Cognitively elite, cognitively normal, and cognitively impaired aging: neurocognitive status and stability moderate memory performance.

OBJECTIVE: Although recent theories of brain and cognitive aging distinguish between normal, exceptional, and impaired groups, further empirical evidence is required. We adapted and applied standard procedures for classifying groups of cognitively impaired (CI) and cognitively normal (CN) older adults to a third classification: cognitively healthy, exceptional, or elite (CE) aging. We then examined concurrent and two-wave longitudinal performance on composite variables of episodic, semantic, and working memory.
METHOD: We began with a two-wave source sample from the Victoria Longitudinal Study (VLS; source n = 570; baseline age = 53-90 years). The goals were to: (a) apply standard and objective classification procedures to discriminate three cognitive status groups, (b) conduct baseline comparisons of memory performance, (c) develop two-wave status stability and change subgroups, and (d) compare of stability subgroup differences in memory performance and change.
RESULTS: As expected, the CE group performed best on all three memory composites. Similarly, expected status stability effects were observed: (a) stable CE and CN groups performed memory tasks better than their unstable counterparts, and (b) the stable (and chronic) CI group performed worse than its unstable (variable) counterpart. These stability group differences were maintained over two waves.
CONCLUSION: New data validate the expectations that (a) objective clinical classification procedures for cognitive impairment can be adapted for detecting cognitively advantaged older adults, and (b) performance in three memory systems is predictably related to the tripartite classification.