The non-motor symptom complex of Parkinson's disease: a comprehensive assessment is essential.

Parkinson's disease (PD) is a progressive disease that usually affects the motor system but is also associated with a non-motor symptom (NMS) complex that ranges from dribbling saliva, constipation, depression, sleep disorders, apathy, hallucinations, and dementia. These features contribute significantly to morbidity and institutionalization, more than quadrupling the cost of care. Furthermore, recent evidence suggests that NMS such as constipation, olfaction, rapid eye movement behavior disorder, fatigue, and depression may be markers of a preclinical stage of PD. PD-NMS are not well recognized in clinical practice and part of the reason is the lack of any instrument that aims to assess the complex range of NMS of PD in a unified and integrated manner. Recently, an international, multidisciplinary PD-NMS group has developed an integrated questionnaire and scale to assess NMS of PD in a comprehensive manner. This will help improve care and treatment of PD in the future.