ABSTRACT
Medical textbooks do not consider including chapters on “the mentally healthy” or on “mechanisms
of health.” Yet virtually every textbook on neurodegenerative dementia includes an obligatory
chapter on “healthy brain aging.” The goal may be to set healthy brain aging apart from dementia,
but it remains to be determined whether these two states comprise a dichotomy or a continuum. The
aging process itself is the most potent risk factor for most common dementing illness, and it has
been suggested (but not proven) that dementia may be an inevitable consequence of aging.
