By George Omagbemi
Several studies have identified a surprising and consistent association between cigarette smoking and a lower risk of developing Parkinson’s disease, prompting scientists to investigate why smokers appear to be less likely to develop the neurodegenerative disorder.
The relationship has been observed for decades and is considered one of the stronger environmental associations reported in Parkinson’s disease research. However, scientists stress that the finding is an association, not proof that smoking protects against Parkinson’s disease.
Researchers have proposed several possible explanations. One is nicotine, which interacts with the brain’s nicotinic acetylcholine receptors and can influence dopamine signalling. Other chemicals present in tobacco smoke, including carbon monoxide and compounds that affect monoamine oxidase, have also been investigated as possible contributors.
Recent research continues to examine the mystery. A 2026 report discussed evidence suggesting that smoking was associated with about a 30 per cent lower risk of Parkinson’s disease, with the researchers examining whether carbon monoxide may partly explain the relationship.
There is also an important scientific complication known as reverse causation. Some researchers have suggested that biological changes occurring before Parkinson’s symptoms become obvious could make people less likely to smoke or more likely to quit, potentially contributing to the observed association.
What remains clear is that the finding should not be interpreted as a recommendation to smoke. Cigarette smoking is firmly established as a major cause of serious diseases and premature death, while no tobacco product has been established as a safe preventive treatment for Parkinson’s disease.
Scientists are instead interested in understanding which biological mechanisms may be responsible for the association, because identifying them could potentially point toward safer approaches for preventing or treating Parkinson’s disease.
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