Sluggish schizophrenia in the modern classification of mental illness.

The concept of latent schizophrenia was developed by E. Bleuler (1911) and was further promoted in the studies of a number of research psychiatric schools of Europe, the United States, Japan, and other countries. In Soviet psychiatry, there is a long-established tradition of studying "soft" forms of schizophrenia (Kerbikov 1933; Rozenshtein 1933; Brukhanskii 1934). In the systematics of schizophrenia, developed by Snezhnevsky (1969) and his colleagues, sluggish schizophrenia is viewed not as an initial (prodromal) stage of schizophrenia, but rather an independent diagnostic category characterized by a slowly progressive course, subclinical manifestations in the latent period, overt psychopathological symptoms in the active period, and then by a gradual reduction of positive symptoms, with negative symptoms predominating the clinical picture during patient stabilization. Studies are reviewed examining the relationship of constitutional and genetic factors to the clinical manifestation of sluggish schizophrenia. Finally, the importance of methodological considerations and an examination of divergent factors in the U.S. and Soviet concepts of schizophrenia are presented.