MR Volumetric Analysis Of Piriform-Cortical Amygdala And Orbitofrontal Cortices Of Healthy Chinese Adults Combined With Sniffin' Sticks: The Aging Effect

Objective: The aim of this study was to depict the changing rules of MRI volumes of Piriform-Cortical Amygdala (PCA), Orbitofrontal Cortices (OFC) and olfactory function, and the relationships between volumes of PCA, OFC and age in Chinese healthy adults, also the normal volumes of each age group.Methods: One hundred and eleven healthy right-handed participants (54 males, 57 females) excluding all the possible causes of olfactory dysfunction, from age 20 to 70 years were recruited to join this study, average age 44.2±14.0 years old . Subjects were divided by every ten years into five age groups. All the subjects accept MRI scan, and volumetric measurements of the PCA and OFC were performed using consecutive 1-mm thick coronal slices of high-resolution 3-D MRIs with Dr. view software. Olfactory function was assessed using a validated olfactory function test (Sniffin'Sticks), including odor threshold (THR), odor discrimination (DIS), and odor identification (ID). SPSS16.0 was used to analysis the change rules of volumes in Piriform-Cortical Amygdala (PCA), Orbitofrontal Cortices (OFC) and olfactory function, and the relationships between volumes of PCA, OFC and age in Chinese healthy adults.Results: The PCA volume of men was (0.502±0.048) cm³ on the left and (0.518±0.049) cm³ on the right side. The PCA volume of women was (0.490±0.057) cm³ on the left and (0.502±0.042) cm³ on the right side. And for the volume of OFC, The volume of men was (13.966±2.456) cm³ on the left and (13.581±2.359) cm³ on the right side. The volume of women was (12.466±2.123) cm³ on the left and (12.299±1.943) cm³ on the right side. Significant age differences were observed in the volume of OFC, shown as becoming significantly reduced after 40 years old; and for olfactory function, shown as being significantly decreased after 60 years old compared with those of the younger. Similar age-related volumetric changes were not found in the PCA. Additionally, Pearson partial correlation analyses controlling for ICV revealed significant correlations between age and the volume of OFC, and between olfactory functions and the volume of OFC, shown as a significant correlation between age and volume of OFC(left: _r108 = -0.387, p < 0.001; right: _r108 = -0.364, p < 0.001), and a significant correlation between OFC and DIS on the right side (_r108 = 0.209, p = 0.028), and a trend-level significant correlation on the left side (_r108 = 0.165, p = 0.085). The correlations between OFC and TDI were significant on both sides (left: _r108 = 0.229, p = 0.016; right: _r108 = 0.238, p = 0.012). The correlation between the OFC and ID was also trend-level significant bilaterally (left: _r108 = 0.171, p = 0.075; right: _r108 = 0.169, p = 0.077). Such kinds of correlations were not detected in the PCA (p > 0.05).Conclusion: Taking together, the present data might be expected to contribute to establishing normative database for olfactory function and volumes of PCA and OFC. The volumes of bilateral OFC but not of the PCA and the olfactory function were significantly declined with age. Shown as the volume of OFC become significantly reduced after 40 years old; and for olfactory function, shown as being significantly decreased after 60 years old compared with those of the younger. In additionally, the volume of OFC but not the PCA was significantly correlated with olfactory functions, especially the odor discrimination. The present data might be useful in assessing the diseases which affect olfaction.