What if a gas usually known for being dangerous could also give scientists a new clue about Parkinson’s disease?
For years, researchers have noticed something puzzling: cigarette smoking has been associated with a lower risk of Parkinson’s disease (PD). But nicotine does not seem to explain the connection. In a previous randomized trial, nicotine treatment did not slow the progression of early Parkinson’s disease.
A new large observational study suggests that carbon monoxide (CO) may be part of the puzzle. Researchers analyzed data from 512,701 adults who had their smoking history recorded and their exhaled CO levels measured. After a median follow-up of about 12 years, 1,131 participants developed Parkinson’s disease.
Interestingly, higher levels of exhaled CO were associated with a lower risk of Parkinson’s disease not only among smokers, but also among people who had never smoked. Among never-smokers, those with the highest CO levels were associated with a 35% lower risk of Parkinson’s disease compared with those with the lowest levels.
But there is an important catch: this does not mean that carbon monoxide prevents Parkinson’s disease, or that smoking is healthy. The study was observational, so it can show an association but cannot prove that CO causes the lower risk. Smoking was also linked to higher risks of lung cancer, heart disease, stroke, and death from any cause.
Scientists now need to reproduce these findings in other groups and understand how CO might interact with Parkinson’s disease. A clinical trial is already investigating whether carefully controlled, low-dose CO could have potential effects in people with Parkinson’s disease.
Sometimes, the most interesting scientific discoveries begin with a mystery — but solving it takes more research.
Source: Medscape Medical News
