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.