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Current Gerontology and Geriatrics Research
Volume 2012, Article ID 818564, 10 pages
Review Article

On the Dynamics of Active Aging

ERGO/European Research Institute on Health and Aging; Department of Psychology, University of Groningen, 9712 TS Groningen, The Netherlands

Received 31 May 2012; Accepted 30 July 2012

Academic Editor: Rocío Fernández-Ballesteros

Copyright © 2012 Johannes J. F. Schroots. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The conceptual basis of active aging is extended with a dynamic systems model, called Janus. The Janus model accounts for the life-course dynamics of simple and more complex growth and decline functions, on the strength of three principles. The first principle of transition states that the unitary lifespan trajectory of development and aging is the product of two complementary forces, growth and senescence, which are effective from conception until death. The first principle solves the traditional problem of the age at which development ends and the process of aging starts. The second and third principles of peak capacity and peak time refer, respectively, to the impact of growth rate (peak capacity) and rate of senescence (peak time) on the life-course of dynamic systems. The validity of the Janus model is demonstrated by simulating the empirical lifespan trajectories of functional capacity, intelligence, and mortality. The Janus model contributes to the concept of active aging by underlining the dynamic limits of human nature, by stimulating effective policies for promoting active aging in the first half of life, and by emphasizing the growth potential of older people in the second half.