PT - JOURNAL ARTICLE AU - S. Inano AU - H. Takao AU - N. Hayashi AU - O. Abe AU - K. Ohtomo TI - Effects of Age and Gender on White Matter Integrity AID - 10.3174/ajnr.A2785 DP - 2011 Dec 01 TA - American Journal of Neuroradiology PG - 2103--2109 VI - 32 IP - 11 4099 - http://www.ajnr.org/content/32/11/2103.short 4100 - http://www.ajnr.org/content/32/11/2103.full SO - Am. J. Neuroradiol.2011 Dec 01; 32 AB - BACKGROUND AND PURPOSE: DTI provides a sensitive measure of change in the microstructure of white matter integrity. The purpose of our study was to investigate age-related changes, sex differences, and age-by-sex interactions in white matter integrity (FA, AD, and RD) across the whole brain with a large sample. MATERIALS AND METHODS: A total of 857 healthy subjects (mean age = 56.1 ± 9.9 years; age range = 24.9–84.8 years) were included in this study. All subjects were scanned at 3T. With use of TBSS, we examined the effects of age and sex on FA, AD, and RD in the white matter. RESULTS: Global FA was negatively correlated with age (R2 = 0.18, P < .0001), and global AD and RD were positively correlated with age (AD: R2 = 0.02, P < .0001; RD: R2 = 0.19, P < .0001). The correlation between age and global AD, however, was weak. Voxelwise analysis revealed a number of regions where FA was negatively correlated with age, with most of these regions showing a significant positive correlation between RD and age. There was a significant age-related FA increase in several white matter regions. Voxelwise analysis also revealed many regions where FA, AD, or RD differed between men and women; however, no region showed a significant interaction between age and sex. CONCLUSIONS: Our results suggest that age-related changes in white matter integrity are more strongly associated with myelin sheath degeneration than with axonal degeneration, and that, in some specific regions, the number of remyelinated axons might increase with age. Our results also suggest that there are no sex differences in the aging process of the white matter. ADaxial diffusivityANCOVAanalysis of covarianceASSETarray spatial sensitivity encoding techniqueBETBrain Extraction ToolFAfractional anisotropyFDTFMRIB's Diffusion ToolboxFNIRTFMRIB's nonlinear registration toolFSLFMRIB Software LibraryFWEfamily-wise errorMDmean diffusivityMMSEMini-Mental State ExaminationMNIMontreal Neurological InstituteRDradial diffusivityTBSStract-based spatial statistics