Why smokers may have a lower Parkinson's risk: It's not the nicotine

• Smoking history and exhaled carbon monoxide levels are both associated with a lower risk of developing Parkinson’s disease.
• In a new study, researchers set out to better understand this link. They found that participants who had not smoked but had high exhaled carbon monoxide levels also had lower risk of Parkinson’s disease.
• Having higher exhaled carbon monoxide levels was not linked to a lower risk of other neurodegenerative diseases.

A new study may have shed some light on the peculiar association between smoking and a lower risk of developing Parkinson’s disease.

The study, published in JAMA Neurology, reports that exposure to carbon monoxide may contribute to this link.

Parkinson’s disease is a brain condition that is growing increasingly common. The World Health Organization (WHO) estimates that its prevalence has doubled in the past 25 years.

The disease causes damage to nerve cells in an area of the brain called the substantia nigra, resulting in symptoms such as tremors and coordination problems. Some people with Parkinson’s go on to develop dementia over time.

Experts are unsure what causes Parkinson’s at present, but believe that genetic changes or environmental exposures may play a role.