DDC and Parkinson disease: This possibility is supported bythe results of Nagatsu and Sawada (2007), who found that the activitiesand/or mRNA and protein levels of AADC and other enzymes are reducedin the brains of human PD patients.45 Similarly,Tehranian et al. (2006) observed inhibition of AAAD enzyme activityin dopaminergic cells overexpressing alpha-synuclein.46 The authors attributed this effect to interactions betweenAADC and α-synuclein, which forms in Lewy bodies and Lewy neuritesduring PD.