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Age- and sex-related effects on the neuroanatomy of healthy elderly

Moreover, one's labour market status may be expected to have a (reverse) causal effect on current and future health. In this paper we analyse the relative importance of these endogeneity and measurement issues in the context of a model of early retirement decisions. We state assumptions under which we can use relatively simple methods to assess the relative importance of state dependent reporting errors in individual responses to health questions. The estimation results indicate that among respondents. | NeuroImage ELSEVIER www.elsevier.com locate ynimg NeuroImage 26 2005 900-911 Age- and sex-related effects on the neuroanatomy of healthy elderly Herve Lemaĩtre a Fabrice Crivello a Blandine Grassiot a Annick Alperovitch b Christophe Tzourio b and Bernard Mazoyera c d Groupe d lmagerie Neurofonctionnelle UMR 6194 CNRS CEA Universites de Caen et Paris 5 GIP Cyceron BP5229 F-14074 Caen France bINSERM U360 Hopital Pitie-Salpetriere 75013 Paris France cUnite IRM CHU de Caen 14000 Caen France dInstitut Universitaire de France 75005 Paris France Received 16 December 2004 revised 4 February 2005 accepted 24 February 2005 Available online 13 April 2005 Effects of age and sex and their interaction on the structural brain anatomy of healthy elderly were assessed thanks to a cross-sectional study of a cohort of 662 subjects aged from 63 to 75 years. T1- and T2-weighted MRI scans were acquired in each subject and further processed using a voxel-based approach that was optimized for the identification of the cerebrospinal fluid CSF compartment. Analysis of covariance revealed a classical neuroanatomy sexual dimorphism men exhibiting larger gray matter GM white matter WM and CSF compartment volumes together with larger WM and CSF fractions whereas women showed larger GM fraction. GM and WM were found to significantly decrease with age while CSF volume significantly increased. Tissue probability map analysis showed that the highest rates of GM atrophy in this age range were localized in primary cortices the angular and superior parietal gyri the orbital part of the prefrontal cortex and in the hippocampal region. There was no significant interaction between Sex and Age for any of the tissue volumes as well as for any of the tissue probability maps. These findings indicate that brain atrophy during the seventh and eighth decades of life is ubiquitous and proceeds at a rate that is not modulated by Sex . 2005 Elsevier Inc. All rights reserved. Keywords Brain Aging Sex Voxel-based .