Age-related slowing of memory retrieval: Contributions of perceptual speed and cerebral white matter integrity

Center for the Study of Aging and Human Development, Duke University Medical Center, USA.
Neurobiology of aging (Impact Factor: 5.01). 08/2008; 29(7):1070-9. DOI: 10.1016/j.neurobiolaging.2007.02.008
Source: PubMed


Previous research suggests that, in reaction time (RT) measures of episodic memory retrieval, the unique effects of adult age are relatively small compared to the effects aging shares with more elementary abilities such as perceptual speed. Little is known, however, regarding the mechanisms of perceptual speed. We used diffusion tensor imaging (DTI) to test the hypothesis that white matter integrity, as indexed by fractional anisotropy (FA), serves as one mechanism of perceptual slowing in episodic memory retrieval. Results indicated that declines in FA in the pericallosal frontal region and in the genu of the corpus callosum, but not in other regions, mediated the relationship between perceptual speed and episodic retrieval RT. This relation held, though to a different degree, for both hits and correct rejections. These findings suggest that white matter integrity in prefrontal regions is one mechanism underlying the relation between individual differences in perceptual speed and episodic retrieval.

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    • "structures that are important to the efficiency of interhemispheric communication, and are linked to perceptual speed (Bucur et al. 2008) and cognitive decline in aging (Lövdén et al. 2010). Finally, cluster 5 included portions of the thalamus, a major relay of information not only between the periphery and the cortex, but also between cortical areas (Sherman 2007). "
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    • "Prior work suggests that DTI may provide information about different pathophysiological processes and may be one of the most sensitive neuroimaging biomarkers of vascular damage [35], [36], [37], [8]. Although, FA is the most widely studied diffusion metric, there is a growing interest in investigating WM microstructural mechanism underlying the FA change by analyzing other – more direct – diffusion metrics, such as axial (AD) and radial (RD) diffusivity. "
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