Impact of Acute Dopamine Replacement on Cognitive Function in Parkinson's Disease

Background PD causes striatal dopaminergic denervation in a posterior/dorsal to anterior/ventral gradient, leaving motor and associative cortico‐striato‐pallido‐thalamic loops differentially susceptible to hyperdopaminergic effects with treatment. As the choice and titration of symptomatic PD medications are guided primarily by motor symptoms, it is important to understand their cognitive implications. Objective To investigate the effects of acute dopaminergic medication administration on executive function in Parkinson's disease (PD). Methods Participants with idiopathic PD were administered the oral Symbol Digit Modalities Test (SDMT; n = 181) and the Stroop test (n = 172) in the off‐medication and “best on” medication states. ANCOVA was used to test for differences between off‐medication and on‐medication scores corrected for age and years of education. Results After administration of symptomatic medications, scores worsened on the SDMT (F = 11.70, P