Olfactory function in patients with mild cognitive impairment

Abstract

To analyze the correlation between olfactory bulb (OB) volume, depth of olfactory sulcus (OS) and olfactory function in patients with mild cognitive impairment (MCI). Fifty patients with MCI were compared with fifty controls in terms of olfactory function T&T testing, OB volume and depth of OS assessed with magnetic resonance imaging (MRI). SPSS 13.0 software was used to analyze the data. T&T olfactory testing revealed that MCI patients had higher scores than controls (t = 3.142, P < 0.05). Both men and women with MCI were affected by the same extent of olfactory loss(t = 0.973, P > 0.05). Both men and women as controls were affected by the same extent of olfactory loss (t = 1.092, P > 0.05).OB volume of left side in MCI patients was (36.35 ± 4.09) mm(3), right side was (36.57 ± 4.13) mm(3), average OB volume was (36.47 ± 4.12) mm3; OB volume of left side in controls was (46.65 ± 6.23) mm(3), right side was (46.83 ± 6.27) mm(3), average OB volume was (46.71 ± 6.25)mm(3); OB volumes were lower in MCI patients as compared with controls (t value was 3.113, 3.145 and 3.132, all P < 0.01).OS depth study revealed no statistical different between MCI patients and controls (t value was 0.876,0.952 and 0.904, all P > 0.05). Olfactory discriminate threshold was negatively correlated with OB volume in MCI patients and controls (r value was -0.643, -0.541, both P < 0.05); was no correlated with depth of OS (r value was -0.167 and -0.183, both P > 0.05). Olfactory discriminate threshold was negatively correlated with cognitive impairment degree in MCI patients (r value was -0.427, -0.418 and -0.399, all P < 0.05), average OB volume was positively correlated with cognitive impairment degree in MCI patients (r value was 0.364, 0.383 and 0.379, all P < 0.05). The OB volumes are lower in MCI patients as compared with controls, the depth of OS show no significant changes in MCI patients. The OB volume is correlated with olfactory function, the depth of OS is not correlated with olfactory function. Cognitive impairment degree in MCI patients is accordance with olfactory function lower degree. The olfactory loss may be a earlier period and objective diagnosis indicator for MCI patients.