- This study found an inverse association of current tobacco smoking with the risk of Parkinson’s disease (PD).
- The protective effect of smoking was attenuated with increasing duration of time since quitting smoking.
Why this matters
- Findings warrant further efforts to determine the biological mechanisms underlying the inverse association between tobacco smoking and PD for a better understanding of PD aetiology.
- This study compared the risks of mortality from PD with smoking in 29,737 male doctors in the British Doctors cohort study in 1951 and in survivors who were resurveyed about changes in their smoking habits on 6 successive occasions between 1958 and 1998.
- Funding: The Medical Research Council.
- In doctors aged 65–69 years, the prevalence of current smoking declined progressively from 67% in 1951 to 8% in 1998.
- The crude mortality rate from PD was reduced in current vs non-smokers (30 vs 46 per 100,000 person-years).
- In the baseline model, current vs never smokers in 1951 had a 29% lower risk of PD (relative risk [RR], 0.71; 95% CI, 0.60-0.84).
- In the updated model, current vs never smokers had a 40% lower risk of PD (RR 0.60; 95% CI, 0.46–0.77).
- Adjusting for age at risk, the risk of PD was inversely associated with the amount of tobacco smoking in both the baseline (P=.0006) and updated (P=.002) models.
- The protective effect of current smoking vs never smoking on the risk of PD was attenuated by increasing duration since quitting.
- 0–9 years (RR, 0.71; 95% CI, 0.54-0.93),
- ≥10 (RR, 0.86; 95% CI, 0.70-1.06).
- Analysis was based on only 283 cases of PD.