Smoking is not a risk factor for sporadic amyotrophic lateral sclerosis in an Australian population.

BACKGROUND

Controversy persists as to whether smoking is a risk factor for sporadic amyotrophic lateral sclerosis (SALS), the most common form of sporadic motor neuron disease (SMND). We therefore undertook a large case-control study of smoking and SALS in Australia.

METHODS

Cases and controls were recruited Australia-wide over a 10-year period. SALS and the other subgroups of SMND were categorised on the basis of neurologists' reports. Controls were partners or friends of SMND patients or community volunteers. Individuals filled in a questionnaire regarding smoking habits. A total of 809 patients with SMND (631 with SALS) and 779 controls were included in the study. SALS males and females were analysed separately.

RESULTS

No differences between SALS patients and control groups were found with regard to (1) the odds ratios of ever-smokers, ex-smokers or current smokers compared to never-smokers, (2) the means of numbers of cigarettes per day, years of smoking, pack years or age smoking began or (3) the proportions of their parents who had ever smoked. The proportion of ever-smokers and mean pack years did not differ between the clinical subgroups of SMND or between different sites of SALS onset. Partner smoking did not increase the risk of SMND.

CONCLUSION

This Australian case-control study does not support a link between cigarette smoking and any form of SMND.