Ana Isabel Rodríguez Pérez

Various studies have shown that smokers have a lower risk of developing Parkinson’s disease, but the causes remain unknown. A study has analysed the role played by carbon monoxide — a toxic gas produced by the combustion of tobacco — in this association. To this end, the team conducted a twelve-year follow-up study of more than half a million adults in China. The results show that regular smoking was associated with an increased risk of lung cancer, ischaemic heart disease, stroke and all-cause mortality, but with a lower risk of Parkinson’s disease. Most strikingly, amongst people who had never smoked, higher levels of exhaled carbon monoxide—which the authors measured—were associated with a lower risk of Parkinson’s disease. According to the study, published in JAMA Neurology, these findings demonstrate a possible protective role of carbon monoxide in the disease, rather than smoking itself.

A Danish study published in JAMA Neurology found an association between long-term exposure to residential road traffic noise and an increased risk of developing Parkinson's disease. The study followed more than three million Danish adults aged 40 years and older for 18 years using data from Denmark's national administrative and health registries. The researchers assessed residential road traffic noise exposure at both the most exposed and the least exposed façades of participants' homes. The study also found that individuals with a quiet façade had a lower risk of developing Parkinson's disease than those whose homes were exposed to high levels of noise on all sides.