DRD1 and Parkinson disease: GPCR positive allosteric modulators (PAMs) have been proposed to provide unique advantages over orthosteric agonists including greater receptor subtype selectivity, saturable therapeutic effects and the ability to maintain spatial and temporal patterns of endogenous dopamine signaling, which collectively may lead to reduced side effects.3,4 Multiple groups have reported that DRD1 PAMs, such as LY3154207, CID2886111, and DETQ, stimulate DRD1 signaling.5,6 With ongoing clinical investigation, DRD1 PAMs may offer new therapeutic opportunities for PD.3,7