The importance of non-motor disturbances to quality of life in Parkinson's disease

The term health-related quality of life (HRQoL) refers to the consequences of the disease and treatment on the patients' life, as perceived and evaluated by patients themselves. Parkinson's disease is a complex disorder characterized by motor manifestations and an impressive diversity of non-motor symptoms (NMS) that may be simultaneously present in the same patient. Some of these non-motor symptoms (for example, depression, fatigue, or pain) have got evidence enough to be considered determinant factors of HRQoL. For others, evidence is incomplete or results of the studies are inconsistent. The availability of instruments for assessment of a wide set of NMS allows to evaluate the impact of NMS, as a whole and compared to the motor disorder, on the HRQoL. In that scenario, the whole NMS showed a close association with the quality of life deterioration, exceeding even the effects of the motor disorder.