Cognitively average elderly adults demonstrated greater annual whole-brain cortical volume loss over 18 months compared with SuperAgers, adults 80 years and older with memory ability at least as good as that of average middle-age adults, according to a study published by JAMA.
SuperAgers have a significantly thicker brain cortex than their same-age peers with average-for-age memory, which is unusual as age-related cortical atrophy is considered "normal" and often associated with cognitive decline in nondemented older adults. Amanda H. Cook, M.A., of Northwestern University, Chicago, and colleagues quantitated rates of cortical volume change over 18 months in 24 SuperAgers and 12 cognitively average elderly adults to examine if SuperAgers may resist age-related brain atrophy.
The researchers found that both groups demonstrated statistically significant average annual percent whole-brain cortical volume loss (SuperAgers, 1.06 percent; cognitively average elderly, 2.24 percent). However, the annual percentage change in whole-brain cortical volume loss was significantly greater in cognitively average elderly compared with SuperAgers.
The authors note that the possibility that SuperAgers were endowed with larger brains throughout life cannot be ruled out.
"As SuperAgers represent a rare cognitive phenotype, study findings require validation in larger samples with broader representation of demographic and socioeconomic features. The functional effect of the lesser decline of cortical volume in SuperAgers over 18 months is difficult to surmise. However, the between-group unadjusted difference in annual percentage change of 1.2 percent is similar in magnitude to the difference demonstrated in previous studies between nondemented and demented adults older than 50 years, suggesting that differences of this magnitude may have functional consequences. The factors that underlie the rate of age-related cortical volume loss are unknown; however, research on SuperAgers provides unique opportunities for exploring their biological foundations," the authors write.
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(doi:10.1001/jama.2017.0627; the study is available pre-embargo at the For the Media website)
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JAMA