The researchers reported a “dramatic reduction” in functional connections when they compared the younger and older groups.
The researchers also used an MRI technique called “diffusion tensor imaging” to measure the integrity of white matter in the brains of the subjects. This technique reveals details of the structure of brain tissue. Their analysis revealed that the reduced functional connection they detected in brain areas of the older subjects was correlated with decreased white matter integrity.
When the researchers tested the subjects’ cognitive function, they found that “Those individuals exhibiting the lowest functional correlation also exhibited the poorest cognitive test scores.”
The researchers concluded that “our observations suggest that within the context of globally intact brain systems, subtle changes accumulate over time in advanced aging that disrupt the coordination of large-scale brain systems.”
They also said that, although AD is known to produce similar deterioration due to pathological deposits of amyloid protein, “Our present results, in particular the analysis of individuals without amyloid deposition, show that normal aging is associated with a form of system disruption that is distinct from that associated with AD.”
###
The researchers include Jessica R. Andrews-Hanna, of Harvard University, Cambridge, MA, USA, and Massachusetts General Hospital, Charlestown, MA, USA; Abraham Z. Snyder, of Washington University School of Medicine, St. Louis, MO, USA; Justin L. Vincent, of Harvard University, Cambridge, MA, USA, and Massachusetts General Hospital, Charlestown, MA, USA; Cindy Lustig, of University of Michigan, Ann Arbor, MI, USA; Denise Head, of Washington University School of Medicine and Washington University's Department of Psychology, St. Louis, MO, USA; Marcus E. Raichle, of Washington University School of Medicine, St. Louis, MO, USA; and Randy L. Buckner, of Harvard University, Cambridge, MA, USA, Massachusetts General Hospital, Charlestown, MA, USA, Harvard Medical School, Boston, MA, and Howard Hughes Medical Institute, Chevy Chase, MD, USA. |
