“Patients with idiopathic smell loss constitute an at-risk population for the development of Parkinson’s disease (PD). The study aimed to follow up a large number of patients with idiopathic smell and/or taste loss to define the incidence of PD in this population and, further, to assess characteristics of both olfactory and gustatory function and their possible association with PD development….”

Haehner A, Masala C, Walter S, Reichmann H and Hummel T: Incidence of Parkinson’s disease in a large patient cohort with idiopathic smell and taste loss. J. Neurology 266: 339-345 (2019).