Following a reduction in the number of deaths from infectious diseases during the past 100 years, most of the major causes of death in developed countries can be classified as degenerative diseases. These diseases, however, are not a simple by-product of the ageing process. Numerous studies have shown that there are significant spatial variations in the incidence of major degenerative diseases, suggesting that there must be something causing these geographical inequalities. To be more precise, there must be factors which are unevenly distributed over space which either result in spatial inequalities in the incidence of degenerative diseases or which influence a person's chances of surviving a degenerative disease once contracted. In either event, a correct identification of the factors might enable preventive measures to be taken to reduce mortality from degenerative diseases.