If the epidemiological association of smoking and Parkinson disease (PD) is causal, projecting future cases without considering smoking may underestimate disease burden, underscoring the urgency of adequate resource allocation, a recent study found. The age- and gender-stratified smoking prevalence in the US from 2000 to 2040 were obtained from the US Census Bureau and the US Surgeon General's Smoking Report. PD prevalence was estimated based on population aging with and without an account of the impact of declining smoking rates. Relative risks of 0.56 and 0.78 were applied for current and former smokers, respectively. Researchers found:

• Accounting for aging alone, ∼700,000 PD cases are predicted by 2040.
• After accounting for the declining smoking prevalence, ∼770,000 cases, an increase of ∼10% over the estimate without smoking, is predicted.