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.
Similar to other adenocarcinoma, if this tumor is well differentiated (low grade) it will resemble the normal glandular structure. Poorly differentiated adenocarcinoma will not resemble the normal glands (high grade) and will be detected by seeing that they stain positive for mucin (which the glands produce). Adenocarcinoma can also be distinguished by staining for TTF-1, a cell marker for adenocarcinoma.As discussed previously, the category of adenocarcinoma includes are range of subtypes, and any one tumor tends to be heterogeneous in composition. Several major subtypes are currently recognized by the World Health Organization (WHO) and the International Association for the Study of Lung Cancer (IASLC) / American Thoracic Society (ATS) / European Respiratory Society (ERS): lepidic predominant adenocarcinoma, acinar predominant adenocarcinoma, papillary predominant adenocarcinoma, micropapillary predominant adenocarcinoma, solid predominant adenocarcinoma, and solid predominant with mucin production. In as many as 80% of these tumors, components of more than one subtype will be recognized. Surgically resected tumors should be classified by comprehensive histological subtyping, describing patterns of involvement in increments of 5%. The predominant histologic subtype is then used to classify the tumor overall. The predominant subtype is prognostic for survival after complete resection.To reveal the adenocarcinomatous lineage of the solid variant, demonstration of intracellular mucin production may be performed. Foci of squamous metaplasia and dysplasia may be present in the epithelium proximal to adenocarcinomas, but these are not the precursor lesions for this tumor. Rather, the precursor of peripheral adenocarcinomas has been termed atypical adenomatous hyperplasia (AAH).