Unitary psychosis (Einheitspsychose): A conceptual history.

Aims: The objective of this paper is to explore the evolution of the forms of madness and the model that accounts for it over time. The classical distinction between several categories of mental disorders is contrasted with the idea of unitary psychosis.

Methods: Historical conceptual analysis. The concept of unitary psychosis is explored in its basic features. Its origins in the nineteenth century and developments during the twentieth century are considered.

Results: Following the publication of Kraepelin's fundamental handbook, the debate was shaped as pro or against the Kraepelinian dichotomy between dementia praecox and manic-depressive illness. However, the origins of the concept of unitary psychosis as well as some more recent developments are independent from it.

Conclusions: This article argues that, when viewed pragmatically, both positions (the pluralist and the unitary) bring advantages that can be complementary rather than mutually exclusive. The pluralist position allows us to recognize the qualitative differences between phenomena and structures of experience, while the unitary model prevents us from reifying them. This is achieved by paying attention to the diachronic evolution and the pathogenetic dynamics.