Serra Laura, Bruschini Michela, Di Domenico Carlotta, Gabrielli Giulia Bechi, Marra Camillo, Caltagirone Carlo, Cercignani Mara, Bozzali Marco
Neuroimaging Laboratory, Santa Lucia Foundation, IRCCS, Rome, Italy.
Institute of Neurology, Catholic University, Rome, Italy.
J Alzheimers Dis. 2017;58(1):171-184. doi: 10.3233/JAD-170086.
Changes in the residual memory variance are considered as a dynamic aspect of cognitive reserve (d-CR). We aimed to investigate for the first time the neural substrate associated with changes in the residual memory variance overtime in patients with amnestic mild cognitive impairment (aMCI). Thirty-four aMCI patients followed-up for 36 months and 48 healthy elderly individuals (HE) were recruited. All participants underwent 3T MRI, collecting T1-weighted images for voxel-based morphometry (VBM). They underwent an extensive neuropsychological battery, including six episodic memory tests. In patients and controls, factor analyses were used on the episodic memory scores to obtain a composite memory score (C-MS). Partial Least Square analyses were used to decompose the variance of C-MS in latent variables (LT scores), accounting for demographic variables and for the general cognitive efficiency level; linear regressions were applied on LT scores, striping off any contribution of general cognitive abilities, to obtain the residual value of memory variance, considered as an index of d-CR. LT scores and d-CR were used in discriminant analysis, in patients only. Finally, LT scores and d-CR were used as variable of interest in VBM analysis. The d-CR score was not able to correctly classify patients. In both aMCI patients and HE, LT1st and d-CR scores showed correlations with grey matter volumes in common and in specific brain areas. Using CR measures limited to assess memory function is likely less sensitive to detect the cognitive decline and predict the evolution of Alzheimer's disease. In conclusion, d-CR needs a measure of general cognition to identify conversion to Alzheimer's disease efficiently.
残余记忆方差的变化被视为认知储备的动态方面（d-CR）。我们旨在首次研究遗忘型轻度认知障碍（aMCI）患者残余记忆方差随时间变化相关的神经基质。招募了34名随访36个月的aMCI患者和48名健康老年人（HE）。所有参与者均接受3T磁共振成像（MRI），采集T1加权图像用于基于体素的形态学测量（VBM）。他们接受了广泛的神经心理学测试，包括六项情景记忆测试。在患者和对照组中，对情景记忆分数进行因子分析以获得综合记忆分数（C-MS）。使用偏最小二乘分析将C-MS的方差分解为潜在变量（LT分数），同时考虑人口统计学变量和一般认知效率水平；对LT分数进行线性回归，去除一般认知能力的任何贡献，以获得记忆方差的残差值，将其视为d-CR的指标。仅在患者中使用LT分数和d-CR进行判别分析。最后，将LT分数和d-CR用作VBM分析中的感兴趣变量。d-CR分数无法正确对患者进行分类。在aMCI患者和HE中，LT1st和d-CR分数均与共同和特定脑区的灰质体积相关。仅使用限于评估记忆功能的CR测量可能对检测认知衰退和预测阿尔茨海默病的进展不太敏感。总之，d-CR需要一种一般认知测量方法来有效地识别向阿尔茨海默病的转化。
