Non-motor signs in Parkinson's disease: a review

During the past decade the view of Parkinson's disease (PD) as a motor disorder has changed significantly and currently it is recognized as a multisystem process with diverse non-motor signs (NMS). In addition to been extremely common, these NMS play a major role in undermining functionality and quality of life. On the other hand, NMS are under recognized by physicians and neglected by patients. Here, we review the most common NMS in PD, including cognitive, psychiatric, sleep, metabolic, and sensory disturbances, discuss the current knowledge from biological, epidemiological, clinical, and prognostic standpoints, highlighting the need for early recognition and management.