Olfactory Dysfunction Predicts Disease Progression in Parkinson's Disease: A Longitudinal Study.

Runcheng He,Qian Xu,Yangjie Zhou,Liping Zhu,Yan He,Jinxia Yang,Beisha Tang,Xiaoting Zhou,Xun Zhou,Zhenhua Liu,Qiying Sun,Jieqiong Tan,Yuwen Zhao,Xinxiang Yan,Jifeng Guo

doi:10.3389/fnins.2020.569777

Runcheng He, Qian Xu + Show 13 more

Open Access

https://doi.org/10.3389/fnins.2020.569777

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Abstract

Background and Objective:Olfactory dysfunction (hyposmia) is an important non-motor symptom of Parkinson’s disease (PD). To investigate the potential prognostic value of hyposmia as a marker for disease progression, we prospectively assessed clinical manifestations and longitudinal changes of hyposmic PD patients and normosmic ones.MethodsOlfactory function was evaluated with the Sniffin’ Sticks in PD patients at baseline. One hundred five hyposmic PD patients and 59 normosmic PD patients were enrolled and followed up for 2 years. They were subsequently evaluated at baseline and during follow-up periods with neurological and neuropsychological assessments. Clinical manifestations and disease progressions were compared between hyposmic and normosmic patients. In addition, the relationship between disease progressions and olfactory function was analyzed.ResultsOur study suggested that hyposmic PD patients and normosmic ones were similar in gender, age, education levels, age of onset, disease duration, and clinical features at baseline. Hyposmic PD patients exhibited more severe Unified Parkinson’s Disease Rating Scale Part II–III (UPDRS II-III) scores, higher levodopa equivalent dose (LED) needs, and poorer Mini-Mental State Examination (MMSE) score at follow-up visits compared to those in normosmic PD patients. Hyposmia also showed greater rates in the increase of LED needs, improvement of UPDRS III score, and deterioration of MMSE score. Both improvement of UPDRS III score and decline of MMSE score were associated with poorer odor identification.ConclusionOur prospective study demonstrated that hyposmic PD patients showed a relatively worse clinical course compared with normosmic patients. Olfactory dysfunction is a useful predictor of disease progression.

Highlights

Parkinson’s disease (PD) is one of the common progressive neurodegenerative disorders characterized by several motor and non-motor symptoms (NMSs)
There were no significant differences between two groups in UPDRS I– III subscale scores, proportion of motor subtypes, H-Y scale, levodopa equivalent dose (LED) needs, Non-motor symptoms scale (NMSS) total scores, NMSS subscores, proportion of dyskinesia, or freezing
Our study demonstrated that both normosmic and hyposmic PD patients had significantly reduced the NMSS scores at the follow-up period, and we suspect a dominant role of levodopa medications here

Summary

Introduction

Parkinson’s disease (PD) is one of the common progressive neurodegenerative disorders characterized by several motor and non-motor symptoms (NMSs). Rey et al (2016) triggered α-synuclein pathology in the olfactory bulb of mice by local injections of fibrillar α-synuclein, and they found that it can gradually spread to a total of over 40 different brain regions or subregions that are affected in PD over the course of 12 months. They detected α-synuclein inclusions in neocortical brain regions (Rey et al, 2016). To investigate the potential prognostic value of hyposmia as a marker for disease progression, we prospectively assessed clinical manifestations and longitudinal changes of hyposmic PD patients and normosmic ones

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