title: Regional vulnerability of hippocampal subfields to aging measured by structural and diffusion MRI.
abstract: In the past few years, there has been an increasing awareness of the regional vulnerability of the hippocampus to age-related processes. However, to date, no studies have assessed the effects of age on different structural magnetic resonance parameters in the specific hippocampal subfields. In this study, we measured volume, mean diffusivity (MD) and fractional anisotropy (FA) in the presubiculum, subiculum, fimbria, cornu ammonis (CA) 1,2-3,4-DG and the whole hippocampus in fifty cognitively intact elder adults between 50 and 75 years of age (20 men, 30 women). Segmentation of hippocampal subfields was performed using FreeSurfer. Individual MD and FA images were coregistered to T1-weighted volumes using FLIRT of FSL. Linear regression analyses were performed to assess the effects of age on the anatomical measures of each subfield. In addition, multiple regression analyses were also carried out to assess which of the anatomical measures that showed a correlation with age in the previous analyses, were the best age predictors in the hippocampus. In agreement with previous studies, our results showed a significant association between age and volume (P < 0.001) as well as MD (P < 0.001) in the whole hippocampus. Regarding the specific hippocampal subfields, we found that age had a significant negative effect on volume in CA2-3 (P < 0.001) and CA4-DG (P < 0.001). Importantly, we found a positive effect of age on MD in CA2-3 (P < 0.001) and fimbria (P < 0.001) as well as a negative age effect on FA in the subiculum (P < 0.001). Multiple regression analyses revealed that the best overall predictors of age in the hippocampus were MD in the fimbria and volume of CA2-3, which explained 73.8% of the age variance. These results indicate that age has an effect both on volume and diffusion tensor imaging measures in different subfields, suggesting they provide complementary information on age-related processes in the hippocampus.
authors: Department of Psychiatry and Clinical Psychobiology, University of Barcelona, Spain; Institute of Biomedical Research August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden.
authors: Joana B
authors: JB
authors: Pereira
authors: Cinta
authors: C
authors: Valls-Pedret
authors: Emilio
authors: E
authors: Ros
authors: Eva
authors: E
authors: Palacios
authors: Carles
authors: C
authors: Falcón
authors: Nuria
authors: N
authors: Bargalló
authors: David
authors: D
authors: Bartrés-Faz
authors: Lars-Olof
authors: LO
authors: Wahlund
authors: Eric
authors: E
authors: Westman
authors: Carme
authors: C
authors: Junque
mesh_terms: D000368:Aged; D000375:Aging / Q000473:pathology*; D016880:Anisotropy; D003430:Cross-Sectional Studies; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009929:Organ Size
keywords: age; fractional anisotropy; hippocampus; mean diffusivity; volume