Underactive and overactive bladders are related to motor function and quality of life in Parkinson's disease

Overactive bladder occurs in up to 70 % and underactive bladder in up to 50 % of patients with Parkinson's disease (PD), which is thought to reflect an altered frontal-basal ganglia circuit. However, it is not clear how bladder disorder is related to motor function and to quality of life (QOL) in PD. We studied these relationships by conducting multiple regression (MR) and bivariate correlation (BV) statistical analyses. We recruited 58 PD patients, irrespective of the presence of bladder disorder: 35 men and 23 women of mean age 66.8 years, mean duration of the disease 5.4 years, and median score of Hoehn-Yahr stage 3. We administered a bladder questionnaire including two major types of lower urinary tract symptoms, 'overactive bladder (OAB)' and 'voiding difficulty,' in addition to a QOL index and a pressure-flow urodynamic study to detect detrusor overactivity (DO) during filling; and detrusor weakness, outlet obstruction, and post-void residuals (PVR) during voiding. We analyzed the results using the MR and BV methods. (1) Motor impairment (by HY grades) was significantly related to detrusor weakness (P < 0.05 MR); voiding difficulty, OAB (P < 0.05 BV) (by de novo, levodopa honeymoon, and wearing-off); and voiding difficulty (P < 0.05 MR). (2) Bladder QOL was significantly related to OAB, increased bladder sensation (P < 0.05 MR) and voiding difficulty (P < 0.05 BV). (3) Male gender was significantly related to outlet obstruction, DO (P < 0.05 MR). (4) Age was significantly related to DO and PVR (P < 0.05 MR). Disease duration was significantly related to OAB (P < 0.05 MR). From these results, detrusor weakness (relevant to motor impairment) and OAB (relevant to bladder QOL) are thought to be fundamental in PD. In contrast to the mechanism of OAB, the mechanism of detrusor weakness in PD remains unclear and warrants further exploration.