Treatment of Spinal Cord Injury Patients for Neurogenic Bladder: Anticholinergic Agent vs. Mirabegron

Inclusion Criteria: 1. Both genders with spinal cord injury being treated for neurogenic bladder and age \>60 years 2. All ethnic groups 3. Veterans will be enrolled to allow mailing of study medication by VA pharmacies. 4. Laboratory results: Normal clinical labs for CBC (complete blood count), CMP (comprehensive metabolic panel), and UA (urinalysis) within past 6 months or repeat at screening if none. For example: HCT (hematocrit) ≥34%, GFR (glomerular filtration rate) ≥ 30 mL/min, liver enzymes (AST (aspartate aminotransferase test) \< 2 x upper limit of normal, ALT (alanine aminotransferase test) \< 2 x upper limit of normal, alkaline phosphatase \< 2 X upper limit of normal), normal electrolytes, urinalysis and asymptomatic for UTI (urinary tract infection) 5. Taking a minimum regimen for 3 months of anticholinergic agent. Exclusion Criteria: 1. Diagnosis of dementia or cognitive impairment from another condition such as TBI (traumatic brain injury), ALZ (alzheimers), Lewy body dementia or vascular dementia 2. End stage renal disease (GFR \<30) or bladder obstruction 3. Poorly controlled blood pressure (BP), systolic BP\>180, diastolic BP\>110 mmHg) 4. Renal function - exclude if serum creatinine \>2x normal range 5. Liver function - exclude if \>2x normal liver enzyme levels 6. History of, or currently active treatment for cardiac dysrhythmias, including atrial fibrillation (eg. apixaban. If subject is currently taking metoprolol they will be monitored and dose may need to be adjusted on mirabegron) 7. Current treatment with desipramine, digoxin 8. Active/unstable conditions: inflammatory, thyroid, autoimmune, gastrointestinal (GI), hematologic, or neoplastic disorders. Exclude subjects with clinical lab values outside the normal range (other than as specified above). 9. Subject is considered unsuitable for the study in the opinion of the investigator for any other reason