Propranolol Reduces Parkinson's Tremor and Inhibits Tremor-Related Activity in the Motor Cortex: A Placebo-Controlled Crossover Trial

Parkinson’s disease tremors are caused by overactive brain circuits, including those in the motor cortex, cerebellum, and thalamus. These tremors often worsen during stress, likely due to the activation of the body’s stress-response system. A recent study investigated whether propranolol, a medication commonly used to lower blood pressure and heart rate, could reduce tremors in people with Parkinson’s during both rest and stressful situations. In the study, 27 participants with Parkinson’s received either a single dose of propranolol or a placebo on two different days. Tremor severity was measured using accelerometry, and brain activity was assessed with functional MRI during tasks designed to create stress. The results showed that propranolol significantly reduced tremor severity across all situations—whether the participants were at rest or under stress. The medication worked by reducing activity in the motor cortex, a critical area for movement control, while its effects on other brain regions like the cerebellum and thalamus were less pronounced. Interestingly, the tremor-reducing effect of propranolol was not specific to stress-induced tremors. It also helped with resting tremors, suggesting that propranolol has a general calming effect on the brain’s motor circuits. These findings highlight propranolol’s potential as an additional treatment for Parkinson’s tremors, especially for those that don’t respond well to standard dopamine-based therapies. Researchers believe propranolol’s effects may be tied to its action on beta-1 receptors in the motor cortex, opening the door for more targeted treatments with fewer side effects. This study also suggests that managing the body’s stress-response system, through medications like propranolol or behavioral approaches like mindfulness, could play a key role in improving life for people with Parkinson’s disease.