Functional phenotyping of successful aging in long‐term memory: Preserved performance in the absence of neural compensation

Abstract

We investigated whether preservation of encoding-related brain activity patterns in older age reflects successful aging in long-term memory. Using a statistical matching technique, we identified groups of healthy older adults with different degrees of Functional Activity Deviation during Encoding (FADE) from young adults in a memory network comprising hippocampal, temporal, occipital, and retrosplenial regions. High FADE scores were associated with impairment in recollection, abnormal activity in the default mode network, and lower gray matter density in bilateral ventral prefrontal cortex and left rhinal cortex; a constellation previously associated with increased risk for dementia. Low FADE scores functionally phenotyped successful aging because recollection was well preserved and there was no evidence for compensatory prefrontal activation. Thus, for some individuals successful aging in long-term memory reflects the preservation of a functionally specific memory network, and can occur in the absence of compensatory brain activity.

Better together: Left and right hemisphere engagement to reduce age-related memory loss

“…Furthermore, a third set of imaging data suggested that young and elderly participants with high performance on cognitive tasks recruited a similar network of brain regions [30][31][32]91]. These findings drew attention to brain maintenance hypothesis [15].…”

“…Another pattern of imaging findings described similar networks of brain regions recruited by younger and high-performing older adults [15,[30][31][32] and leaded to discuss that the lack of functional changes could constitute a determinant of successful memory aging.…”

The cognitive neuroscience of ageing

“…In young adults, DN regions maintain strong functional interconnections during tasks requiring self-reference or theory of mind 101,102 , and also during the resting state 103,104 . Several studies have found that the reduction of DN activity during externally-driven cognitive tasks is less pronounced in old adults, relative to young adults 58,[105][106][107][108][109][110][111][112] . Functional connectivity of the DN also is reduced with age during working memory tasks 113 and during periods of rest 105,[114][115][116] .…”

Age differences in default and reward networks during processing of personally relevant information

“…Several studies have found that the reduction of DN activity during externally-driven cognitive tasks is less pronounced in older adults, relative to younger adults (Andrews-Hanna et al, 2007;Damoiseaux et al, 2008;Duzel, Schutze, Yonelinas, & Heinze, 2011;Esposito et al, 2008;Grady et al, 2010;Grady, Springer, Hongwanishkul, McIntosh, & Winocur, 2006;Lustig et al, 2003;Miller et al, 2008;Persson, Lustig, Nelson, & Reuter-Lorenz, 2007). Intrinsic functional connectivity within the DN during periods of rest also is reduced in older relative to younger adults (Andrews-Hanna, et al, 2007;Hedden et al, 2009;Park, Polk, Hebrank, & Jenkins, 2010), and age reductions during memory tasks also have been noted (Sambataro et al, 2010;Wang, Li, Metzak, He, & Woodward, 2010).…”