Olfactory Impairment and Hippocampal Volume in a Chinese MCI Clinical Sample.

Purpose: The aim of this study was to evaluate the relationship between olfactory function and hippocampal volume in patients with mild cognitive impairment (MCI). Methods: We enrolled a total of 31 MCI patients and 9 normal control subjects. All participants underwent 3.0 T-magnetic resonance imaging scanning. The scan results were processed using GE ADW4.6 processing software and V0xar 3D workstation to acquire the hippocampal volume. The University of Pennsylvania Smell Identification Test (UPSIT) was used to evaluate the olfactory function of MCI patients. The correlations of UPSIT score with hippocampal volume and hippocampal head volume were evaluated by Pearson correlation coefficient analysis. Results: MCI patients had significantly smaller left (2.78 +/- 0.50 vs. 3.19 +/- 0.31 cm(3)) and right (2.97 +/- 0.42 vs. 3.31 +/- 0.25 cm(3)) hippocampal volumes compared with normal controls (P<0.05). In addition, patients with olfactory dysfunction had smaller volumes of the hippocampus (left hippocampal volume, 2.57 +/- 0.39 vs. 3.23 +/- 0.40 cm(3); right hippocampal volume, 2.86 +/- 0.43 vs. 3.22 +/- 0.30 cm(3)) and hippocampal head (left hippocampal head volume, 1.18 +/- 0.16 vs. 1.53 +/- 0.25 cm(3); right hippocampal head volume, 1.25 +/- 0.22 vs. 1.54 +/- 0.22 cm(3)) compared with those with normal olfactory function (P<0.05). No significant difference in the hippocampal body volume and hippocampal tail volume was found between MCI patients with olfactory loss and those with normal olfactory function. The UPSIT score was significantly positively correlated with left hippocampal volume (r=0.55, P<0.05), right hippocampal volume (r=0.42, P<0.05), left hippocampal head volume (r=0.53, P<0.05), and right hippocampal head volume (r=0.45, P<0.05). Conclusions: Olfactory function correlates well with hippocampal volume among patients with MCI.