目的 采用功能磁共振(fMRI)技术,观察轻度阿尔茨海默病(AD)、遗忘型轻度认知功能障碍(aMCI)患者静息态脑自发活动变化,探讨fMRI成像标志物对诊断AD及aMCI的临床价值.方法 以临床诊断aMCI、诊断很可能AD患者和正常认知对照组各12例为研究对象,对其进行简易精神状态检查(MMSE)评分和静息态fMRI扫描,利用分数低频振幅(fA LFF)方法对静息态大脑自发活动进行对比分析,观察AD患者、aMCI患者相对于对照组在fALFF指标有显著差异的区域.结果 静息态fMRI结果显示,在楔前叶,AD组fALFF值(1.11±0.07)与对照组(1.24 ±0.11,t=2.89,P=0.012)和aMCI组(1.34±0.17,t=3.49,P=0.004)相比均显著下降,aMCI组fALFF值最高,但与对照组相比差异无统计学意义;在顶下小叶,AD组fALFF值(0.96±0.07)和对照组(1.11±0.07,t4.31,P =0.001)、aMCI组(1.09±0.08,t=3.44,P=0.004)相比均显著下降.结论 AD患者较aMCI患者及正常认知老年人脑内特定区域自发活动受损明显;aMCI患者脑内特定区域自发活动与对照组相比无显著改变,但在某些和高级神经功能密切相关的区域如楔前叶有代偿增强的倾向.%Objective To investigate the functional changes of brain spontaneous activity in patients with Alzheimer' s disease (AD) and amnestic mild cognitive impairment (aMCI) using resting-state functional magnetic resonance imaging (fMR1), and evaluate the potential value of fMRI marker in clinical diagnosis of AD and aMCI.Methods Twelve AD patients, 12 aMCI patients and 12 normal controls (NC) were assessed by the Minimum Mental State Examination (MMSE) and scanned using the resting-state fMRI.The fractional amplitude of low-frequency fluctuations (fALFF) method was employed to examine the changes of the brain spontaneous activity among the three groups.Results Significant between-group differences were found in the precuneus and the inferior parietal lobe.In the precuneus, the fALFF value in AD patients (mean ± SD : 1.11 ± 0.07) was significantly decreased as compared to NC (1.24 ± 0.11, t =2.89,P =0.012) and aMCI patients (1.34 ±0.17,t =3.49,P =0.004).The aMCI patients demonstrated numerically largest fALFF in the precuneus.In the inferior parietal lobe, the fALFF values in AD patients (0.96 ±0.07) were also significantly decreased as compared to NC (1.11 ±0.07 ,t =4.31 ,P =0.001) and aMCI patients (1.09 ± 0.08, t =3.44, P =0.004).Conclusions AD patients were mostly influenced in the specific regions in terms of brain spontaneous activity, while the aMCI patients showed a compensatory tendency in the precuneus.
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