Cognitive Reserve? Cognitive Capacity!

The concept of cognitive reserve (CR) has been a cornerstone in cognitive aging research, offering a framework to explain how life experiences like education, occupation, bilingualism, and physical exercise may buffer individuals from cognitive decline in the face of aging or neurological disease. However, this paper argues that the CR model, while influential, may have outlived its usefulness due to inherent limitations that constrain future research directions and unintentionally encourage "magical thinking". Specifically, CR's definition, which relies on cognitive performance being "better than expected" based on known measures of brain structure and function, makes the concept temporally bound to current scientific understanding, potentially stifling novel insights into cognition. In contrast, we propose a shift to a cognitive capacity (CC) framework, which views cognitive performance as being always determined by the brain's structural and functional capacities, without needing to invoke expectations based on incomplete knowledge. The CC framework is broader, encompassing factors that either promote or demote cognitive performance by directly modifying brain structure and function. This reconceptualization opens avenues for investigating cognitive enhancement not only in the context of aging or disease but also in young, healthy individuals. By emphasizing causal pathways between brain changes and cognitive outcomes, this perspective provides a more flexible and testable approach to understanding the mechanisms behind cognitive performance and its modulation across the lifespan.