The use of olfactory testing when diagnosing Parkinson's disease - a systematic review.

The diagnosis of Parkinson's disease (PD) is typically based on the presence of motor symptoms, but in the early phase of the disease, the diagnostic process can be challenging. Examination of non-motor symptoms in patients suspected of PD has gained growing attention. Olfactory tests have shown promising results as ancillary diagnostic tests. The aim of this study was to investigate how olfactory tests may be used clinically in diagnostic process in PD.