A Preliminary DTI Study On Olfactory Disorder In Newly Diagnosed Drug-naive Patients With Parkinson's Disease

Objectives:We analyzed the diffuse tensor imaging(DTI)data of newly diagnosed drug-naive Parkinson's disease(PD)patients with/without hyposmia and normal controls to provide insight into the pathological mechanism of olfactory dysfunction.Methods: A total of 15 newly diagnosed drug-naive PD patients from the Department of Neurology,Affiliated Hospital of North Sichuan Medical College were consecutively recruited in this cross-sectional study between July 2017 and December 2017.The Non-Motor Symptom Scale(NMSS),Unified PD Rating Scale part ?(UPDRS ?),and Hoehn and Yahr(H&Y)stage were used to access the motor symptoms and NMS.The global cognitive function was evaluated using the Montreal Cognitive Assessment(MoCA).Depression and anxiety were assessed using the Hamilton Depression Rating Scale(HAMD)and the Hamilton Anxiety Rating Scale(HAMD),respectively.The olfactory function was evaluated using Argentina Hyposmia Rating Scale(AHRS).The fatigue and sleep condition were evaluated using the Fatigue Severity Scale(FSS)and the Parkinson Disease Sleep Scale(PDSS),respectively.The health-related quality of life was assessed using the 39-item Parkinson's Disease Questionnaire(PDQ-39).Magnetic resonance imaging(MRI)examination was performed on GE Discovery MR750 3.0T superconducting magnetic resonance scanner.Results: Olfactory dysfunction was observed in 58.1% of newly diagnosed drug-naive PD patients.Compared with normal controls,fractionaanisotropy(FA)of PD patients in Caudate_L and anterior limb of internal capsule decreased significantly.Compared with PD patients without hypomia,PD patients with hyposmia showed FA significant reduction in right putamen and right corticospinal tract.Compared with normal controls,mean diffusivity(MD)in right precentral gyrus and left superior temporal decreased significantly but MD in left caudate and superior longitudinal fasciculus increased significantly in PD patients with hyposmia.Compared with PD patients without hypomia,PD patients with hyposmia MD in left middle frontal gyrus,left superior frontal gyrus and left orbital superior frontal gyrus significantly increased.All the results were corrected by AlphaSim.FA in right putamen was associated with AHRS scores(r=-0.597 p=0.019)and UPDRS II scores(r=0.737 p=0.023),MD in left superior frontal gyrus was positively correlated with HAMA scores(r=0.595 p=0.025).Conclusions: Olfactory dysfunction was common in PD and related to subtle structural changes in right Putamen,left middle frontal gyrus,left superior frontal gyrus and left orbital superior frontal gyrus.