The development of the concept of reactive psychoses.

Although reactive (psychogenic) psychoses have no doubt occurred throughout the history of mankind, it is only during the last century that the corresponding concept has been defined, beginning with Sommer's definition of the term 'psychogenic' and Jaspers' distinctions between 'reaction' and 'process', and between 'neurosis' and 'psychosis', respectively. A change in Kurt Schneider's nosological concepts induced the majority of German-speaking psychiatrists to avoid the concept of psychogenic psychoses. The very varying use of the concept of reactive psychoses in different countries is described and discussed, with special regard to implications for psychiatric epidemiology.