability 3
• A Cochrane review examining beta-blocker therapy for tremor in Parkinson's disease found insufficient evidence to determine whether beta-blockers are effective and safe for treating tremor in Parkinson's disease patients 4

Metoprolol's Safety Profile

• The most common adverse effects of metoprolol include hypotension, bronchospasm, bradycardia, and worsening heart failure in patients with pre-existing ventricular dysfunction 2
• Metoprolol's precautions and contraindications include AV block greater than first degree, SA node dysfunction, decompensated systolic heart failure, hypotension, and reactive airway disease 2
• Neurological side effects are not prominently featured in metoprolol's established adverse effect profile 2

Clinical Implications

• When prescribing metoprolol, clinicians should monitor blood pressure and heart rate at each visit, with a target resting heart rate of 50-60 beats per minute unless limiting side effects occur 5
• Signs of worsening heart failure or bronchospasm should be monitored, particularly during initiation and with IV administration 5
• The risk of developing Parkinson's disease should not be a major consideration when deciding whether to prescribe metoprolol for appropriate indications such as hypertension, angina, heart failure, or arrhythmias 1

In conclusion, patients and healthcare providers should not avoid using metoprolol due to concerns about Parkinson's disease risk when the medication is indicated for cardiovascular conditions.