Chronological, Biological, and Functional Age

Several recent conversations have involved the concept of “age.” In order for these conversations to continue and be fruitful, it is necessary to look at three of the ways in which age can be defined. The conversations have also involved the concepts of “weathering”  and  “high effort coping.” The first of these introduces the idea that African Americans, as a population, age biologically at a faster rate than whites.  The second concept is used in attempts to explain why striving to succeed against the odds can also result in illness and/or more rapid aging. This is not an attempt to review the literature. It is an attempt to point toward the literature that needs to be reviewed.


Chronological Age

When people say that “age ain’t nothing but a number” they are speaking of chronological age, which is a measure of age based on the calendar date of a person’s birth. Chronological age is usually given in the number of years that a person has lived. Chronological age can also include months and days.

Chronological Age Calculator

Biological or Physiological Age

Chronological age may be a simple series of numbers. Biological age tends to be a more complex issue.

Biological aging concerns a number of processes in the human body that, over time, result in reduced adaptability, disease, physical and functional declines, disability, and ultimately death.

It is extremely important to understand that  people age at different rates biologically. This means that people who share a chronological age can be of different biological ages.

In one study researchers used 18 different biomarkers to examine the health of the pulmonary,  peridontal, cardiovascular,  renal, hepatic, and immune systems of approximately 1000 participants at ages 26, 32, and 38. While most participants had biological ages that were similiar to their chronological ages some study participants aged as much as three years physiologically over the course of one calendar year. The rate at which a person ages biologically is generally considered to be the result of the interaction between genetic/epigenetic, environmental (social and physical) and lifestyle factors.

    Belsky, D. W., Caspi, A., Houts, R., Cohen, H. J., Corcoran, D. L., Danese, A., … Moffitt, T. E. (2015). Quantification of biological aging in young adults. Proceedings of the National Academy of Sciences of the United States of America, 112(30), E4104–E4110.


Functional Age

The concept of functional age is used in several speciaties The field of most concern here is physical or rehabilitation medicine. In this field functional age refers to both cardiovascular and musculoskeletal fitness and the type of activities in which a person can engage and for how long when compared to other people of similiar chronological age. Functional age also refers to the abilities and limitations that a person encounters in carrying out the activities of daily living.


The term ‘weathering”  ( was introduced into the research literature  to suggest that African Americans experience premature biological aging and earlier health decline than whites.  A recent report from the CDC calls this hypothesis to mind


by pointing out that African Americans are more likely to live with or die from conditions like heart disease, stroke, and diabetes at much younger chronological ages than whites.  


Sojourner Syndrome and John Henryism

There are enough studies on how “high effort coping” has a negative impact on the health of African Americans that many people understand the expressions “Sojourner Syndrome” and “John Henryism” as well as the attempts to create instruments to measure them.

…decades of research show that when resilient people work hard within a system that has not afforded them the same opportunities as others, their physical health deteriorates.

As health deteriorates, biological aging out paces chronological aging.


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