A large new study of smokers suggests a complex relationship between smoking behaviour, Parkinson’s disease, and mortality. Researchers found that people who were currently smoking had a lower risk of developing Parkinson’s disease, while those who quit smoking experienced a lower risk of death. The findings were published on 25 February 2026 in Neurology®, the medical journal of the American Academy of Neurology. Importantly, the study does not establish that smoking prevents Parkinson’s disease; rather, it identifies an association that warrants further investigation.
Study author Jun-Hyuk Lee, MD, PhD, of Eulji University School of Medicine in Seoul, South Korea, emphasised that the well-established harms of smoking remain substantial. Smoking continues to be a leading cause of preventable death worldwide and is strongly linked to serious conditions such as heart disease, cancer, and chronic respiratory illness. While the study observed that individuals who quit smoking had a higher risk of Parkinson’s disease compared to those who continued smoking, it also demonstrated that quitting was associated with a meaningful reduction in mortality risk. The overall health benefits of cessation, therefore, remain clear and compelling.
The research followed more than 410,000 adults in South Korea who were all smokers at baseline, with an average age of 52 years. Participants were tracked for approximately nine years. Throughout the study period, they underwent repeated health screenings—initially at baseline, then roughly two years later, and again after another two years. At each point, participants reported their smoking habits, including frequency and quantity, allowing researchers to examine changes in smoking behaviour over time.
Based on these patterns, participants were categorised into four groups: persistent smokers who never quit, relapsed smokers who initially quit but later resumed smoking, recent quitters who stopped after several years, and sustained quitters who quit early and remained smoke-free. Over the course of the study, 1,794 individuals developed Parkinson’s disease. The incidence was lowest among persistent smokers (0.33%) and relapsed smokers (0.41%), and higher among recent quitters (0.67%) and sustained quitters (0.71%).
A total of 31,203 participants died during follow-up. Mortality rates varied modestly across groups: 7.24% among persistent smokers, 8.09% among relapsed smokers, 8.76% among recent quitters, and 7.91% among sustained quitters. After adjusting for factors such as income, alcohol consumption, and physical activity, researchers found that persistent smokers had the lowest risk of Parkinson’s disease. In contrast, both recent and sustained quitters had a 60% to 61% higher risk compared to persistent smokers, while relapsed smokers had a similar risk to those who continued smoking.
When examining mortality outcomes, however, a different pattern emerged. Sustained quitters had a 17% lower risk of death compared to persistent smokers, and recent quitters had a modest 3% reduction. Relapsed smokers showed no difference in mortality risk relative to persistent smokers. The researchers concluded that while current smoking status appears linked to Parkinson’s risk, quitting smoking offers clear survival benefits. They also noted limitations, including reliance on self-reported data and a study population largely composed of Korean men, which may limit broader generalisability.
More information: Sung-Ho Ahn et al, Dynamic Smoking Patterns and Risk of Parkinson Disease and All-Cause Mortality A Competing Risk Analysis Approach, Neurology. DOI: 10.1212/WNL.0000000000214651
Journal information: Neurology Provided by American Academy of Neurology
