Non-Motor Symptoms: The Hidden Face of Parkinson’s Disease

Non-motor symptoms (NMS) of Parkinson's disease (PD) were recognized by James Parkinson himself about 200 years ago and are now considered to be an integral part of PD, significantly contributing to the worse of patients’ quality of life. Although awareness of NMS is growing, and several scientific societies have now dedicated non-motor study groups, the NMS burden is still the hidden face of PD and in most cases the clinicians’ views are focused on the motor symptoms alone. Literature research has been performed using several databases and scientific journals; this review provides a comprehensive description of the most common NMS in PD, their clinical phenotype, social impact, diagnosis, and therapeutic management. Early recognition of these features may lead to more prompt and effective treatment and may help to better understand patients’ needs.