Summary: A large longitudinal study of more than 410,000 adults reveals a complex association between active cigarette smoking and neurological outcomes. Published in Neurology, the research found that people who were still smoking during follow-up had a lower measured risk of being diagnosed with Parkinson’s disease than those who quit. At the same time, quitting smoking was clearly linked with a lower overall risk of death.
The results do not prove that smoking prevents Parkinson’s disease; they show an association tied to current smoking status. Researchers stress that any apparent neurological association does not outweigh the well-established, severe harms of tobacco — including cancer, heart disease, and lung disease — and they call for studies to identify safer ways to reproduce any potential protective effects without exposure to tobacco smoke.
Key Facts
- The Parkinson’s paradox: Persistent smokers in this cohort had the lowest observed risk of Parkinson’s disease. Compared with persistent smokers, those who quit (either recently or sustained quitters) had a 60%–61% higher risk of developing Parkinson’s.
- Mortality trade-off: Despite the lower Parkinson’s rates among current smokers, quitters had lower death rates overall. Sustained quitters showed a 17% lower risk of death than persistent smokers.
- Current status matters: People who relapsed back to smoking after quitting had a Parkinson’s risk similar to persistent smokers, suggesting the association is linked to ongoing smoking rather than smoking history alone.
- Large-scale, long follow-up: The analysis followed 410,000 South Korean adults who were smokers at baseline, with an average age of 52 and an average follow-up of nine years.
- No safe level of smoking: Investigators and authors caution that these findings should not be interpreted as endorsement of smoking because its life-shortening harms are well established.
The study population included adults who reported being smokers at the start of the study and completed three health screenings over roughly four years. Based on responses about smoking frequency and timing, researchers classified participants into four groups: persistent smokers who never quit, relapsed smokers who quit during the study but later resumed smoking, recent quitters who stopped in later screenings, and sustained quitters who quit early and did not resume.
Across the follow-up period, 1,794 participants were diagnosed with Parkinson’s disease: 0.33% of persistent smokers, 0.41% of relapsed smokers, 0.67% of recent quitters, and 0.71% of sustained quitters. During follow-up there were 31,203 deaths: 7.24% of persistent smokers, 8.09% of relapsed smokers, 8.76% of recent quitters, and 7.91% of sustained quitters.
After adjusting for socioeconomic status, alcohol use, physical activity and other factors, the analysis found persistent smokers had the lowest observed Parkinson’s incidence. Recent and sustained quitters had roughly 60% greater Parkinson’s risk compared with persistent smokers, while relapsed smokers resembled persistent smokers in Parkinson’s risk. For mortality, sustained quitters had a 17% lower risk of death and recent quitters a modest 3% lower risk compared with persistent smokers; relapsed smokers had death rates similar to persistent smokers.
“The severe health risks of smoking cannot be overlooked,” said study author Jun‑Hyuk Lee, MD, PhD, of Eulji University School of Medicine in Seoul. “Although our data show a lower Parkinson’s risk among people who remained smokers during follow-up, quitting smoking produced substantial survival benefits. Quitting remains one of the most important actions for improving long-term health.”
The investigators acknowledge limitations. Smoking status was self-reported, which can introduce recall or reporting biases. The cohort was predominantly male and Korean, so findings may not apply to women or other populations. The study design cannot establish causation, and biological mechanisms behind the association remain uncertain.
Frequently Asked Questions
A: No causal proof exists. The study demonstrates an association between active smoking and lower observed Parkinson’s incidence, but it cannot prove that smoking prevents the disease. Further research is needed to identify if specific chemicals or biological pathways are responsible and whether they can be targeted safely.
A: Absolutely not. While current smokers in this study had lower Parkinson’s rates, persistent smoking was linked to higher overall mortality and well-known severe health harms. Quitting is still the best option for improving lifespan and reducing the risk of cancer, cardiovascular disease, and lung disease.
A: The biological explanation is unclear. Researchers speculate that nicotine or other tobacco compounds might influence neuronal pathways, or that differences in brain biology related to addiction risk could play a role. Scientists aim to identify any protective components and develop safe therapies that mimic beneficial effects without tobacco’s harms.
Editorial Notes
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full by the editorial team.
- Additional context was added by staff to clarify implications and limitations.
About this Parkinson’s disease research news
Author: Renee Tessman
Source: AAN
Contact: Renee Tessman – AAN
Image credit: Neuroscience News
Original research: Findings published in Neurology