BACKGROUND: To assess the hypothesis that in a sample of very healthy elderly men selected to minimize risk for Alzheimer's disease (AD) and cerebrovascular disease, myelin breakdown in late-myelinating regions mediates age-related slowing in cognitive processing speed (CPS). MATERIALS AND METHODS: The prefrontal lobe white matter and the genu of the corpus callosum myelinate later in brain development (late-myelinating white matter; LMWM) and are more vulnerable to breakdown due to the effects of normal aging. An in vivo MRI biomarker of myelin integrity (transverse relaxation rates; R(2)) of LMWM was obtained for 38 very healthy elderly adult men (mean age=66.3 years; SD=6.0; range=55-76). To evaluate regional specificity, we also assessed a contrasting early-myelinating region (splenium of the corpus callosum; SWM), which primarily contains axons involved in visual processing. CPS was assessed using the Trail Making Test. RESULTS: LMWM R(2) and CPS measures were significantly correlated (r=.515, p=.0009), but no significant association between R(2) and CPS was detected in the splenium (p=.409). LMWM R(2), but not SWM R(2), was a significant mediator of the relationship between age and CPS (p=.037). CONCLUSIONS: In this very healthy elderly sample, age-related slowing in CPS is mediated by myelin breakdown in highly vulnerable late-myelinating regions but not in the splenium.
BACKGROUND: To assess the hypothesis that in a sample of very healthy elderly men selected to minimize risk for Alzheimer's disease (AD) and cerebrovascular disease, myelin breakdown in late-myelinating regions mediates age-related slowing in cognitive processing speed (CPS). MATERIALS AND METHODS: The prefrontal lobe white matter and the genu of the corpus callosum myelinate later in brain development (late-myelinating white matter; LMWM) and are more vulnerable to breakdown due to the effects of normal aging. An in vivo MRI biomarker of myelin integrity (transverse relaxation rates; R(2)) of LMWM was obtained for 38 very healthy elderly adult men (mean age=66.3 years; SD=6.0; range=55-76). To evaluate regional specificity, we also assessed a contrasting early-myelinating region (splenium of the corpus callosum; SWM), which primarily contains axons involved in visual processing. CPS was assessed using the Trail Making Test. RESULTS: LMWM R(2) and CPS measures were significantly correlated (r=.515, p=.0009), but no significant association between R(2) and CPS was detected in the splenium (p=.409). LMWM R(2), but not SWM R(2), was a significant mediator of the relationship between age and CPS (p=.037). CONCLUSIONS: In this very healthy elderly sample, age-related slowing in CPS is mediated by myelin breakdown in highly vulnerable late-myelinating regions but not in the splenium.
Authors: Ivonne Suridjan; Pablo M Rusjan; Miran Kenk; Nicolaas Paul L G Verhoeff; Aristotle N Voineskos; David Rotenberg; Alan A Wilson; Jeffrey H Meyer; Sylvain Houle; Romina Mizrahi Journal: Synapse Date: 2014-07-28 Impact factor: 2.562
Authors: Paola M Garcia-Egan; Rebecca N Preston-Campbell; Lauren E Salminen; Jodi M Heaps-Woodruff; Lila Balla; Ryan P Cabeen; David H Laidlaw; Thomas E Conturo; Robert H Paul Journal: Brain Imaging Behav Date: 2019-12 Impact factor: 3.978
Authors: Ashley M Behrman-Lay; Christina Usher; Thomas E Conturo; Stephen Correia; David H Laidlaw; Elizabeth M Lane; Jacob Bolzenius; Jodi M Heaps; Lauren E Salminen; Laurie M Baker; Ryan Cabeen; Erbil Akbudak; Xi Luo; Peisi Yan; Robert H Paul Journal: Brain Imaging Behav Date: 2015-12 Impact factor: 3.978
Authors: Erin O Wissler Gerdes; Yi Zhu; B Melanie Weigand; Utkarsh Tripathi; Terence C Burns; Tamar Tchkonia; James L Kirkland Journal: Int Rev Neurobiol Date: 2020-08-11 Impact factor: 3.230