Olfactory Impairment in Parkinson's Disease Patients with Tremor Dominant Subtype Compared to Those with Akinetic Rigid Dominant Subtype: A Pilot Study.

Paolo Solla,Tommaso Ercoli,Laura Fadda,Francesco Loy,Ilenia Pinna,Carla Masala,Gianni Orofino,Giovanni Defazio

doi:10.3390/brainsci12020196

Paolo Solla, Tommaso Ercoli + Show 6 more

Open Access

https://doi.org/10.3390/brainsci12020196

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Journal: Brain sciences	Publication Date: Jan 31, 2022
Citations: 6	License type: CC BY 4.0

Affiliation: University of Cagliari, University of Sassari

Abstract

Background: Parkinson’s disease (PD) may present different motor subtypes depending on the predominant symptoms (tremor or rigidity/bradykinesia). Slower disease progression and cognitive decline were observed in tremor-dominant (TD) patients compared to those with the akinetic-rigid dominant (ARD) subtype. Although olfactory dysfunctions are well-known disturbances in PD patients, correlations among PD different subtypes and olfactory impairment were not clearly studied. Thus, we investigated the possible olfactory impairment in PD patients with TD and ARD subtypes as compared to healthy controls. Methods: A sample of 132 participants were enrolled: 62 PD patients divided into ARD (n = 42) and TD (n = 20) subgroups using tremor/rigidity ratio, and 70 healthy controls. Olfactory function was assessed with the Sniffin’ Sticks Test. Results: Odor threshold was significantly lower in the ARD than in the TD subtype, while odor identification, discrimination scores, and their sum (TDI score) were not significantly different. On multivariate linear regression analysis, the tremor/rigidity ratio was a significant predictor of odor threshold. Conclusions: Our pilot study showed a significant olfactory dysfunction in PD patients with the ARD subtype. This evidence confirms the biological relevance of clinical subgroups in PD patients, suggesting the existence of a different pathophysiological mechanism between the ARD and TD clinical subtypes.

Highlights

Parkinson’s disease (PD) is a chronic neurodegenerative disorder characterized by motor symptoms (MSs) and non-motor symptoms (NMSs) [1]
In order to advance the comprehension of the neural mechanism involved in the clinical manifestation of these subtypes, our aim was to investigate odor threshold, odor discrimination, and odor identification in PD patients with the TD and akinetic-rigid dominant (ARD) subtypes compared to healthy controls
Our findings suggested a significant difference in olfactory impairment between PD patients with the TD subtype in comparison to those with the ARD subtype

Summary

Introduction

Parkinson’s disease (PD) is a chronic neurodegenerative disorder characterized by motor symptoms (MSs) and non-motor symptoms (NMSs) [1]. Bradykinesia, along with tremors, rigidity, and postural instability, are the main common MSs, while among the NMSs are cardiovascular disorders, sleep, cognitive impairment, and visual, taste, and olfactory dysfunctions [2]. Parkinson’s disease (PD) may present different motor subtypes depending on the predominant symptoms (tremor or rigidity/bradykinesia). Slower disease progression and cognitive decline were observed in tremor-dominant (TD) patients compared to those with the akinetic-rigid dominant (ARD) subtype. Conclusions: Our pilot study showed a significant olfactory dysfunction in PD patients with the ARD subtype. This evidence confirms the biological relevance of clinical subgroups in PD patients, suggesting the existence of a different pathophysiological mechanism between the ARD and TD clinical subtypes

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