Josep Maria Suelves
Researcher at the Behavioural Design Lab at the UOC eHealth Centre, member of the board of directors of the Public Health Society of Catalonia and the Balearic Islands, and vice-chairman of the National Committee for the Prevention of Smoking
The harmful effects of tobacco on health are well established. Tobacco use and exposure cause cancer and cardiovascular and respiratory diseases, which are responsible for the majority of the seven million deaths attributable to tobacco worldwide each year and the nearly 60,000 deaths that occur each year in Spain. Paradoxically, various observational studies have shown that, compared with non-smokers, smokers appear to have a lower incidence of Parkinson’s disease, although the cause of this association has not yet been clearly established.
Although some experimental studies suggest that nicotine may have protective effects on dopaminergic neurons, which might explain a certain degree of protection against Parkinson’s disease, clinical trials have not demonstrated nicotine’s efficacy in preventing this neurodegenerative disorder.
In the recently published study, the authors raised the possibility that it might be another component of tobacco smoke other than nicotine – namely carbon monoxide – that exerts a protective effect against Parkinson’s disease. To test this hypothesis, they measured carbon monoxide levels in over half a million people. After a 12-year follow-up, it was observed that people with higher-than-normal carbon monoxide levels had lower rates of Parkinson’s disease, whether they were smokers exposed to the substance via tobacco smoke or non-smokers who had been exposed via smoke emitted from traditional domestic cookstoves and fireplaces.
It is important to bear in mind that these findings do not imply any health benefit from tobacco use – given that half of regular smokers are known to die from diseases caused by such consumption – nor do they refute the serious health consequences of acute or chronic exposure to a gas as toxic as carbon monoxide. However, and despite the methodological limitations of observational studies, the results of this research provide data for further investigation into the aetiology of neurodegenerative diseases such as Parkinson’s, which may help to improve their prevention and treatment.