Aging

Background

Aging is the progressive decline of the human body’s function that results from a combination of genetic, environmental, and metabolic factors. As our cells accumulate damage, important systemic processes within the body become dysregulated, leading to an increased rate of disease and mortality (see overview here).

The global population is aging at an unprecedented rate, a phenomenon that carries significant social and economic challenges. Societies are investing heavily in the fight against aging—a recent analysis revealed that a slowdown of aging by just one year could be worth $38T in the US alone.

What Happens to the Body

As we age, our cells accumulate damage on many fronts, including mutations in DNA (the information code of our cells), shortening of telomeres (protective end caps on DNA strands), and epigenetic alterations (changes in how our cells read DNA information).

This causes our microscopic machinery to go awry. The result is decreased cellular function, impaired mitochondrial energy production, and less efficient repair mechanisms. Read more about the causes of cellular aging. 

As our body’s building blocks break down, our organs and tissues experience an associated loss of structure and function. This results in a cycle of inflammation and tissue fibrosis that reduces the functional capacity of our vital organs.

All of these microscopic changes add up to what we see as “getting older.” Our bones lose the ability to resist stress (i.e., osteoporosis), the structural integrity of our skin fails (i.e., wrinkles), our heart no longer pumps with the necessary strength (i.e., heart failure), and we are more at risk of injury and disease. 

What Happens to the Brain

The same cellular- and tissue-level changes associated with aging have a particularly destructive effect on our brains. 

As cellular function decreases, inflammation rises and the accumulation of cellular waste disrupts the ability of our brain cells to talk to each other. This impairs our processing of complex cognitive tasks and weakens our memory (what happens to your brain through life). 

These neurologic changes often translate to depression, social withdrawal, and increased susceptibility to diseases like Alzheimer’s and Parkinson’s dementia.

Chronological Versus Biological Aging

While the most familiar convention of measuring age is "chronological" (that is, measuring age in years), there is an emerging interest in determining "biological age."

This method uses formulas or blood test results to estimate the cellular age of a person. In other words, biological age is not a function of time but rather of how well cellular and organ systems are functioning in each individual. In this way, interventions such as exercise, healthy lifestyles, and perhaps even medications could reverse one’s biological age—all while their chronological age increases. 

While some testable biomarkers have emerged as candidates (e.g., the epigenetic clock), there is ongoing research to uncover simple, reliable means to measure and track one's biological age over time.

Lifespan Versus Healthspan

While tremendous recent progress has been made in the field of aging, the emphasis has begun to shift from extending lifespan (the number of years one is alive) to maximizing an individual’s healthspan (the number of years one is active and without disease).

Researchers emphasize a holistic approach to nurturing your healthspan, including consistent daily movement and exercise, high-quality sleep hygiene, a balanced diet with whole foods, and more.