Occurrence of this type of paresis is altogether uncommon (Lishman 1998). Diagnosis
Classification
ICD
The WHO first listed the condition in the 6th revision of the International Classification of Diseases ICD-6 (1949) and it stayed in the manual until the present version ICD-10. ICD-9
The ICD-9 simple-type schizophrenia description:

A psychosis in which there is insidious development of oddities of conduct, inability to meet the demands of society, and decline in total performance. Delusions and hallucinations are not in evidence and the condition is less obviously psychotic than are the hebephrenic, catatonic and paranoid types of schizophrenia. With increasing social impoverishment vagrancy may ensue and the patient becomes self-absorbed, idle and aimless. Because the schizophrenic symptoms are not clear-cut, diagnosis of this form should be made sparingly, if at all. ICD-10
These are the current criteria:

Slowly progressive development over a period of at least one year, of all three of the following: 
(a) A significant and consistent change in the overall quality of some aspects of personal behaviour, manifest as loss of drive and interests, aimlessness, idleness, a self-absorbed attitude and social withdrawal. (b) Gradual appearance and deepening of negative symptoms such as marked apathy, paucity of speech, underactivity, blunting of affect, passivity and lack of initiative, and poor non-verbal communication. (c) Marked decline in social, scholastic or occupational performance. 2. Absence, at any time, of any symptoms referred to in G1 in F20.0 - F20.3 and of hallucinations or well formed delusions of any kind, i.e.
The provisional research criteria for it were:

Progressive development over a period of at least a year of all of the following:
(1) marked decline in occupational or academic functioning
(2) gradual appearance and deepening of negative 
symptoms such as affective flattening, alogia, and avolition
(3) poor interpersonal rapport, social isolation or social withdrawal
B. Criterion A for Schizophrenia has never been met. C. The symptoms are not better accounted for by Schizotypal or Schizoid Personality Disorder, a Psychotic Disorder, a Mood Disorder, an Anxiety Disorder, a dementia, or Mental Retardation and are not due to the direct physiological effects of a substance or a general medical condition. Treatment
The use of antipsychotic medication is commonly the first line of treatment; however, the effectiveness after treatment is in question. L-DOPA is effective against reduced affect display and emotional withdrawal, aloofness from society, apathy. History
The early idea that a person with schizophrenia might present solely with symptoms and indications of deterioration (i.e. presenting with no accessory symptoms) was identified as dementia simplex.ICD-10 specifies the continuation of symptoms for a period of two years in the diagnosis of simple schizophrenia. This is because of disagreement on the classification validity of the sub-type, that having been retained by the ICD classification, has been omitted from DSM classifications. Symptoms identified earlier to dementia simplex are now DSM-attributed by way of improvements in diagnostic technique to other classifications such as neurodegenerative disorders.Early observations that concur with symptoms of the dementia praecox of the form classified later as simplex began in 1838 with Jean Esquirol.