The natural history of preventive medicine,or breaking the chains of causation.

In the past the natural history of disease has shown chains of causation. With the acute diseases, these chains have usually been quite short and easily broken. With the chronic diseases of today, they are far longer and more complicated. Often they involve patterns of behaviour extending over half a lifetime. These patterns are, in turn, determined partly by genetic make-up, partly by family and social environment. The study of these chains necessitated both observation and social survey methods. The breaking of the chains entails the use of propaganda or mass education. By far the most effective educational agent is the spoken word, coming from someone held in respect. The most effective persuader is fear. In social medicine we can seldom plan large-scale experiments. We have to seize such opportunities as life presents. One such opportunity was the creation of the new towns after the war. It was found that good social planning yielded good results in terms of social satisfaction, and infant-mortality and psychosis rates. The prevention of neurosis is a more difficult matter. In administration and in politics resistance to learning from the experience of others is strong. The preventive medicine of the future will necessitate the teaching of common sense applied to human behaviour to extremely resistant audiences.