The diseases and disabilities of aging are caused by the accumulation of damage in our tissues over time. During our first two to three decades of life, developmental programs build out our growing bodies, laying down the cellular and molecular structures of our tissues in exquisite fidelity to the instructions carried in our genetic code. From form flows function: the pristine condition of the microscopic machinery of life ensures its silent, unimpeded functioning, manifested in the health and vigor of youth.
Most of us first begin to notice age-related decline in tissue function when we’re in our forties or fifties. The cushioning of our joints becomes thinner and weaker; our kidneys become progressively less effective at filtering our blood; our immune systems weaken, leaving us vulnerable to infections that we would once have dismissed with a few sniffs. Ultimately, minor aches and mysterious malaise devolve into clinical diagnoses. Atherosclerosis. Cataracts. Alzheimer’s and other dementias. Parkinson’s disease. Cancer. Why?
The fundamental drivers of degenerative aging lie in the biochemical and cellular side-effects of essential metabolic processes in the body. The business of life is carried out by intricate, interlocking, tightly-regulated cycles of biochemical reactions in our bodies – but these reactions have to be executed in the hurly-burly of living cells and tissues, rather than in the neat isolation of a laboratory Petri dish. Minor biochemical accidents are frequent and inevitable incidents in these cellular laboratories, and many of them cause microscopic damage to the structure of our tissues. In addition, our cells are sometimes forced to make “decisions” in response to immediate crises that ensure short-term function and survival, but that also contribute to the overall burden of damage in our tissues.
These myriad metabolic mistakes leave their mark in our tissues every day, but at such low levels that they are not individually noticed, and instead take many decades to build up to the levels where the tissues begin to cease proper functioning. Thinning skin, clouding eyes, muscles sapped of strength, heart disease, cognitive decline… all of the diseases and disabilities of aging flow from the inexorable degradation of the integrity of the cellular and molecular machinery that carries out the essential functions of our tissues. And as this process continues, the body’s increasingly-desperate attempts to repair or compensate for the rising tide of damage become chronic and maladaptive, leading to self-perpetuating inflammation, oxidative stress, and other secondary metabolic aberrations that further impair our health.