Non-motor Symptoms in Parkinson’s Disease

Abstract

In addition to typical motor dysfunction (parkinsonism), diverse non-motor symptoms (NMS) are frequently observed in patients with Parkinson’s disease (PD). Some NMS may antedate the diagnosis of PD. Examples of NMS include cognitive impairment, autonomic dysfunction, visual dysfunction, sleep abnormalities, and psychiatric disorders. NMS are associated with wide-ranging abnormalities in extranigral dopaminergic systems and non-dopaminergic (e.g. cholinergic, noradrenergic, serotoninergic) systems. The type and severity of NMS vary based on age, disease severity, and predominant motor symptoms. NMS can be disabling and reduce quality of life. Treatment of NMS can be challenging. Some NMS are helped by dopaminergic treatment, whereas others can be induced or exacerbated by treatments that help the motor dysfunction. Physicians should probe their PD patients about their NMS and address them for better care. Clinical trials should incorporate NMS as outcomes for more meaningful conclusions on the effect of treatments under investigation.