The beta-2 adrenoreceptor is a regulator of the alpha-synuclein gene, and it has been hypothesized that beta-2 adrenoreceptor antagonists increase expression of alpha-synuclein, thus promoting the development of PD, while beta-2 adrenoreceptor agonists decrease this expression and are thus protective [8]. This evidence concerns the gene ADRB2 and Parkinson disease.