ABSTRACT
Objective To investigate the subtle changes of the brain function at olfactory region of MD patients with olfactory dysfunction at resting state, through the application of fMRI-BOLD. Methods This study enrolled 28 MD patients with olfactory dysfunction(Case group) who had been treated from February 2016 to March 2017, and 23 healthy volunteers (Control group) with matching gender, age and education background to the Case group.All subjects were examined by Symptoms Checklists-90(SCL-90), Hamilton Depression Rating Scale-24 (HAMD-24), 70% isopropyl alcohol inhalation test, and fMRI at resting state. The two independent samples t test was used to compare the two groups' educational years, psychological scales and olfactory test scores.Regional homogeneity(ReHo)analysis was conducted for the whole brain of subjects.The ReHo values at some brain regions of both groups were compared through two independent sample t-test.The ReHo values,extracted from the case group's brain regions with differences, were run through by Pearson correlation analysis.Results There was a negative correlation between the HAMD-24 score(r=-0.413,P=0.029)and the severity of olfactory decline in the MD patients with olfactory dysfunction.In addition,it was found by fMRI that Case group,as compared to Control group,demonstrate declined ReHo values at left orbital frontal gyrus(cluster=80,t=3.27),bilateral cingulate gyrus(right cluster=204,t=4.34,left cluster=204,t=3.63),bilateral middle frontal gyrus(right cluster=56,t=3.67,left cluster=28, t=3.50),rightinsular(cluster=40,t=3.53),bilateral amygdala(right cluster=76,t=3.66,left cluster=86,t=2.93),but increased ReHo values at bilateral inferior frontal gyrus(right cluster=44,t=3.62,left cluster=33,t=3.25), right thalamus(cluster=34, t=3.21)and bilateral gyri rectus(right cluster=45,t=3.78,left cluster=24,t=3.01)(AlphaSim correction,P<0.001).Moreover,there was a positive correlation between the ReHo value at left orbital frontal gyrus and the olfactory test distance(r=0.628,P<0.05).But the ReHo value at left orbital frontal gyruswas negatively correlated with HAMD-24 (r=-0.414,P=0.029). There was no correlation with other clinical data.Conclusion The abnormal brain functional activities of left orbital frontal gyrus at resting state might be related to the olfactory dysfunction of patients with depression.