Abstract
Previous studies have introduced the concept of “SuperAgers,” defined as older adults with youthful memory performance associated with the increased cortical thickness of the anterior cingulate cortex. Given that age-related structural brain changes are observed earlier in the white matter (WM) than in the cortical areas, we investigated whether WM integrity is different between the SuperAgers (SA) and typical agers (TA) and whether it is associated with superior memory performance as well as a healthy lifestyle. A total of 35 SA and 55 TA were recruited for this study. Further, 3.0-T magnetic resonance imaging (MRI), neuropsychological tests, and lifestyle factors related to cognitive function, such as physical activity and duration of sleep, were evaluated in all participants. SA was defined as individuals demonstrating the youthful performance of verbal and visual memory, as measured by the Seoul Verbal Learning Test (SVLT) and the Rey-Osterrieth Complex Figure Test (RCFT), respectively. Tract-based spatial statistics (TBSS) analysis was used to compare the diffusion values such as fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and axial diffusivity (AD) between the SA and TA. SA exhibited better performance in memory, attention, visuospatial, and frontal executive functions than the TA did. SA also exhibited greater amounts of physical activity than the TA did. As compared to TA, SA demonstrated higher FA with lower MD, RD, and AD in the corpus callosum and higher FA and lower RD in the right superior longitudinal fasciculus (SLF), which is significantly associated with memory function. Interestingly, FA values of the body of corpus callosum were correlated with the amount of physical activity. Our findings suggest that WM integrity of the corpus callosum is associated with superior memory function and a higher level of physical activities in SA compared to TA.
Highlights
Age-related cognitive decline is a common feature that occurs with age (Hedden and Gabrieli, 2004)
Given that white matter (WM) integrity declines progressively during normal aging, it could be more related to age-related cognitive decline than the cortical areas (Morrison and Hof, 1997), so it is important to investigate the topography of WM integrity in SuperAgers since preserved areas of the WM could be one of the most resilient areas in age-related cognitive decline (Madden et al, 2009)
We found that SuperAgers had greater WM integrity in the corpus callosum as well as the superior longitudinal fasciculus (SLF) and inferior longitudinal fasciculus (ILF) than the Typical Agers, which was associated with enhanced cognitive function as well as with the high amount of physical activity
Summary
Age-related cognitive decline is a common feature that occurs with age (Hedden and Gabrieli, 2004). Several neuroimaging studies have shown that the cortical thickness or volume in the anterior cingulate cortex of the SuperAgers is greater than that the average elderly population and similar to that in younger adults (Harrison et al, 2012; Rogalski et al, 2013; Gefen et al, 2015). Previous studies have shown that the loss of myelin integrity in the WM is considered to be one of the key mechanisms underlying normal age-related cognitive decline (Salat et al, 2005; Madden et al, 2008, 2012). Several neuroimaging studies have investigated cortical structures in SuperAgers (Harrison et al, 2012; Sun et al, 2016), to our knowledge, no studies have yet assessed WM integrity in SuperAgers
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