A report in the July issue of Archives of Neurology suggests that cigarette smoking is associated with a reduced risk of developing Parkinson’s disease, with long-term and current smokers at the lowest risk.

The report was based on a pooled analysis of 11 previous Parkinson’s disease studies. Involving 11,809 individuals, the studies occurred between 1960 and 2004.

Researchers also found that all tobacco products, not just cigarettes, seemed to have a risk-reducing effect on Parkinson’s disease.

There was no association, however, between Parkinson’s disease and smoking in individuals older than 75 and in Hispanic or African-American participants.

Authors of the report speculate that chemical or biomedical processes exist cigarette smoke that may exert a protective effect.