Mortality

Biological Factors

Epidemiologists study the effects of disease on mortality risk. Identifying how advanced the disease is at diagnosis, as well as tracking the further progression of disease, is important when estimating how long an individual may have left to live. For example, to determine mortality risk, researchers and clinicians examine white blood cell counts among those diagnosed with human immunodeficiency virus and cell growth in cancer patients.

In fact, several widely used biomarkers are useful when studying longevity (longevity representing the opposite of mortality). Biomarkers are objective indices of physiological processes occurring within the body. These biomarkers are used to determine how advanced a disease is, which also helps to approximate how long an individual has left to live. Common biomarkers used today are telomere length (indicative of cell replication senescence) and a host of immune parameters (e.g., Interleukin 6 and C-reactive protein). Dozens of physiological indicators are now being investigated as possible indicators of underlying aging processes and longevity.

Physical, Cognitive, and Socioemotional Factors

It is no surprise that physical functioning would be associated with mortality risk. Ample research has shown that individuals with better functional health are more likely to live longer and have a better quality of life. Self-rated physical health is actually one of the strongest predictors of health and longevity, with some researchers arguing that a person’s perception of his or her physical health is a better marker of health than objective physician reports. Another aspect of physical functioning, sensory function, has recently emerged as an [Page 1440]important predictor of mortality risk. Hypotheses suggest that declines in sensory function (e.g., sharp declines in vision and hearing) are indicative of developmental processes associated with the dying process.

The association between cognitive function and mortality risk has received significant attention from researchers, based on early studies finding that sharp declines in cognitive abilities were a precursor to impending death. However, cognitive abilities are also important early in life as research has shown childhood intelligence levels are predictive of longevity. One of the reasons cognitive ability has received so much research and mainstream media attention is because cognition is a modifiable skill that can be a point of intervention. Increasing years of education earlier in the life span is one way to improve cognitive abilities and longevity, but there has been growth in cognitive training programs designed for older adults because they are considered a potential mechanism for staving off cognitive declines and decreasing mortality risk. The success associated with these cognitive training programs has been mixed, but the fact remains that cognitive ability is an important predictor of mortality risk.

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