title: Brain tissue volumes in the general population of the elderly: the AGES-Reykjavik study.
abstract: Imaging studies have reported conflicting findings on how brain structure differs with age and sex. This may be explained by discrepancies and limitations in study population and study design. We report a study on brain tissue volumes in one of the largest cohorts of individuals studied to date of subjects with high mean age (mean ± standard deviation (SD) 76 ± 6 years). These analyses are based on magnetic resonance imaging (MRI) scans acquired at baseline on 4303 non-demented elderly, and 367 who had a second MRI, on average 2.5 ± 0.2 years later. Tissue segmentation was performed with an automatic image analysis pipeline. Total brain parenchymal (TBP) volume decreased with increasing age while there was an increase in white matter hyperintensities (WMH) in both sexes. A reduction in both normal white matter (NWM)- and gray matter (GM) volume contributed to the brain shrinkage. After adjusting for intra-cranial volume, women had larger brain volumes compared to men (3.32%, p < 0.001) for TBP volume in the cross-sectional analysis. The longitudinal analysis showed a significant age-sex interaction in TBP volume with a greater rate of annual change in men (-0.70%, 95%CI: -0.78% to -0.63%) than women (-0.55%, 95%CI: -0.61% to -0.49%). The annual change in the cross-sectional data was approximately 40% less than the annual change in the longitudinal data and did not show significant age-sex interaction. The findings indicate that the cross-sectional data underestimate the rate of change in tissue volumes with age as the longitudinal data show greater rate of change in tissue volumes with age for all tissues.
authors: The Icelandic Heart Association, Kopavogur, Iceland.
authors: Sigurdur
authors: S
authors: Sigurdsson
authors: The Icelandic Heart Association, Kopavogur, Iceland.|The University of Iceland, Reykjavik, Iceland.
authors: Thor
authors: T
authors: Aspelund
authors: The Icelandic Heart Association, Kopavogur, Iceland.
authors: Lars
authors: L
authors: Forsberg
authors: Raforninn Inc, Reykjavik, Iceland.
authors: Jesper
authors: J
authors: Fredriksson
authors: The Icelandic Heart Association, Kopavogur, Iceland.
authors: Olafur
authors: O
authors: Kjartansson
authors: The Icelandic Heart Association, Kopavogur, Iceland.
authors: Bryndis
authors: B
authors: Oskarsdottir
authors: The Icelandic Heart Association, Kopavogur, Iceland.|The University of Iceland, Reykjavik, Iceland.
authors: Palmi V
authors: PV
authors: Jonsson
authors: The Icelandic Heart Association, Kopavogur, Iceland.
authors: Gudny
authors: G
authors: Eiriksdottir
authors: Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA.
authors: Tamara B
authors: TB
authors: Harris
authors: Biospective Inc, Montreal, Canada.
authors: Alex
authors: A
authors: Zijdenbos
authors: Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.
authors: Mark A
authors: MA
authors: van Buchem
authors: Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA.
authors: Lenore J
authors: LJ
authors: Launer
authors: The Icelandic Heart Association, Kopavogur, Iceland.|The University of Iceland, Reykjavik, Iceland.
authors: Vilmundur
authors: V
authors: Gudnason
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001284:Atrophy; D001921:Brain / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009929:Organ Size