阿尔茨海默病与轻度认知障碍患者初级嗅觉皮层的形态与功能改变

目的 确定阿尔茨海默病(AD)与轻度认知障碍(MCI)患者中初级嗅觉皮层的萎缩程度,并且探讨解剖学萎缩与嗅觉功能减低的内在联系.方法 选取12例AD、8例MCI患者和20名正常志愿者(NC),进行标准的嗅觉功能和神经学评分,而后进行高分辨率MRI和嗅觉fMRI.于T_1WI上确定初级嗅觉皮层的边界,并测量常规初级嗅觉皮层的容积,将此容积保存为ROI.然后采用事件相关的实验设计进行嗅觉fMRI,测量初级嗅觉皮层ROI内的激活体素.3组间的初级嗅觉皮层体积和激活范围比较采用Kruskal-Wallis秩和检验,如存在统计学差异则进行Bonferroni法两两比较.解剖学体积与激活范围情况的相关性在控制年龄因素下进行偏相关性分析.结果 NC、MCI和AD组初级嗅觉皮层的体积范围分别为3024～4734、1409～4553和1561～3759 mm~3,中位数分别为3749、2752和2156 mm~3;激活体素范围分别为0～2360、0～2160和0～100 mm~3,中位数分别为430、40和0 mm~3,NC、MCI和AD组初级嗅觉皮层体积和激活体素依次降低,差异有统计学意义(H值分别为14.942、16.587,P值均<0.05).初级嗅觉皮层内的激活与皮层体积的萎缩存在弱相关性(r=0.364,P=0.023).结论 AD初级嗅觉皮层存在明显萎缩与功能障碍,可以为AD的嗅觉功能障碍研究提供神经病理学和神经功能学依据.

The anatomical and functional changes in the primary olfactory cortex of Alzheimer disease and mild cognitive impairment patients

Objective To determine the volume reduction of the primary olfactory cortex (POC) in patients with Alzheimer disease (AD) and investigate the potential relationship of functional olfactory activation and anatomical atrophy changes. Methods Twelve patients with AD, eight patients with mild cognitive impairment (MCI) and twenty normal controls (NC) underwent standardized UPSIT (University of Pennsylvania smell identification test) behavior smell test and neuropsychological tests. Then all of the subjects underwent the high resolution MRI and an olfactory fMRI scan on a 3T system. Volumetric measurement of the POC was conducted and the areas were also saved as a ROI which would be used during the processing of fMRI data to get the activation voxels in local region. The Kruskal-Wallis rank test was used to examine the significance of POC volume and activation in three groups, If P-value was less than 0.05,Bonferroni method was used for multiple comparisons. The correlation between the anatomical volume and functional activation was analyzed with partial correlation adjusted for age. Results The POC volume of NC, MCI and AD groups were 3024--4734, 1409--4553 and 1561--3759 mm~3, and the medians were 3749, 2752 and 2156 mm~3. The activation voxels of each group were 0--2360, 0--2160 and 0--100 mm~3, while the medians were 430, 40 and 0 mm~3. There were significant differences of both POC volume atrophy and activation between the three groups, with a trend of reduction from NC to MCI to AD group (H is 14.942 and 16.587, both P<0.05). The volume of olfactory activation at POC was highly correlated with the volume of POC (r=0.364, P=0.023). Conclusions In this study, we explored the morphological and functional changes in the POC. It is revealed that POC suffers prominent local atrophy and dysfunction as well as hippocampus in AD. These results can provide neuropathological and neurofunctional bases for olfactory deficit in Alzheimer Disease.