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Age-related changes of Peak width Skeletonized Mean Diffusivity (PSMD) across the adult life span: A multi-cohort study

Research output: Contribution to journalArticle

  • Gregory Beaudet
  • Ami Tsuchida
  • Laurent Petit
  • Christophe Tzourio
  • Svenja Caspers
  • Jan Schreiber
  • Zdenka Pausova
  • Yash Patel
  • Tomas Paus
  • Reinhold Schmidt
  • Lukas Pirpamer
  • Perminder S Sachdev
  • Henry Brodaty
  • Nicole A. Kochan
  • Julian N. Trollor
  • Wei Wen
  • Nicola J Armstrong
  • A. Veronica Witte
  • Arno Villringer
  • Marco Duering
  • Stephanie Debette
  • Bernard Mazoyer

Related Edinburgh Organisations

Original languageEnglish
JournalFrontiers in psychiatry
Publication statusAccepted/In press - 6 Apr 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, respectively, then progressively increasing until late life. FA showed a reverse profile, initially increasing
then continuously decreasing, slowly until the 70’s, then sharply declining thereafter. By contrast, PSMD constantly increased, first
slowly until the 60’s, 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.

    Research areas

  • ageing, diffusion MRI, PSMD, small vessel disease, white matter

ID: 142696869