Statins and amyotrophic lateral sclerosis--the level of evidence for an association.

Myopathy is a known side effect of statins, but neurotoxicity is not. Two studies reported that statins and amyotrophic lateral sclerosis (ALS) appear together more than expected amongst adverse events in overlapping surveillance databases. A pooled analysis of clinical trials, many with short follow-up, showed no higher rate of ALS in the statins arms. In older age groups, statin use increased from approximately 5% in 1991 to approximately 40% in 1998 and then remained constant. There was no similar increase in ALS incidence. The initial signals of a strong association from drug surveillance systems should now be discounted, but not disregarded.