Table 1.

Conceptual positioning of the proposed adaptive-resilience framework relative to reserve and resilience constructs.

Construct	Primary focus	Temporal/ functional emphasis	Typical operationalization	Relation to proposed framework	References
Cognitive reserve	Better-than-expected cognition given life-course brain change/injury/disease; mechanisms may be molecular, cellular, network, or cognitive.	Active; influenced across the lifespan.	Education/IQ or other proxies; moderation; cognitive/neural experimental approaches.	Primary human translational target. Proposed cross-species processes are candidate contributors to its development/expression, not a redefinition of CR.	(Stern et al., 2020, 2023)
Cognitive resilience	Preserved/better-than-expected cognition despite adverse brain factors.	Outcome/phenotype under challenge; often longitudinal.	Moderation or residual/discrepancy methods, depending on framework.	Closest mapping to Level 5 cognitive outcome. Should not be conflated with CR.	(Kremen et al., 2022; Bocancea et al., 2021; Elman et al., 2022)
Brain reserve	Neurobiological capital/status.	Resource level at a point in time; not active adaptation.	Brain volume, neuronal/synaptic or related structural features.	Potential contributor to preserved function, but conceptually distinct from behavioral flexibility or regulation.	(Stern et al., 2023)
Brain maintenance	Relative preservation of neural resources/pathology over time.	Longitudinal preservation.	Change in brain markers linked to preserved cognition.	Parallel protective pathway; not the same as behavioral adaptation.	(Stern et al., 2023)
Compensation	Cognition-enhancing recruitment of neural resources under high demand or age-related loss.	Real-time/task-related response to demand.	Functional activation and performance patterns; selection, upregulation, reorganization.	One plausible mechanism through which adaptive behavior is expressed under neural challenge.	(Cabeza et al., 2018)
Affective reserve	Capacity to regulate affective states/dispositions across adversity, pathology, or aging.	Affective adaptation across the lifespan.	Emotion/motivation regulation, coping, social support; operationalization still developing.	Complementary domain-specific reserve; supports the claim that reserve need not be cognitively exclusive.	(Di Rosa, 2024)
Motor reserve	Preserved motor function despite disease-related neural burden.	Motor-system adaptation/compensation.	Physical activity and motor/neural measures; definitions still being standardized.	Complementary domain-specific reserve demonstrating outcome-specific reserve mechanisms.	(Giustiniani and Quartarone, 2024)
Behavioral reserve	Less severe behavioral disturbance than expected for neural burden, studied especially in bvFTD.	Behavioral phenotype under disease burden.	Behavior-neuroimaging discrepancy/residual-type approaches.	Shows that reserve-related phenomena can be expressed outside conventional cognitive outcomes.	(Kim et al., 2022)
Neuroautonomic Adaptive Resilience (NAR)	Dynamic self-regulatory coordination between central and autonomic nervous-system processes supporting adaptation to cognitive and emotional stressors.	Dynamic, real-time regulation across stress phases and lifespan.	HRV/EDA or related autonomic profiles.	Dynamic resilience mechanism positioned within biological regulation. It may interact with cognitive reserve, maintenance, and compensation but does not constitute a reserve mechanism itself.	(Fusi et al., 2026)
Proposed adaptive-resilience framework	Cross-species mechanisms linking life-course experience to adaptive functioning under challenge.	Developmental + dynamic; mechanisms and outcomes explicitly separated.	Biological regulation, behavioral flexibility, social regulation, environmental engagement, and functional preservation/recovery.	Adds a comparative mechanistic layer. Levels 1–4 are candidate pathways; Level 5 is functional outcome/resilience phenotype.	Present manuscript