To date, six main types of medications are available to alleviate symptoms of PD, including levodopa, dopamine agonists, inhibitors of enzymes that inactive dopamine (i.e., monoamine oxidase type B inhibitors [MAOB] and catechol-O-methyl transferase inhibitors [COMT]), anticholinergics, and amantadine (Connolly & Lang, 2014). Here, COMT is linked to Parkinson disease.