title: Accelerated longitudinal gray/white matter contrast decline in aging in lightly myelinated cortical regions.
abstract: Highly myelinated cortical regions seem to develop early and are more robust to age-related decline. By use of different magnetic resonance imaging (MRI) measures such as contrast between T1- and T2-weighted MRI scans (T1w/T2w) it is now possible to assess correlates of myelin content in vivo. Further, previous studies indicate that gray/white matter contrast (GWC) become blurred as individuals' age, apparently reflecting age-related changes in myelin structure. Here we address whether longitudinal changes in GWC are dependent on initial myelin content within tissue as defined by baseline T1w/T2w contrast, and hypothesize that lightly myelinated regions undergo more decline longitudinally. A sample of 207 healthy adult participants (range: 20-84 years) was scanned twice (interscan interval: 3.6 years). Results showed widespread longitudinal reductions of GWC throughout the cortical surface, especially in the frontal cortices, mainly driven by intensity decay in the white matter. Annual rate of GWC blurring showed acceleration with age in temporal and medial prefrontal regions. Moreover, the anatomical distribution of increased rate of GWC decline with advancing age was strongly related to baseline levels of intracortical myelin. This study provides a first evidence of accelerated regional GWC blurring with advancing age, relates GWC patterns to cortical myeloarchitectonics and supports the hypothesis of increased age-related vulnerability of lightly myelinated areas. Hum Brain Mapp 37:3669-3684, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Research Group for Lifespan Changes in Brain and Cognition, Department of Psychology, University of Oslo, Oslo, Norway.
authors.forename: Didac
authors.initials: D
authors.lastname: Vidal-Piñeiro
authors.affiliation: Research Group for Lifespan Changes in Brain and Cognition, Department of Psychology, University of Oslo, Oslo, Norway.
authors.forename: Kristine B
authors.initials: KB
authors.lastname: Walhovd
authors.affiliation: Research Group for Lifespan Changes in Brain and Cognition, Department of Psychology, University of Oslo, Oslo, Norway.
authors.forename: Andreas B
authors.initials: AB
authors.lastname: Storsve
authors.affiliation: Research Group for Lifespan Changes in Brain and Cognition, Department of Psychology, University of Oslo, Oslo, Norway.
authors.forename: Håkon
authors.initials: H
authors.lastname: Grydeland
authors.affiliation: Research Group for Lifespan Changes in Brain and Cognition, Department of Psychology, University of Oslo, Oslo, Norway.
authors.forename: Darius A
authors.initials: DA
authors.lastname: Rohani
authors.affiliation: Research Group for Lifespan Changes in Brain and Cognition, Department of Psychology, University of Oslo, Oslo, Norway.
authors.forename: Anders M
authors.initials: AM
authors.lastname: Fjell
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology*; D002540:Cerebral Cortex / Q000000981:diagnostic imaging*; D005260:Female; D066128:Gray Matter / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009186:Myelin Sheath; D009929:Organ Size; D066127:White Matter / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: T1w/T2w; aging; gray/white matter contrast; lifespan; myelin