Responsiveness of motor and nonmotor symptoms of Parkinson disease to dopaminergic therapy

Abstract

Background The duration of clinical control of motor symptoms of Parkinson disease (PD) treated with levodopa/carbidopa preparations eventually starts to shorten, a phenomenon known as end-of-dose “wearing off.” The involvement of core nonmotor symptoms of “wearing off” (depressed mood, pain/aching, anxiety, and cloudy/slowed thinking) is not well understood. Methods A post hoc analysis from a study to validate the self-rated 9-item, Wearing-Off Questionnaire (WOQ-9), which was designed to identify motor and nonmotor symptoms of “wearing off” in PD patients, was performed to compare the frequency and sensitivity of motor and nonmotor symptoms of “wearing off” from dopaminergic therapy. Results Analysis of responses to the WOQ-9 from 216 PD patients found that individual nonmotor symptoms were reported by 25% to 50% and motor symptoms by 55% to 80% of patients. Individual nonmotor symptoms improved following the next dose of dopaminergic therapy in 43% to 53% of the patients who presented with such symptoms, whereas motor symptoms improved in 48% to 66% of the cases, suggesting both types of symptoms respond to dopaminergic therapies. Conclusion Nonmotor symptoms of PD appear sensitive to dopaminergic treatment. These symptoms resemble those seen with depressive, anxiety, and somatoform disorders suggesting potential shared mechanisms as well as possible treatment implications.