Cigarette smoking linked to Lou Gehrig's disease

Smoking cigarettes may increase the risk of developing the rare muscle-wasting disease amyotrophic lateral sclerosis, or ALS, according to a study published in this month's issue of Archives of Neurology.

Researchers, led by Dr. Hao Wang at the Harvard School of Public Health, found that current smokers had a 42 percent increased risk of developing the disease and former smokers had a 44 percent increased risk.

The longer people smoked and the more cigarettes they smoked per day increased the risk, the study found.

Previous studies have suggested that smoking may be a risk factor for ALS, also known as Lou Gehrig's disease, but they involved a small number of participants or were conflicting. This study analyzed data from five different long-term studies involving more than 1 million people, 832 of whom developed ALS.

The risk of developing ALS might be caused by damage to neurons from nitric oxide or other components of cigarette smoke (such as pesticide residue), the authors wrote. Chemicals in cigarette smoke also generate free radicals and by-products such as formaldehyde that are associated with the disease.