Beaudet Grégory, Tsuchida Ami, Petit Laurent, Tzourio Christophe, Caspers Svenja, Schreiber Jan, Pausova Zdenka, Patel Yash, Paus Tomas, Schmidt Reinhold, Pirpamer Lukas, Sachdev Perminder S, Brodaty Henry, Kochan Nicole, Trollor Julian, Wen Wei, Armstrong Nicola J, Deary Ian J, Bastin Mark E, Wardlaw Joanna M, Munõz Maniega Susana, Witte A Veronica, Villringer Arno, Duering Marco, Debette Stéphanie, Mazoyer Bernard
Institute of Neurodegenerative Diseases (IMN), CNRS, CEA, Bordeaux, France.
Institute of Neurodegenerative Diseases (IMN), University of Bordeaux, Bordeaux, France.
Front Psychiatry. 2020 May 4;11:342. doi: 10.3389/fpsyt.2020.00342. eCollection 2020.
Parameters of water diffusion in white matter derived from diffusion-weighted imaging (DWI), such as fractional anisotropy (FA), mean, axial, and radial diffusivity (MD, AD, and RD), and more recently, peak width of skeletonized mean diffusivity (PSMD), have been proposed as potential markers of normal and pathological brain ageing. However, their relative evolution over the entire adult lifespan in healthy individuals remains partly unknown during early and late adulthood, and particularly for the PSMD index. Here, we gathered and analyzed cross-sectional diffusion tensor imaging (DTI) data from 10 population-based cohort studies in order to establish the time course of white matter water diffusion phenotypes from post-adolescence to late adulthood. DTI data were obtained from a total of 20,005 individuals aged 18.1 to 92.6 years and analyzed with the same pipeline for computing skeletonized DTI metrics from DTI maps. For each individual, MD, AD, RD, and FA mean values were computed over their FA volume skeleton, PSMD being calculated as the 90% peak width of the MD values distribution across the FA skeleton. Mean values of each DTI metric were found to strongly vary across cohorts, most likely due to major differences in DWI acquisition protocols as well as pre-processing and DTI model fitting. However, age effects on each DTI metric were found to be highly consistent across cohorts. RD, MD, and AD variations with age exhibited the same U-shape pattern, first slowly decreasing during post-adolescence until the age of 30, 40, and 50 years, respectively, then progressively increasing until late life. FA showed a reverse profile, initially increasing then continuously decreasing, slowly until the 70s, then sharply declining thereafter. By contrast, PSMD constantly increased, first slowly until the 60s, then more sharply. These results demonstrate that, in the general population, age affects PSMD in a manner different from that of other DTI metrics. The constant increase in PSMD throughout the entire adult life, including during post-adolescence, indicates that PSMD could be an early marker of the ageing process.
源自扩散加权成像（DWI）的白质水扩散参数，如分数各向异性（FA）、平均扩散率、轴向扩散率和径向扩散率（MD、AD和RD），以及最近提出的骨架化平均扩散率峰值宽度（PSMD），已被视为正常和病理性脑老化的潜在标志物。然而，在健康个体的整个成年期，这些参数在成年早期和晚期的相对变化情况仍部分未知，对于PSMD指数尤其如此。在此，我们收集并分析了来自10项基于人群的队列研究的横断面扩散张量成像（DTI）数据，以确定从青春期后期到成年晚期白质水扩散表型的时间进程。DTI数据来自总共20005名年龄在18.1至92.6岁之间的个体，并使用相同的流程从DTI图计算骨架化DTI指标。对于每个个体，在其FA体积骨架上计算MD、AD、RD和FA的平均值，PSMD计算为FA骨架上MD值分布的90%峰值宽度。发现每个DTI指标的平均值在不同队列之间差异很大，这很可能是由于DWI采集协议以及预处理和DTI模型拟合存在重大差异。然而，发现年龄对每个DTI指标的影响在不同队列中高度一致。RD、MD和AD随年龄的变化呈现相同的U形模式，在青春期后期分别直到30岁、40岁和50岁时首先缓慢下降，然后逐渐增加直至老年。FA呈现相反的趋势，最初增加然后持续下降，直到70多岁时下降缓慢，此后急剧下降。相比之下，PSMD持续增加，直到60多岁时增加缓慢，之后增加更为明显。这些结果表明，在一般人群中，年龄对PSMD的影响方式与其他DTI指标不同。PSMD在整个成年期，包括青春期后期持续增加，表明PSMD可能是衰老过程的早期标志物。
