An array of technologies for preventing and treating age-related neural decline and disease are currently under development. A clear framework for how to identify groups in need of such inventions is needed. An encompassing concept of frailty could provide a solid basis for such purposes. Concepts of frailty, including physical and cognitive frailty, are currently applied in clinical settings, and in research and development. The terminology facilitates identifying processes of age-related physical and cognitive decline. However, age-related neurodegenerative diseases do not fit the conceptual framework of frailty. A terminology of frailty can and should be developed that connects aging, cognitive decline, and neurodegenerative disease. Such a framework needs to (a) adequately account for the effects that the processes of aging have on neural decline and disease, and (b) be helpful in identifying relevant groups of users and patients.