Age-related alterations in white matter microstructure measured by diffusion tensor imaging. Neurobiol Aging

MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA 02129-2060, USA.
Neurobiology of Aging (Impact Factor: 5.01). 08/2005; 26(8):1215-27. DOI: 10.1016/j.neurobiolaging.2004.09.017
Source: PubMed


Cerebral white matter (WM) undergoes various degenerative changes with normal aging, including decreases in myelin density and alterations in myelin structure. We acquired whole-head, high-resolution diffusion tensor images (DTI) in 38 participants across the adult age span. Maps of fractional anisotropy (FA), a measure of WM microstructure, were calculated for each participant to determine whether particular fiber systems of the brain are preferentially vulnerable to WM degeneration. Regional FA measures were estimated from nine regions of interest in each hemisphere and from the genu and splenium of the corpus callosum (CC). The results showed significant age-related decline in FA in frontal WM, the posterior limb of the internal capsule (PLIC), and the genu of the CC. In contrast, temporal and posterior WM was relatively preserved. These findings suggest that WM alterations are variable throughout the brain and that particular fiber populations within prefrontal region and PLIC are most vulnerable to age-related degeneration.

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    • "Gray matter volume and cortical thickness decrease globally with advancing age (Good et al., 2001; Resnick et al., 2003) with these effects most evident in prefrontal regions (Resnick et al., 2003; Salat et al., 2004, 2005b). Studies of white matter microstructural integrity (i.e., diffusion tensor imaging ; DTI) have found the most consistent effects using measures of fractional anisotropy (FA) in the prefrontal cortex (Bennett et al., 2010; Burgmans et al., 2010; Pfefferbaum et al., 2000; Salat et al., 2005a) and the genu of the corpus callosum (Bennett et al., 2010; Burgmans et al., 2010; Kochunov et al., 2012; Pfefferbaum et al., 2000; Salat et al., 2005a; Voineskos et al., 2012; Zahr et al., 2009), which connects the right and left prefrontal cortices (Hofer and Frahm, 2006). These regions are involved in higher-order executive functions, such as working memory and response inhibition (Zahr et al., 2009), which also show age-related declines (Park et al., 2002). "
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    • "Brain white matter structure in older age can be investigated using imaging biomarkers derived from diffusion tensor MRI (DT-MRI), such as fractional anisotropy (FA) and mean diffusivity (MD) (Salat et al. 2005; Sullivan and Pfefferbaum 2006). Although ascribing these biomarkers directly to white matter 'integrity' is problematic (Jones et al. 2013), a number of authors have used them to investigate links between brain structure and processing speed in older age. "
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    • "Effects of aging on white matter integrity are pronounced and have been well-documented in the literature (Abe et al., 2008; Hsu et al., 2008; Nusbaum et al., 2001; Pfefferbaum et al., 2000; Salat et al., 2005; Sullivan et al., 2001). Fractional anisotropy (FA) tends to decrease in most brain regions while mean diffusivity (MD) and radial diffusivity (RD) tend to increase with advancing age. "
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