Could asthma drugs decrease the risk of Parkinson’s?
A recent study demonstrates that common asthma drugs decrease the formation of toxic proteins and decrease the risk of developing Parkinson’s
Parkinson’s is caused by the loss of brain cells that produce a chemical messenger called dopamine. The loss of these brain cells is associated with the abnormal processing and clumping together of a protein called alpha-synuclein, which is believed to be toxic to the dopamine-producing brain cells.
Reducing the levels of alpha-synuclein in the brain cells could prevent this clumping and slow or stop the loss of these cells. Hence, research groups have been searching for drugs that can reduce the expression of alpha-synuclein to slow down the progression of Parkinson’s.
New research finds drugs that could reduce alpha-synuclein
In this recent study, published in Science, Mittal and colleagues screened 1,126 known drugs — many of which are in currently used to treat a variety of medical conditions— in a cell model of Parkinson’s. The team aimed to identify drugs with the potential to decreased the expression of alpha-synuclein.
They found a number of drugs that activate specific proteins called beta-adrenoceptors could produce a 35% reduction in the expression of alpha-synuclein. Drugs that are known to target beta-adrenoceptors and are currently in medical use include salbutamol (also known as Ventolin), a common drug to treat asthma.
In further experiments, the researchers found that the beta-adrenoceptors activating drugs lowered the expression of alpha-synuclein in the dopamine producing cells within the brains of mice. But these drugs failed to have any effect on alpha-synuclein in mice that lack the beta-adrenoceptors — this confirms that the reduction in alpha-synuclein requires the activation of the beta-adrenoceptors.
In this study, Mittal and colleagues also demonstrated that such drugs also protected dopamine producing cells within the brain in a rodent model of Parkinson’s.
Changes in risk of Parkinson’s
Since beta-adrenoceptors activating drugs, like salbutamol, have used in medicine for a very long period of time and in a significant number patients, the research group then went onto assess whether taking such drugs influenced the risk of an individual developing Parkinson’s.
Conversely, drugs which block the activation of the beta-adrenoceptors e.g. propranolol etc. are also extensively used in medicine to mainly treat heart and blood pressure problems, hence Mittal and his research group examined whether drugs like propranolol increase the risk of developing Parkinson’s.
They examined these potential influences on risk by looking at 4.6 million individuals who had been prescribed either beta-adrenoceptors activating or blocking drugs. Interestingly, they demonstrated that in individuals who were prescribed salbutamol like drugs, there was a reduced risk of developing Parkinson’s. And there was a marked increase in risk in those individuals who were prescribed beta-adrenoceptors blocking drugs, although overall the risk of Parkinson’s was still relatively low.
A case for drug repurposing?
This is a very interesting study, which for the first time demonstrates that common anti-asthma drugs could be used to treat Parkinson’s. However, in asthma these drugs are normally inhaled into the lungs to limit their side effects. If there were to be used in Parkinson’s they would need to be taken orally so that they can get into the brain. Unfortunately beta-adrenoceptors are also found in other parts of the body, hence these types of treatment would not be without side-effects.
Additionally, for the first time an association with increased risk of developing Parkinson’s was shown with drugs that block the beta-adrenoceptors. Whilst this is an interesting finding, it does need to be replicated in other studies and at the present time we do not recommend anyone stopping taking the beta-adrenoceptors blocking drugs.
David is a member of the Research Team at Parkinson’s UK. He writes about the science behind research results. Read more posts by David, or find out more about drug repurposing in this feature article: