Medications for lung disorders not linked to Parkinson’s risk in study
Results in Finland contrast with earlier studies of the inhaled medicines
A history of using inhaled beta-2 adrenoceptor (B2AR) agonists to treat asthma or chronic obstructive pulmonary disorder (COPD) was not associated with a decreased risk of developing Parkinson’s disease, according to a recent Finnish study.
The findings contrast earlier epidemiological studies that found these medications, commonly used to treat lung conditions like asthma or COPD, were associated with a lower risk of developing the neurodegenerative disease.
While some patients with both COPD and asthma who had high levels of exposure to the medications appeared to be at a lower risk, researchers believe the relationship could be explained by other factors, such as lung disease severity and smoking history.
B2AR agonists are bronchodilators, meaning they relax the muscles in the lungs and widen the airways to make breathing easier.
Preclinical studies found that these medications lowered levels of alpha-synuclein — the protein that toxically accumulates in nerve cells in Parkinson’s disease — in animal and cell models.
Moreover, a handful of epidemiological studies suggested that use of B2AR agonists are associated with a lower risk of developing Parkinson’s.
Still, the potential relationship is under debate. Previous studies failed to account for certain factors, like smoking history, that can influence the need for beta-2 agonists, as well as Parkinson’s risk. Smoking is the strongest known risk factor for COPD, but it has been linked to a lower risk of Parkinson’s.
The Finnish study
Now, the researchers examined the potential association between B2AR agonist use and Parkinson’s risk among people living in Finland.
They used information from FINPARK, a study involving 22,189 Finnish residents with Parkinson’s disease and a matched comparison group without Parkinson’s, as well as linked health information contained in other Finnish health registries.
To minimize the effects of certain confounding factors, the analysis was limited to patients with a history of asthma or COPD more than three years before their Parkinson’s diagnosis, yielding a total of 1,406 people.
Each Parkinson’s patient was then matched with up to seven controls without Parkinson’s in terms of several factors, including age, sex, and COPD or asthma history. That total was 8,630 people.
The mean age in both groups was about 73, and 51% were men. People with asthma/COPD had lived with at least one of the conditions for a median of 12.4-12.9 years. Most people (more than 74%) had only asthma, about 15% had both conditions, and fewer than 10% had only COPD.
The two groups had similar distributions of coexisting conditions, the most common of which were cardiovascular diseases.
Inhaled B2AR agonist use was common in both groups. More than 83% had a history of purchasing short-acting medications, and just over 48% had purchased long-acting ones.
Neither type of the medication was overall associated with the risk of Parkinson’s, even when controlling for factors such as cardiovascular disease, age, sex, use of certain other medications, or duration of asthma/COPD.
The degree of exposure to the medications was not consistently associated with the chance of having Parkinson’s, meaning that purchasing more or less of the medicine didn’t necessarily affect a person’s risk.
An exception was among patients who had high annual exposure to long-acting B2AR agonists, specifically those in the top 25% of such cases, who were found to be at a decreased risk of Parkinson’s in additional analyses.
That relationship was further modified by lung disease type, with the lowest risk observed among those with both asthma and COPD.
Study limitations and conclusions
“This might suggest that regular and long-term use of long-acting B2AR agonists is more common among those with more severe disease such as persons with both asthma and COPD,” the researchers wrote.
Still, “the protective association might be confounded by lifestyle factors such as smoking.”
They noted that the registry-based study limited their ability to assess these potentially influential factors, including smoking status or patients’ lung disease severity.
Nevertheless, the study overall indicates that “inhaled B2AR agonists were not associated with a risk of [Parkinson’s disease] among persons with asthma/COPD,” the researchers wrote.
The study’s design and methods make it difficult to compare its findings to earlier studies, some of which saw a relationship and some that did not, the team noted.
The study was funded by the Michael J. Fox Foundation for Parkinson’s Research and the Finnish Parkinson Foundation.