Conclusion

All the above concurrent evidences show how it is still difficult to identify the causes of the time-related-changes in human being that we call aging. Today we think more in term of longevity and functioning that in term of aging. For example we consider that longevity and efficient functions were shaped through evolution and selection not aging. But most of the concepts that we are still using today were built around the concept of aging. This is the case for intrinsic and extrinsic aging, as well as “normal” (define as the non-diseased aging - 56), “aging in apparent good health” (57) and pathological aging. The definitions of these concepts are still unsatisfactory. Moreover, these definitions have to better integrate the heterogeneity of aging at the individual level as well as at the population level. The most recent and comprehensive concepts are:

-          The “usual” or “average” aging that includes substantial physiological losses and psychological or stressful events increasing the risk for disease and disability with advancing age (56).

-                      The “successful” aging that corresponds classically to the combination of low probability of disease, high functioning level and active engagement with life (58). Successful aging is a worldwide concept, but it remains difficult to identify among such a heterogeneous variety of human beings, the indicators which could universally characterize elderly persons as successfully aged. In a public health perspective, successful aging is defined as “a state of well being”, but most elderly persons themselves view “success in aging” rather as “a process of adaptation” to new life situations (59). Personally, as geriatricians, we consider that the concept of “successful” aging intrinsically includes, whatever the physical and functional states, a high feeling of “good self esteem” and “life satisfaction”.

Acknowledgements:

The authors would like to thank Mr. Bernard GRAB and Pr. Ezio GIACOBINI for their valuable contributions to the editing of this paper.

Key words: aging, genetics, reactive oxygen species, risk factors, activity of daily living