Masala C, et al. - Researchers examined olfactory function, cognitive impairment, apathy, and fatigue in patients with Parkinson’s disease (PD) vs healthy controls, and subsequently investigated the relationships between these non-motor symptoms (NMS) and motor symptoms severity in subjects with PD. This study was conducted on 147 participants, and used the Sniffin’ Sticks test to evaluate olfactory function. Changes in apathy and motor disability were significant predictors for altered of odor identification, discrimination, and Threshold–Discrimination–Identification (TDI) score. Results of this study suggested that olfactory dysfunction could progress in close relation with both motor impairment Unified PD Rating Scale (UPDRS, and non-motor symptoms, such as apathy.