The cellular mechanisms that promote the maintenance of cognitive abilities in very old people designated as successful agers remain under-investigated. Here, we report an episodic memory performance-based criteria that differentiates superior cognitive function from normative cognitive function in adults aged 80 and older.
Objective
Using this new criteria, we demonstrate how neuropathological and neurobiological underpinnings of superior cognitive performance can be investigated.
Methods
The most recent verbal episodic memory WMS-R Logical Memory Delayed Recall (LM-DR) score was derived from 144 participants with no cognitive impairment (NCI) 80 years or older participants from the Rush Religious Orders Study classified with Superior Cognitive Performance (SCP, LM-DR ≥ 14) or Normal Cognitive Performance (NCP, LM-DR 13 ≥ 7). Both groups were compared on neuropathological measures for neuritic plaque (NP), diffuse plaque (DP), and neurofibrillary tangle (NFT) load.
Results
NP (p = 0.44), DP (p = 0.27), and NFT (p = 0.28) burden did not differ between SCP and NCP cases. LM-DR scores did not correlate with NP (r = −0.08, p = 0.32), DP (r = −0.14, p = 0.07), or NFT (r = −0.12, p = 0.13) load. Biochemical analysis revealed significantly higher levels of heat-shock protein HSPB6 in SCP compared to NCP (p < 0.001).
Conclusions
Heat shock protein differences were observed between NCP and SCP groups. This suggests that our proposed criteria for SCP can help identify neurobiological mechanisms of successful cognitive aging. Our SCP criteria are also concordant with the SuperAger criteria which supports the generalizability of the SCP criteria to other datasets.
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