阿尔茨海默氏症患者大脑的结构偏侧性研究

Structural Lateralization in Brains of Patients with Alzheimer's Disease

偏侧性是大脑实现高效、多任务功能活动的特性之一,阿尔茨海默氏症(AD)的病理改变会导致大脑结构和功能偏侧性出现异常。文章分别选取了39例AD病人与正常老年人的大脑结构磁共振和弥散张量磁共振图像,将其大脑分成34个感兴趣区域并计算了左右半球各区域的大脑皮层表面积、沟回指数、皮层厚度、皮层下白质体积、白质纤维束部分各向异性共5个参数。经检验统计分析后发现,大脑皮层左右半球的形态结构差异主要位于前额叶、颞叶、边缘系统等最易受衰老和AD病变影响的区域,AD患者的大脑偏侧性较正常老年人减弱,尤其在内嗅皮层上,灰质、白质偏侧性同时消失。大脑偏侧性研究对加深AD发病机理的认识及提高该疾病的临床诊疗有重要意义。

Hemispheric asymmetry is believed to increase the efficiency of information processing, especially for the multitask performance. Regional variation of cerebral lateralization was observed in healthy elderly as well as in patients with Alzheimer's disease(AD). However, the extent and degree of the alterations in the cerebral lateralization in AD patients remained controversial. In the current study, high-resolution T1-weighted magnetic resonance images(T1WI) and diffusion tensor images(DTI) were retrieved consecutively for a total of 78 AD patients and healthy elderly from the open database of ADNI(http://adni.loni.ucla.edu/). The entire brain of each subject was parcellated into 34 regions of interest(ROIs) for each hemisphere. Five variables including cortical surface area, curvature index, cortical thickness, subjacent white matter volume,and fractional anisotropy(FA) of white matter fiber tracts were calculated for each ROI. Inter-hemisphere difference of the aforementioned parameters was analyzed using univariate and multivariate models for each ROI. The statistics parametric images were mapped on the anatomy template to facilitate visual inspection. Significant morphological variation between hemispheres was identified mainly in the lateral prefrontal cortex and temporal lobe, medial parietal lobe and limbic system which were vulnerable in both healthy aging and AD. Cerebral lateralization reduced significantly in AD patient in comparison with healthy elderly, especially in the entorhinal cortex, the gray matter lateralization and white matter lateralization both vanished. Univariate and multivariate analyses of the alterations in the cerebral lateralization might add extra values of the morphological information in evaluating the disease dynamic of AD and other dementia disorders.