[Results of experimental gerontology with respect to biological age].

Biological age may be defined as the state of the organism as a whole which is characteristic of the respective chronological age. Objective estimates of biological age are usually obtained by multiple regression analysis of a greater number of age parameters. However, this procedure should be based on a firm knowledge of the regularities of multicellular ageing. By means of a long-term study in male rats regularities of biological ageing have been demonstrated using multiple regression analysis, factor analysis and discriminant analysis. The multiple regression model pointed to an exponential relation between chronological and biological age. By factor analysis it has been shown that the change of the parameters represents to various extents primary ageing and system-specific secondary ageing. The results of discriminant analysis reveal a change in the ageing pattern during senescence. Consequently, test batteries for the objectivation of influences on the rate of ageing should be adapted to the respective phase of ageing in order to obtain maximum sensitivity.