Drug therapies targeting the motor features of Parkinson’s disease act by potentiating dopamine signaling, involving the direct implementation of the neurotransmitter dopamine (e.g., levodopa), monoamine oxidase (MAO) enzyme inhibition (e.g., selegiline), and catechol-o-methyltransferase (COMT) inhibition (e.g., entacapone). Here, COMT is linked to Parkinson disease.