Association between olfactory dysfunction and motor subtypes in Parkinson’s disease: are non‑tremor‑dominant subtypes really uncorrelated to olfactory impairment?

We read with great interest the two recent articles written by Nabizadeh and colleagues, and published in this journal, investigating respectively the association between olfactory impairment and three motor subtypes of Parkinson’s disease (PD) such as tremor-dominant (TD), postural instability with gait difculty (PIGD), and indeterminate subtypes, and possible diferent associations between olfactory dysfunction and striatal dopaminergic neuronal loss among the same motor PD subtypes.