Behavioral and/or Mirabegron to Treat Urinary Symptoms in Parkinson Disease

While Parkinson's Disease (PD) is often characterized by the motor symptoms of the disease (tremor, bradykinesia, rigidity), non-motor symptoms such as urinary symptoms correlate more closely with impaired well-being as the disease progresses. The urinary symptoms of overactive bladder (OAB), including urgency, frequency, and nocturia, with or without urinary incontinence, are the most common urinary symptoms of PD. Because OAB symptoms, such as incontinence and nocturia, are associated with falls (a cause of increased mortality in PD), spouse/caregiver stress, and, ultimately institutionalization, it is critical that the investigators optimize the care of urinary symptoms for Veterans with PD. In the non-PD population, pelvic floor muscle contractions diminish bladder muscle contraction and recent evidence demonstrates that behavioral training with pelvic floor muscle exercises improves the cortical integration of bladder afferent signals. Because of its effectiveness compared to drugs, pelvic floor muscle exercise-based behavioral therapy is recommended first-line in men and women without PD who have OAB. Pelvic floor muscle exercise-based behavioral therapy for urinary symptoms requires individuals to learn a motor skill and implement an adaptive behavioral strategy incorporating pelvic floor muscle contraction to delay the need to void when urgency strikes. The PI's research group demonstrated the feasibility and preliminary efficacy of pelvic floor muscle exercise-based behavioral therapy to treat urgency incontinence in adults with PD. However, the most recent clinical guidelines for the treatment of urinary symptoms in PD recommend treatment with anticholinergic drugs and mention the potential option for noradrenergic bladder relaxants. While some anticholinergic drugs are effective in reducing symptoms of OAB, it is important to note that there is a glaring lack of an empirical evidence base to promote these drugs in the setting of PD given that they add to the anticholinergic burden of antiparkinsonian therapy and may worsen the cognitive and autonomic burdens of the illness. Noradrenergic bladder relaxants may have a more favorable side effect profile; however, the evidence for efficacy in PD is minimal. Therefore, randomized controlled trials (RCTs) are needed to optimize treatment paradigms for urinary symptoms in PD. The investigators' preliminary studies suggest adults with PD and mild cognitive dysfunction can successfully implement behavioral therapy for urinary symptoms. However, in the investigators' most recent VA-funded, multisite trial, 50% of participants reported a clinically significant reduction in urinary symptoms after treatment with either behavioral or drug treatment. Additional research using a Sequential Multiple Assignment Randomized Trial (SMART) design offers an efficient strategy to understand both intervention and patient factors that will inform an individualized treatment plan. With a SMART design, Aim 1 will determine if non-responders to behavioral or drug treatment (expected to be 50% of population) demonstrate a clinically significant response to combination behavior and drug treatment compared to a single treatment approach. In Aim 2, the investigators will determine patient factors that influence optimized treatment of urinary symptoms in Veterans with PD.