To the Editor We read with interest the article by Savica et al,1 who described an increase in the incidence rate of parkinsonism in the Rochester Epidemiology Project between 1976 and 2005. This finding contradicts our recently reported observation that the incidence rate of parkinsonism was lower in a subcohort of the Rotterdam Study that was followed up between 2000 and 2011 compared with a subcohort that was followed up between 1990 and 2000.2 Similarly, a UK primary care study previously reported a significant decline in Parkinson disease (PD) incidence rates between 1999 and 2009.3