講演者： 松下 貢（中央大学理工学部教授）
講演題目： Long-tailed Distributions of Duration of Life for Disability in Aged People - Revisit to Log-normal Distribution
Disability and the resulting lowered quality of life are serious issues accompanying increased longevity. Curiously, despite its potential contribution to aging theory, complete statistical and etiological structures of this common and unwelcome aging phenotype before death have not been well studied. Here we analyze characteristic long tails of the duration distributions for disabilities in the aged. Log-normal distribution (LND) shows excellent fit with various data on the durations of disabilities, irrespective of their severity. The robust long-tailed LND for various phases of disability validates the fact that patients in disability undergo series of stochastic subprocesses of many independent endogenous diseases, i.e., multiple pathology, until death. A declining force of natural selection after reproduction and trade-off of life history through pleiotropy of the genes are considered to be the roots of aging. The attenuated selection pressure and the resulting decrease of genetic constraints produce an increased opportunity for chance and stochastics. Now that we found surprizingly good application of LND above, we decided to revisit LND and its new applications. We would like to show several interesting datasets from various disciplines which are shown to fit excellently to LND, and then discuss the implication.