title: The trajectory of life. Decreasing physiological network complexity through changing fractal patterns.
abstract: In this position paper, we submit a synthesis of theoretical models based on physiology, non-equilibrium thermodynamics, and non-linear time-series analysis. Based on an understanding of the human organism as a system of interconnected complex adaptive systems, we seek to examine the relationship between health, complexity, variability, and entropy production, as it might be useful to help understand aging, and improve care for patients. We observe the trajectory of life is characterized by the growth, plateauing and subsequent loss of adaptive function of organ systems, associated with loss of functioning and coordination of systems. Understanding development and aging requires the examination of interdependence among these organ systems. Increasing evidence suggests network interconnectedness and complexity can be captured/measured/associated with the degree and complexity of healthy biologic rhythm variability (e.g., heart and respiratory rate variability). We review physiological mechanisms linking the omics, arousal/stress systems, immune function, and mitochondrial bioenergetics; highlighting their interdependence in normal physiological function and aging. We argue that aging, known to be characterized by a loss of variability, is manifested at multiple scales, within functional units at the small scale, and reflected by diagnostic features at the larger scale. While still controversial and under investigation, it appears conceivable that the integrity of whole body complexity may be, at least partially, reflected in the degree and variability of intrinsic biologic rhythms, which we believe are related to overall system complexity that may be a defining feature of health and it's loss through aging. Harnessing this information for the development of therapeutic and preventative strategies may hold an opportunity to significantly improve the health of our patients across the trajectory of life.
authors.affiliation: Faculty of Health and Medicine, School of Medicine and Public Health, The University of Newcastle Wamberal, NSW, Australia.
authors.forename: Joachim P
authors.initials: JP
authors.lastname: Sturmberg
authors.affiliation: Department of Psychology, The University of North Carolina at Charlotte Charlotte, NC, USA.
authors.forename: Jeanette M
authors.initials: JM
authors.lastname: Bennett
authors.affiliation: Center for Mitochondrial and Epigenomic Medicine, Children's Hospital of Philadelphia and the University of Pennsylvania Philadelphia, PA, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Picard
authors.affiliation: Thoracic Surgery and Critical Care Medicine, University of Ottawa and Associate Scientist, Ottawa Hospital Research Institute Ottawa, ON, Canada.
authors.forename: Andrew J E
authors.initials: AJ
authors.lastname: Seely
keywords: aging; bioenergetics; heart rate variability; inflammation; mitochondria; physiological networks; psychoneuroimmunology