Novel approaches to address cognitive aging and to delay or prevent cognitive decline in older individuals will require a better understanding of the biological and environmental factors that contribute to it. Studies in animal models—in particular, animals whose cognitive trajectory across their life span closely tracks that of humans—can provide important insights into the factors that contribute to the accumulation of reserve and ways in which it is preserved or depleted. A better understanding of the molecular processes that underlie these elements would enhance and guide not only research but also treatment approaches to these issues. These treatment approaches may include noninvasive brain stimulation and drug treatments to promote youthfulness or combat the aging process. It is important to realize, however, that these processes occur in the context of the human experience, and studies of them must consider the complexity and individuality of each person's life.