SAGE-Hindawi Access to Research Journal of Aging Research Volume 2011, Article ID 814096, 11 pages doi:10.4061/2011/814096 Review Article Pathways to Aging: The Mitochondrion at the Intersection of Biological and Psychosocial Sciences Martin Picard Department of Kinesiology and Physical Education, McGill University, 475 Pine Avenue, Montreal, QC, Canada H2W 1S4 Correspondence should be addressed to Martin Picard, martin.picard@mail.mcgill.ca Received 16 February 2011; Revised 11 May 2011; Accepted 11 July 2011 Academic Editor: Leonard W. Poon Copyright © 2011 Martin Picard. 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. Compelling evidence suggests that both biological and psychosocial factors impact the process of aging. However, our under- standing of the dynamic interplay among biological and psychosocial factors across the life course is still fragmentary. For example, it needs to be established how the interaction of individual factors (e.g., genetic and epigenetic endowment and personality), behavioral factors (e.g., physical activity, diet, and stress management), and psychosocial experiences (e.g., social support, well- being, socioeconomic status, and marriage) in perinatal, childhood, and adulthood inﬂuence health across the aging continuum. This paper aims to outline potential intersection points serving as an interface between biological and psychosocial factors, with an emphasis on the mitochondrion. Mitochondria are cellular organelles which play a critical role in cellular senescence. Both chronic exposure to psychosocial stress and genetic-based mitochondrial dysfunction have strikingly similar biological consequences; both predispose individuals to adverse age-related health disorders and early mortality. Exploring the interactive nature of the factors resulting in pathways to normal healthy aging, as well as those leading to morbidity and early mortality, will continue to enhance our ability to translate research into eﬀective practices that can be implemented throughout the life course to optimise the aging process. 1. Introduction Aging is the inescapable process by which individuals, from the age of about 30 years old onwards, gradually lose maximal functional capacity [1]. Some resilient individuals experience a slow decline lasting several decades, attaining ages past one hundred years old and more [2]. These are exceptional centenarians who experience minimal physical impairment [3] along with healthy minds and bodies [4, 5]. However, many individuals experience more rapid func- tional declines in their 60’s or 70’s, sometimes aﬄicted with the “frailty syndrome”—deﬁned as a lack in general strength and unusual susceptibility to disease or to other inﬁrmity [6]—and these individuals often suﬀer from multiple age- related morbidities such as cardiovascular disease, neurode- generative diseases, diabetes, and cancer [7]. The majority of individuals lie between these two extreme scenarios, with an average life expectancy of 81 years old in North America [8]. In the past century, we have witnessed signiﬁcant increases in life expectancy as more individuals live longer [9, 10]. This increase in average life expectancy has undoubt- edly resulted from advances in medical technologies and preventive medicine that prevent most (>80%) early deaths due to acute illnesses (e.g., infections and injuries) and pro- long life of individuals aﬄicted with chronic life-threaten- ing conditions (e.g., HIV/AIDS and cardiovascular disease) [10]. The outcome of eﬀectively delaying mortality is that morbidity is postponed—or “compressed”—to older ages, as described in Fries’ compression of morbidity hypothesis [11]. The incidence of age-related diseases has remained stable over the last decades, or even increased, which signiﬁ-cantly contributes to health care costs [10]. Given that an un- precedentedly large proportion of the population is expected to reach 60–80 years of age in the next two decades [12], changes in political and social health policy will be necessary to face societal challenges [10, 13]. Comprehensive frame- works including the panoply of factors capable of potently modulating the human aging process may be essential to address the impending social imperative of implementing health-enhancing strategies for the elderly, at minimal costs.