Reply to “Limitations of Conclusions of Systematic Review & Meta‐analysis Due to Exclusion of Groups Most at Risk”

manifest. In active models, cognitive reserve is thought to compensate for brain damage by actively using various mechanisms such as recruiting preexisting cognitive networks, improving efficiency of brain processing, and enlisting compensatory brain networks. Activities that enhance muscle function may have modest effects on improving or maintaining cognitive function in aging, but this association does not equate to being a good measure of cognitive reserve. Under passive and active cognitive reserve models, muscle structure and biology are secondary to the underlying cognitive processes and brain substrates that may more directly contribute to cognitive reserve. Hence, although I agree that leisure activities that increase cognitive reserve should be explored as a delirium-preventive strategy, I do not agree that muscle function is a good proxy for characterizing cognitive reserve.