Aging as a Process of Complexity Loss

Healthy physiologic function requires the integration of complex networks of control systems and feedback loops that operate on multiple scales in space and time. When measured continuously, the output of physiologic systems is highly complex, resulting in dynamic behavior that can be described using techniques derived from fractal analysis. These fractal-like physiologic processes enable an organism to adapt to the exigencies of everyday life. During normal human aging the degeneration of various tissues and organs, and the interruption of communication pathways between them, results in a loss of complexity of physiologic systems and, consequently, a reduced capacity to adapt to stress. Therefore, relatively minor perturbations such as new medications, a viral illness, or emotional trauma may result in serious disability and death. Fortunately, a number of novel interventions may be able to restore healthy dynamics in elderly individuals and enhance their ability to adapt to a variety of external stimuli.