Published online by Cambridge University Press: 30 November 2019
Neuroimaging visualizes and quantifies age-related changes in brain structure, function, cerebral blood flow, and cerebral metabolic health. MRI studies show reductions in both overall and regional brain volumes, but to a lesser extent than in Alzheimer’s disease. Those aging non-pathologically tend to have relative preservation of mesial temporal and enthorhinal brain areas. White matter changes are also common as shown by hyperintensities on fluid attenuated inversion recovery and other T2 MRI images, presumably as a result of co-morbities that increasingly occur with age. Diffusion tensor imaging shows reductions in white matter integrity, including white matter fiber counts and overall white matter volume, beginning in mid- to late life. The neural response during both rest and task performance also shows reduced activation of core task-related networks but expansion to include other region activation. Reduced cerebral blood volume and flow also occur, likely reflecting alterations in hemodynamic function due to cerebrovascular and cardiovascular changes. Cerebral metabolic changes on MR spectroscopy occur with reduced concentrations of GABA and other neurotransmitters, as well as markers of neuronal integrity. Myoinositol, a marker of glial activation, may be elevated, indicating neuroinflammation, though this effect is likely not ubiquitous in successful aging.
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