Evidence for Dependence Among Diseases
Demographic calculations evaluating the role of chronic diseases in life expectancy use the assumption that diseases are independent. Disease independence was a plausible hypothesis in the era of infectious diseases. However, the health problems of modern populations are closely connected with diseases of the elderly i.e., with chronic non-communicable diseases that often have common risk factors. The existence of such common genetic and non-genetic risk factors makes chronic diseases mutually dependent. In this chapter, we provide evidence of trade-offs between cancer and other diseases as well as between cancer and aging changes. The Multiple Cause of Death data are used to evaluate correlations among mortality rules from cancer and other major health disorders, including heart disease, stroke, diabetes, Alzheimer’s and Parkinson’s diseases, and asthma. Significant negative correlations between cancer and some of the selected diseases are detected. These correlations show regular patterns of change over time. The chapter describes possible mechanisms of disease dependence including pleiotropic effects of genetic factors and discusses appropriate methods of statistical analysis of disease dependence.
