Lancet neurology
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Non-motor symptoms (NMS) of Parkinson's disease can be predominant as the disease advances, thereby constituting a major source of disease burden for patients and caregivers. However, current understanding of NMS is incomplete, particularly as a result of the absence of standardisation of outcome definitions and the heterogeneity of the risk factors that are assessed. ⋯ Disease severity, sex, age, and antiparkinsonian medication might have roles in the development of different NMS, although only antiparkinsonian medication is potentially modifiable. Until disease-modifying therapies are developed, increased knowledge of risk factors could ameliorate early identification of patients who are at an increased risk of developing specific NMS and potentially allow improvement of symptom management or prevention of specific NMS.