ADORA2A and Parkinson disease: Moreover, it has been reported that the expression level of A2ARs is altered in the striatum of PD patients (Mishina et al., 2011; Ramlackhansingh et al., 2011), which may change the activity of striatal A2AR neurons (Gerfen et al., 1990; Mitchell et al., 1989), thus contributing to sleep disturbances in PD patients.