The correct answer is B.
Several epidemiological studies have suggested that caffeine consumption may be associated with significantly decreased risk for Parkinson disease (PD). A meta-analysis of 173 studies about early nonmotor symptoms of PD found that the risk of PD was 33% lower among coffee drinkers (OR 0.67).1 While the mechanism remains unclear, some scientists have proposed that a neuroprotective effect may be involved. However, research cannot rule out reverse causality (for example, prodromal PD symptoms may decrease the use of caffeine), symptomatic benefit (for example, the possibility that caffeine may improve motor symptoms and delay PD diagnosis), or other factors that may be involved.
Question 2 (Answer and Question 3 on Next Page>)
1. Noyce AJ, Bestwick JP, Silveira-Moriyama L, et al. Meta-analysis of early nonmotor features and risk factors for Parkinson disease. Ann Neurol. 2012;72:893-901.
2. Postuma RB, Anang J, Pelletier A, et al. Caffeine as symptomatic treatment for Parkinson disease (Café-PD): A randomized trial. Neurology. 2017;89:1795-1803.
3. Postuma RB, Anang AE, Munhoz RP, et al. Caffeine for treatment of Parkinson disease: a randomized controlled trial. Neurology. 2012;79:651-658.