Does senescence give rise to disease?

Abstract

The distinctions between senescence and disease are blurred in the literature of evolutionary biology, biodemography, biogerontology and medicine. Theories of senescence that have emerged over the past several decades are based on the concepts that organisms are a byproduct of imperfect structural designs built with imperfect materials and maintained by imperfect processes. Senescence is a complex mixture of processes rather than a monolithic process. Senescence and disease have overlapping biological consequences. Senescence gives rise to disease, but disease does not give rise to senescence. Current data indicate that treatment of disease can delay the age of death but there are no convincing data that these interventions alter senescence. An understanding of these basic tenets suggests that there are biological limits to duration of life and the life expectancy of populations and reveal biological domains where the development of interventions and/or treatments may modulate senescence.

Fig. 1

Senescence viewed as a mixture of stochastic and non-stochastic effects and the influence of age on those effects.

Fig. 2

Schematic illustrating the relationship of observed life span to potential life span and the difference between interventions that reclaim survival time as opposed to those that extend survival by modifying senescence.