Medical demography and epidemiology: dizygotic twins.

Demography is the statistical study of populations, epidemiology of health of populations. Fascinating challenges for future research, shared by epidemiology and demography, are to be found in the human life course, how the life course is transmitted over generations, how the healthy life is shaped by dynamics within the life course and how the life course is affected by the social and economic environment. The life course begins when two future parents meet. Then social disadvantage or privilege is beginning and diverse rates of ageing are being fixed. Health in utero and at young age will co-determine health at middle and old age, among others mediated by a greater intelligence and a better education. Particularly better education compresses cognitive disability at the end of life, building cognitive reserves that increase brain plasticity and enhance resistance to damage. While with extended life spans may come extended life spans with disability, the twin demography and epidemiology may show how to lighten the burden of senescence at the end of life.