Why Does Aging Vary Among Individuals?

Aging isn’t solely a product of time. Earlier views considered it a uniform process impacting the entire body simultaneously. However, recent findings suggest aging is highly unpredictable and starts at different times across body parts—possibly even earlier than we realize.

Aging also occurs uniquely at a molecular level in each person, and some aspects may be under our control. By understanding how our organs age, we might be able to slow or accelerate this process through lifestyle changes.

Organ-Specific Aging

Using advanced molecular biology, genetics, and big data, scientists analyze blood samples to determine if individuals experience "cardiac aging" (where the heart ages faster than other organs) or "brain aging" (where the brain shows more aging than the body). Some may even experience "brain youthfulness," meaning their brain ages slower than other organs. Similarly, muscle or liver aging can also vary.

Almost every organ can show signs of aging earlier than others, significantly impacting overall health. A Stanford study on organ aging revealed that people with cardiac aging are more prone to heart failure, while those with younger brains have an 80% lower risk of dementia later in life compared to those with an average or older brain.

Biological Age vs. Chronological Age

These findings reveal that aging is far less predictable than we think. Traditionally, age has been calculated based on birth year. However, scientists have long sought to refine "biological age"—a measure of how well the body functions. Biological age can differ from chronological age, being either higher or lower.

Implications for Health Decisions

Understanding one’s organ aging can guide health-related decisions. For example, someone with a rapidly aging heart might need more frequent cardiac tests and lifestyle adjustments in diet and exercise.

Although blood tests to determine organ aging are not yet available, researchers believe such screenings could become a standard part of annual health checkups in the future. For now, these advancements are expected to take years to become widely accessible.