The incredible processes that enable our bodies to perform even the simplest of tasks boggle the mind of the layman- but our physiological processes become increasingly simple as we age.
Even seemingly simple bodily functions like heartbeat rely on interacting networks of metabolic controls, signaling pathways, genetic switches, and circadian rhythms. As our bodies age, these anatomic structures and physiologic processes lose complexity, making them less resilient and ultimately leading to frailty and disease.
A large and growing body of research suggests that biological complexity diminishes with aging, as various tissues and organs, and their communication pathways, gradually break down.
The fractal-like networks of tissue in our brains, bones, kidneys, and skin all lose structural complexity as we age. This loss impairs their capacity to adapt to stress, and may eventually lead to disease or disability. For example, when the microscopic struts in bone tissue thin and disconnect, as occurs with osteoporosis, bones become brittle and prone to fracturing. Likewise, the
pruning of neural connections in the brain is associated with age-related neurodegenerative disorders, such as Alzheimer’s and Parkinson’s diseases.
Physiologic processes, too, lose complexity with aging. Take, for instance, heart rate. Although average beats per minute may stay relatively constant over a person’s life span, tiny variations in the timing between beats become more regular (less complex) with advancing age. Numerous studies have linked this change to cardiac disease and mortality: The simpler the signal, the higher the likelihood of abnormal rhythms, heart attacks, and heart failure. Similarly, neural activity produces electrical signals that appear less complex in older adults. As complexity declines, so do motor control and cognitive functions, including gait, attention, and memory.