The classification of psychiatric illnesses was essentially based on stage theory, the idea that a given illness progressed from stage to stage. This was in contrast to the Kraepelinian scheme of classifying illnesses – with the exception of manic-depressive illness – on the basis of current phenomenology. According to the previous stage theories such as Zeller, Magnan and Griesinger, a major illness would typically begin with a mood picture (mania or melancholia), transition into psychosis (Verrücktheit, délire), then transition again in dementia. This illness course tended to be life-long, the order of the stages invariant (rarely was psychosis seen as the primary disorder, or did dementia yield to yet another stage). These concepts would be innovative in terms of the DSM system, which recognizes stage theory only in bipolar disorder.

To clarify the nature of linear illness pictures (‘stage theory’) in a psychiatric presentation.

To revive a traditional psychiatric concept of the linear illness entity (‘stage theory’) in the interest of improved diagnosis and treatment

An analysis of the large past psychiatric literature in French, German, Italian, and English

The illness courses of many past patients do seem to have unfolded in stages.

Stage theory stemmed from senior clinicians of vast experience, whose ideas were are not entitled patronizingly to dismiss. The DSM system is now under assault and it may be time to reassess the usefulness of stage theory.