A new definition of brain reserve.

Brain reserve definitions foster debate and disagreements. A consensus definition of brain reserve would fill gaps in converging ongoing research and action plans to promote brain health. Different terms are used for the capacity to adapt to life hardships and cognitive and social compliance and to neutralize or compensate for age-related neurological degeneration to prevent impaired cognition. Brain reserve, resilience, cognitive reserve, and brain maintenance have been used usually in isolation, but at times interchangeably. However, the need remains for a simplified overarching definition of brain reserve. Brain health is a continuous development and exercise of the brain, and thus the brain reserve requires a definition encompassing this continuum. We propose for discussion a new definition of brain reserve that incorporates available definitions and emphasizes the dynamic and interactive nature of a healthy brain. Brain reserve is the lifelong, dynamic, interactive, accumulating capacity to resist physical, emotional, and/or social harms.