Simple-type schizophrenia is a sub-type of schizophrenia included in the International Classification of Diseases (ICD-10), in which it is classified as a mental and behaviour disorder. It is not included in the current Diagnostic and Statistical Manual of Mental Disorders (DSM-5) or the upcoming ICD-11, effective on the 1st of January 2022. Simple-type schizophrenia is characterized by negative ("deficit") symptoms, such as avolition, apathy, anhedonia, reduced affect display, lack of initiative, lack of motivation, low activity; with absence of hallucinations or delusions of any kind. Simple schizophrenia was included as a proposed diagnosis for further study in the appendix of the former DSM-IV. Signs and symptoms
It has possibly the earliest onset compared to all other schizophrenias, considered to begin in some within childhood. Symptoms of schizophrenia simplex include an absence of will, impoverished thinking and flattening of affect. There is a gradual deterioration of functioning with increased amotivation and reduced socialization. It is considered to be rarely diagnosed and is a schizophrenia without psychotic symptoms.In a study of patients in a Massachusetts hospital, persons with simple schizophrenia were found to make attempts at reality fulfillment with respect to the more primitive needs; tending toward the achievement of fulfillment of these needs rather than engaging in fantasy as is typically found as a reaction to environmental stimuli by the psychotic person. Causes
A progressive state of simple schizophrenia results often in cases of adolescent onset juvenile general paresis. Paresis is caused by placental-foetal transfer of infection and results in intellectual (mental) subnormality.
In 1860, Bénédict Morel introduced the term dementia précoce and Langdon Down provided  in 1887 the most complete description to that date of the clinical manifestation that Charpentier described in 1890 as dementia précoce simple des enfant normaux.The description of simple schizophrenia is inter-changeable with describing symptoms as a form of dementia praecox known as simple dementing, at least in the time when the Swiss psychiatrists Otto Diem and Eugen Bleuler were studying it. In 1893, Emil Kraepelin considered there were four types of schizophrenia, and was amongst the first to identify three of them (dementia hebephrenica, dementia paranoides, dementia catatonica). The simplex type was added by Eugen Bleuler to the earlier ones identified by Kraepelin in 1899 and subsequently given a basic outline in 1903 by Otto Diem publishing a monograph on dementia praecox in the simple dementing form. This was based on a survey of two males having had a relatively normal childhood but who then fell into patterns of living tending towards vagrancy.A description of a cerebral disorder in relation to organic factors and in the context of general paralysis of the insane only; with no reference to schizophrenia, shows a disorder with features of generalized dementia (Lishman 1998). In 1951, a film was made showing the clinical characteristics of simple-type schizophrenia. Controversy
Definition of this type of schizophrenia is without unity or is controversial. The diagnosis was discontinued in the DSM system, although it was recommended for reinclusion in 1989.