Functional age is a concept that was first introduced by one of my mentors, James E. Birren, PhD, in the 1960s (Birren, 1964).

Dr. Birren argued that a person’s functional age was more indicative of ability than chronologic age. Also, functional age can be controlled to some degree so that the aging process can be attenuated and many abilities of a young brain maintained throughout the lifespan.

While brain capacity diminishes after age 30, intellectual ability can continue to develop into late adulthood, given proper circumstances (Birren, 1988). I always consider this when people ask me if dementia is inevitable. If you live long enough, there is 50% likelihood that you will experience impaired cellular or vascular status involving your brain. This percentage increases if you have hypertension, diabetes, depression, smoke cigarettes, drink more than moderate amounts of alcohol, or retire to a life without daily challenges. The question then becomes whether the impaired cellular or vascular status leads to impaired function of your brain.

Dr. Birren would argue that this does not necessarily follow. While it is clear that brain capacity diminishes with age, mental ability does not need to diminish. Although we have dependable changes with age in the organic substrate of our brains, most functional decrements occur because we do not maintain adequate physical, mental, and spiritual health. Plus, there is a lot that we can do to improve brain health, even if we have these risk factors. We know that neuroplasticity and neurogenesis continue into older adulthood as long as the risk factors listed above are controlled.

In rehabilitation, we harness these processes to help people return to meaningful lives after a stroke or brain injury. The same processes can be used by older adults to attenuate typical age-based functional decrements. This has already been demonstrated with regard to safety in driving an automobile; the American Automobile Association has endorsed the use of computer-assisted brain training and provides discounts on premiums for older drivers who participate in this training.

So, take steps today to improve your functional age. Learn something new and challenging. Practice brain fitness with Posit Science or Lumosity. Always have a book to read and get exercise every day. Dr. Birren is 92 years old and going strong!

  • Birren, J. (1964). The psychology of aging. New Jersey: Prentice-Hall.
  • Birren, J. (1988). A contribution to the theory of aging: As a counterpart to development. In J. Birren & V. Bengston (Eds.), Emergent Theories of Aging (pp. 153–176). New York: Springer.