Cognitive reserve and adaptive resilience: a conceptual analysis of a cross-species framework for neuropsychology and cognitive aging.

Why do some older adults maintain effective cognitive functioning despite substantial age-related brain change or neuropathology, whereas others with comparable neural burden show marked impairment? Related questions arise in comparative research, where organisms exposed to similar biological or environmental challenges may show markedly different adaptation patterns. Although these phenomena have traditionally been examined in separate literatures, they converge on a broader problem: how living systems maintain, recover, or reorganize function under challenge. This article develops a cross-species conceptual framework linking research on adaptive resilience with contemporary models of cognitive reserve and cognitive aging. The proposed contribution is not to redefine cognitive reserve as dynamic or lifespan-based, features already recognized in current reserve theory, but to identify a set of candidate mechanisms through which reserve-related capacities may be developed and expressed. We organize these mechanisms across four interacting domains: biological regulation, behavioral flexibility, social regulation, and environmental engagement and enrichment. These processes are hypothesized to contribute, across development and aging, to the capacity to adapt when biological or environmental demands increase. A fifth domain, functional preservation and recovery, represents the outcome of these processes rather than cognitive reserve itself. In humans, preserved cognition despite neural burden may therefore be understood as a cognitive-resilience phenotype to which cognitive reserve, brain maintenance, compensation, and related mechanisms can contribute. Nonhuman animal models do not possess cognitive reserve in its human clinical sense, but they provide experimental access to potentially conserved mechanisms involving stress regulation, flexible responding, social buffering, learning, and experience-dependent plasticity. Cognitive reserve remains the primary translational focus of the present framework because of its central role in cognitive aging and dementia research, while recognizing that related mechanisms may also operate in affective, motor, behavioral, and neuroautonomic domains. The framework generates testable predictions about how measurable adaptive processes may complement traditional reserve proxies and improve understanding of individual differences in cognitive aging.