HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Cited by other online articles Google Scholar Articles by Lipsitz, L. A. Articles citing this Article PubMed PubMed Citation Articles by Lipsitz, L. A.

Dynamics of Stability

The Physiologic Basis of Functional Health and Frailty

^a Hebrew Rehabilitation Center for Aged, Beth Israel Deaconess Medical Center, and Harvard Medical School Division on Aging, Boston, Massachusetts

Lewis A. Lipsitz, Hebrew Rehabilitation Center for Aged, 1200 Centre Street, Boston, MA 02131 E-mail: Lipsitz{at}mail.hrca.harvard.edu.

Decision Editor: John A. Faulkner, PhD

Under basal resting conditions most healthy physiologic systems demonstrate highly irregular, complex dynamics that represent interacting regulatory processes operating over multiple time scales. These processes prime the organism for an adaptive response, making it ready and able to react to sudden physiologic stresses. When the organism is perturbed or deviates from a given set of boundary conditions, most physiologic systems evoke closed-loop responses that operate over relatively short periods of time to restore the organism to equilibrium. This transiently alters the dynamics to a less complex, dominant response mode, which is denoted "reactive tuning." Aging and disease are associated with a loss of complexity in resting dynamics and maladaptive responses to perturbations. These alterations in the dynamics of physiologic systems lead to functional decline and frailty. Nonlinear mathematical techniques that quantify physiologic dynamics may predict the onset of frailty, and interventions aimed toward restoring healthy dynamics may prevent functional decline.

This article has been cited by other articles: (Search Google Scholar for Other Citing Articles)

				L. P. Fried, E. C. Hadley, J. D. Walston, A. B. Newman, J. M. Guralnik, S. Studenski, T. B. Harris, W. B. Ershler, and L. Ferrucci From Bedside to Bench: Research Agenda for Frailty Sci. Aging Knowl. Environ., August 3, 2005; 2005(31): pe24 - pe24. [Abstract] [Full Text]

				M. M. Sturman, D. E. Vaillancourt, and D. M. Corcos Effects of Aging on the Regularity of Physiological Tremor J Neurophysiol, June 1, 2005; 93(6): 3064 - 3074. [Abstract] [Full Text] [PDF]

				L. A. Lipsitz Physiological Complexity, Aging, and the Path to Frailty Sci. Aging Knowl. Environ., April 21, 2004; 2004(16): pe16 - pe16. [Abstract] [Full Text]

				J. Walston Frailty--The Search For Underlying Causes Sci. Aging Knowl. Environ., January 28, 2004; 2004(4): pe4 - 4. [Abstract] [Full Text]

				J. J. Sosnoff, D. E. Vaillancourt, and K. M. Newell Aging and Rhythmical Force Output: Loss of Adaptive Control of Multiple Neural Oscillators J Neurophysiol, January 1, 2004; 91(1): 172 - 181. [Abstract] [Full Text]

				S. H. Tariq MD KNOWLEDGE ABOUT LOW TESTOSTERONE IN OLDER MEN J. Gerontol. A Biol. Sci. Med. Sci., April 1, 2003; 58(4): M382 - 383. [Full Text] [PDF]

				W. A. Banks and J. E. Morley Memories Are Made of This: Recent Advances in Understanding Cognitive Impairments and Dementia J. Gerontol. A Biol. Sci. Med. Sci., April 1, 2003; 58(4): M314 - 321. [Full Text] [PDF]

				H. T. Blumenthal The Aging-Disease Dichotomy: True or False? J. Gerontol. A Biol. Sci. Med. Sci., February 1, 2003; 58(2): M138 - 145. [Full Text] [PDF]

				J. E. Morley, H. M. Perry III, and D. K. Miller Editorial: Something About Frailty J. Gerontol. A Biol. Sci. Med. Sci., November 1, 2002; 57(11): M698 - 704. [Full Text] [PDF]