Although the idea of aging evokes thoughts of the elderly, aging occurs in every stage of life, mysteriously transforming newborns into nanas. Surprisingly, for a universal biological process, the study of aging remains a field in its youth.
Why does a queen bee live for one year and a worker bee for a month?
Why does a catfish live for 60 years and a cat for 20?
Why does a mouse live for 2 years, a bat for 50 and a whale for 200?
These questions may or may not be interesting to you. However why some 60 year olds look and function more like a 40 year old, probably is.
The need to answer such questions has become more pressing as increased lifespan has created an unprecedented burden of disease and disability. By 2050, the world population aged 80 and above will more than triple, approaching 400 million. This global graying has stimulated a similar growth in aging research.
The questions posed above really ask why some age faster than others. Rate of living theories date back to Aristotle but a great leap forward occurred recently when specific gene mutations were shown to extend lifespan. Evolutionarily conserved signaling pathways that regulate metabolism, growth, reproduction and nutrient sensing appear to determine longevity.
(In my next entry I will discuss how these pathways are affected by lifestyle and a variety of drugs.)
From age 40 onward, advancing age is associated with an exponential increase in chronic disease. Most aging research has studied the elderly, who already suffer from age-related disease. The utility of identifying accelerated aging is to mitigate this deterioration and extend healthspan. Therefore the target population for diagnosing accelerated aging is the young.
Over the past decade meaningful biomarkers of aging in younger populations (people in their 30s) have been identified. Statistical analysis of these markers reflects physiological change relative to the passage of time, the pace of aging. Biological age calculations assess one point in time only and are therefore less informative than pace of aging that incorporates data from multiple time points.
A pervasive feature of aging and age-related disease is inflammation. The importance of this association is reflected in the neologism, inflammaging.
Rising levels of biomarkers associated with this chronic, low-grade, systemic inflammation indicate age-related deterioration in body composition (fat/muscle), energy production and utilization, metabolic equilibrium, immune and neurological function. Many of the tests used for determining pace of aging relate to inflammation.
The tests listed below represent a comprehensive battery used for research purposes. Most of them are not part of a standard medical exam. This will change as medicine slowly transitions from treating illness to preventing it. In the meantime, remember that you are the most important member of your health team. How you age is largely up to you.
Tests by Category
C-reactive protein, White blood cell count (WBC), Adiponectin, Interleukin-6, Interleukin-1beta, Tumor necrosis factor-alpha, Periodontal disease
Forced expiratory volume in one second (FEV1)
Forced vital capacity ratio (FEV1/FVC)
Cardiorespiratory fitness (VO2Max)
Leukocyte telomere length (LTL)
Total cholesterol, HDL, LDL
Lipoprotein(a), Apolipoprotein B100/A1 ratio
Body Composition/Fat distribution
Dual Energy X-Ray Absorpitometry (DXA)
Fat mass index (FMI)
Standing balance test
Chair rise speed