Pilot Deprescribing of Antimuscarinic Overactive Bladder Medications in Parkinson Disease

This is an unblinded, non-randomized National Institute of Health (NIH) Stage I of Behavioral Intervention Development trial. The investigators will enroll 20 subjects with Parkinson disease (PD) for a series of 20 of N-of-1 trials. The investigators will use a single-arm crossover titration/reversal design ("ON" \[A\] vs. "OFF" \[B\]) with up to 4 periods. All participants will follow the sequence ABAB. Each period will last up to 10 weeks, allowing for sufficient time for up-titration and onset of drug action, and down-titration and washout. Each participant will have the option to participate in less (2-3) or more (3-4) periods depending on whether additional information is needed to make an informed decision about continuing or discontinuing the overactive bladder (OAB) antimuscarinic at the end of the study. The intervention drug will be an OAB antimuscarinic, previously prescribed to the participants by their physician. The investigators will reduce the dose of each OAB antimuscarinic by 25-50% every 1-2 weeks during the "OFF" \[B\] period, with the goal to completely discontinue the medication.