BrainAGE in superagers: cross-sectional and longitudinal analyses in older adults aged 80+ with youthful episodic memory

Episodic memory, the ability to recall past events, is particularly vulnerable to ageing. A decline in episodic memory performance is generally considered part of ageing. However, the episodic memory performance of superagers -defined as individuals aged 80+ years old with episodic memory of people 30 years younger- is superior to that typical of their chronological age. The aim of this study was to determine whether the discrepancy between the superager's episodic memory and chronological age is also evident in their brain age. A BrainAGE (Brain Age Gap Estimation) approach, a multidimensional computational neuroanatomical method that uses structural neuroimaging data to estimate biological brain age, was applied. The study population comprised 64 superagers (mean age = 81.9 ± 1.9) and 55 age-matched typical older adults (82.4 ± 1.9). Cross-sectional analyses revealed a negative BrainAGE score for superagers (mean = -0.95 ± 2.36) indicating a deceleration of the ageing process. By contrast, typical older adults showed an average score close to zero (0.05 ± 3.03) consistent with their chronological age. The BrainAGE score of superagers was found to be lower relative to typical older adults, and the progression over a 5-year follow-up period was slower in superagers, in keeping with their youthful memory ability. Therefore, superagers have a younger brain than those of typical older adults, suggesting that their ageing mechanisms may involve resistance to age-related brain structural changes. However, despite a 30-year gap in episodic memory, their BrainAGE score differed by only one year, indicating that factors beyond brain structure contribute to the superager phenotype.