Nicolas Renaud, Hiba Bassem, Dilharreguy Bixente, Barse Elodie, Baillet Marion, Edde Manon, Pelletier Amandine, Periot Olivier, Helmer Catherine, Allard Michele, Dartigues Jean-François, Amieva Hélène, Pérès Karine, Fernandez Philippe, Catheline Gwénaëlle
Université de Bordeaux, INCIA, UMR 5287-équipe NeuroImagerie et Cognition Humaine, Bordeaux, France.
CNRS, INCIA, UMR 5287-équipe NeuroImagerie et Cognition Humaine, Bordeaux, France.
Front Aging Neurosci. 2020 Aug 14;12:218. doi: 10.3389/fnagi.2020.00218. eCollection 2020.
: Extensive research using water-diffusion MRI reported age-related modifications of cerebral White Matter (WM). Moreover, water-diffusion parameter modifications have been frequently associated with cognitive performances in the elderly sample, reinforcing the idea of aging inducing microstructural disconnection of the brain which in turn impacts cognition. However, only few studies really assessed over-time modifications of these parameters and their relationship with episodic memory outcome of elderly. : One-hundred and thirty elderly subjects without dementia (74.1 ± 4.1 years; 47% female) were included in this study. Diffusion tensor imaging (DTI) was performed at two-time points (3.49 ± 0.68 years apart), allowing the assessment of changes in water-diffusion parameters over time using a specific longitudinal pipeline. White matter hyperintensity (WMH) burden and gray matter (GM) atrophy were also measured on FLAIR and T1-weighted sequences collected during these two MRI sessions. Free and cued verbal recall scores assessed at the last follow-up of the cohort were used as episodic memory outcome. Changes in water-diffusion parameters over time were included in serial linear regression models to predict retrieval or storage ability of elderly. : GM atrophy and an increase in mean diffusivity (MD) and WMH load between the two-time points were observed. The increase in MD was significantly correlated with WMH load and the different memory scores. In models accounting for the baseline cognitive score, GM atrophy, or WMH load, MD changes still significantly predict free verbal recall, and not total verbal recall, suggesting the specific association with the retrieval deficit in healthy aging. : In elderly, microstructural WM changes are good predictors of lower free verbal recall performances. Moreover, this contribution is not only driven by WMH load increase. This last observation is in line with studies reporting early water-diffusion modification in WM tissue during aging, resulting lately in the appearance of WMH on conventional MRI.
: 使用水扩散磁共振成像的大量研究报告了脑白质（WM）与年龄相关的变化。此外，水扩散参数的变化在老年样本中经常与认知表现相关，强化了衰老导致大脑微观结构断开连接进而影响认知的观点。然而，只有少数研究真正评估了这些参数随时间的变化及其与老年人情景记忆结果的关系。: 本研究纳入了130名无痴呆的老年人（74.1±4.1岁；47%为女性）。在两个时间点（相隔3.49±0.68年）进行扩散张量成像（DTI），使用特定的纵向流程评估水扩散参数随时间的变化。在这两次MRI检查期间采集的FLAIR和T1加权序列上还测量了白质高信号（WMH）负荷和灰质（GM）萎缩。在队列的最后一次随访时评估的自由和线索性言语回忆分数用作情景记忆结果。水扩散参数随时间的变化纳入系列线性回归模型，以预测老年人的检索或存储能力。: 观察到两个时间点之间GM萎缩以及平均扩散率（MD）和WMH负荷增加。MD的增加与WMH负荷和不同的记忆分数显著相关。在考虑基线认知分数、GM萎缩或WMH负荷的模型中，MD变化仍然显著预测自由言语回忆，而不是总言语回忆，表明与健康衰老中的检索缺陷存在特定关联。: 在老年人中，微观结构的WM变化是较低自由言语回忆表现的良好预测指标。此外，这种影响不仅由WMH负荷增加驱动。最后这一观察结果与报告衰老期间WM组织早期水扩散改变、随后在传统MRI上出现WMH的研究一致。
