Differential Diagnosis. Beginning with DSM-III (Amercian Psychiatric Association, 1980, pp. 181-193) schizophrenia has been conceptualized as a "group of disorders" with probably differing etiologies. Note the distinct historical emphases on deterioration (Kraepelin), underlying psychological disturbances (Bleuler), and pathognomonic symptoms (Schneider) Under DSM-III-R (APA, 1987), Schizophrenia proper presumes a typical onset in late adolescence or early adulthood and a 6+ month duration, but "Schizophreniform Disorder" category does not
Latent, Borderline, or Simple Schizophrenias, lacking overt psychotic content, are labeled "Schizotypal Personality Disorder" on Axis II. If the affective symptoms are longer-lasting or earlier than the psychotic features, diagnosis should be Affective or Schizoaffective disorder [cont. UK-trained, tradeoffs w. affective diag's]
Content of thought. The major disturbance in the content of thought involves delusions that are often multiple, fragmented, or bizaare (i.e., patently absurd, with no possible basis in fact). Simple persecutory delusions involving the belief that others are spying on, spreading false rumors about, or planning harm to the individual are common. Delusions of reference, in which events, objects, or other people are given particular and unusual significance, usually of a negative or pejorative nature, are also common. For example, the individual may be convinced that a television commentator is mocking him.
Delusioins. Certain delusions are far more common in this disorder than in other psychotic disorders. These include, for instance, the belief or experience that one's thoughts, as they occur, are broadcast from one's head to the external world so that others can hear them (thought broadcasting); that thoughts that are not one's own are inserted into one's mind (thought insertion); that thoughts have been removed from one's head (thought withdrawal); or that one's feelings, thoughts, or actions are not one's own but are imposed by some external force (delusions of being controlled). Less commonly, somatic, grandiose, religious, and nihilistic delusions are seen. Overvalued ideas may occur (e.g., preoccupation with the special significance of certain dietary habits), or markedly illogical thinking (e.g., thinking that contains clear internal contradictions or in which conclusions are reached that are clearly erroneous, given the initial premises).
Form of thought. A disturbance in the form of thought is often present. This has been referred to as "formal thought disorder," and is distinguished from a disorder in the content of thought. The most common example of this is loosening of associations, in which ideas shift from one subject to another completely unrelated or only obliquely related subject, without the speaker showing any awareness that thetopics are unconnected. Statements that lack a meaningful relationship may be juxtaposed, or the individual may shift idiosyncratically from one frame of reference to another. When loosening of associations is severe, incoherence may occur, that is, speech may become incomprehensible. There may also be poverty of content of speech, in which speech is adequate in amount, but conveys little information because it is vague, overly abstract or averly concrete, repetetive, or stereotyped. The listener can recognize this disturbance by noting that little if any information has been conveyed although the individual has spoken at some length. Less common disturbances include neologisms, perseveration, clanging, and blocking.
Associated features. Note eccentricities of grooming and behavior, perplexity.
Course. Distinguish prodromal, active, residual phases
Kraepelin, E.  Dementia Praecox and Paraphrenia. New York: Robert E. Krieger, 1971.
Kraepelin (1855-1926) traced his own conception of Dementia Praecox (premature major deterioration of mental functioningt) as a distinct entity to 1896, and the place it occupied in his classic Text-Book of Psychiatry (a 40-year project reaching 2500 pages in its 8th edition) grew from 30 pages in the 5th edition to over 300 in the 8th.
The "praecox" refers to an adolescent or early adult onset of what Kraepelin believed to be a necessarily deteriorating condition (so that recovery implied misdiagnosis (cf. Freud-Jung letters). Kraepelin distinguished "catatonic," "hebephrenic," and "paranoid" subtypes.
Bleuler, E.  Dementia Praecox or the Group of Schizophrenias. New York: International Universities Press, 1950.
Note the dominance in Europe of Kraepelin's narrower, and in the US of Bleuler's broader, criteria.
Section I. "Fundamental" (Ch. 1) and "Accessary" (Ch. 2) symptoms:
The Four As: Association, Affectivity, Ambivalence, Autism
Section II. Subgroups: Paranoid, Catatonic, Hebephrenic, Simple
Bleuler's discussion of the problem of understanding Schizophrenic speech often seems to lose the forest for the trees, but is frequently close to the mark:
According to our present view, the distortions of speech which occur in schizophrenia are not to be differentiated from those which occur in dreams. ...
For the most part, words are so used as to designate an idea which is similar to the desired one, or one which has some common components or determinants. Thus, bureau is used to mean granfather clock which is relatively easy to understand from the external similarity of both pieces of furniture; an hour for grandfather clock because of the relation of the clock to the hours of the day. ...
Sometimes the figures of speech misuse the principle of pars pro toto, in such a way that its least essential component is selected to represent the total concept. For example, a shoe is called "something to dance in." ...
Two ideas which may be subsumed under one overall concept may be used interchangeably particularly when they are abstract. Thus a patient sayd that he is being "subjected to rape," although the confinement in a mental hospital constitutes a different kind of violation of his person.
To a large extent, inappropriate figures of speech are employed, particularly the word murder which recurs constantly for all forms of torment and in the most varied combinations. In many cases, however, it is obvious that the patients are apt to forget that they are using a figure of speech. Their concept of being tormented is so overwhelming that they can only express it by a word such as murder; in certain situations they actually believe they have been murdered. ...
Where the similarity of concepts is closer, a more intelligible, if daring, imagery appears; for example, "vaccination while being mounted" used by a female, and "to perform holy vaccination" used by a male patient, both to express coitus Another example is "Who has hammered this deep hatred into me?" or "Mr. S. has been promenading in figures of speech" which means that Mr. S. was mentioned during a conversation. The expression, "We shall long have been guests of the crematorium," i.e., dead, is indeed quite highbrow (pp. 150-151).
Sullivan, H.S. (1962). Schizophrenia As A Human Process.
Cf. Sullivan's Schizophrenia As A Human Process, (1962, pp. 73-83) "Case 6" concluding portion on the uncanny connotations of urination is also quoted and interpreted in Conceptions Of Modern Psychiatry (1940, etc. , pp. 144-146), where it serves as an illustration of the "classical schizophrenic spread of meaning":
This patient, having had a disturbingly sudden awareness that he must pass urine, is preoccupied with what the act means. This is no idle philosophizing. Patients who have come to trust one--part of the time--often ask questions like "What does it mean when you rub your nose?", or "What does it mean when people cross the right leg over the left?", or "What does it mean when a person sits down to the right of one?". The excerpt gives at least shadowy indication of what is responsible for the puzzlement as to the meaning of urinating. The patient progressed, through a phase of drowsy oreoccupation from which the demand implied in my presence aroused him, to an obscure statment which might be translated: 'I have a tension which I think should be connected with my heterosexual love object. This need to urinate arises. I do so, and the tension is gone, as if it had been connected with you instead of her.' [and regarding the urination after shooting the 4-ball] 'I was growing tense in this game with what's-his-name and the 4-ball in some way associated itself with Miss B. and I touched it and the tension became overwhelming and I had an orgasm and I felt I'd better separate myself from this disturbing personal environment by renewing mediate contact with my girl ["--a lady who in fact scarcely knew of the patient's existence"].'
Sullivan suggests that the regressive potential of urethral sensations, confusion with sexual arousal, "often take incipiently schizophrenic patients to the medical man." Sullivan's following discussion of schizophrenia suggests that
There are two unrelated syndromes confused under the rubric of dementia praecox, or--as it is often used synonymously--schizophrenia. One syndrome is the congeries of signs, and symptoms pertaining to an organic, degenerative disease usually of insidious development. These patients are finally discovered to be psychotic, although no one can say how long the state has been developing. Their outlook is very poor.... I am content that this syndrome be called dementia praecox. The other syndrome is the one about which I am offereing some data. It is primarily a disorder of living, not of the organic substrate. The person concerned becomes schizophrenic--as one episode in his career among others--for situational reasons and more or less abruptly. He may have had months or years of maladjustive living, of one or another of the sorts I have mentioned (pp. 148-149).
Sullivan and schizophrenic language. "Language of Schizophrenia" (1939, in Kasanin, 1944):
Sullivan describes language as a vehicle for obtaining what one wants and needs in the way of interpersonal security via consunsually validated speech. Schizophrenia speech resembles normal speech under circumstances when the normal person does not need to be alert because security is not at issue.
The schizophrenic has given up any hope of satisfaction and is concerned only with the maintenance of security. He shows, often with painful chagrin in retrospect, the autistic type of speech which is probably our seconf nature, and which we certainly show among our intimates, when we are very tired and safe. I diagnose schizophrenia by certain types of disturbance of speech unaccompanied by chagrin, but I have yet to see a schizoprenic early in his illness who has not been chagrined by hearing himself say certain things to me which he recognized afterwards as incommunicative (p. 13). ... [& the "fantastic auditor" attending to social speech and prodding one toward consensually valid utterances] [I]n the schizophrenic...these mythical observers who watch over the speech of the schizophrenic are as immature and undeveloped as the schizophrenic himself. ... The schizophrenic's critic, his observer of speech, shows the same fugitive integration that is so striking in the personal relationships of schizophrenics. The critic passes, as adequate, expressions which are neologistic, is thereby shoked to altertness, and reviews them with chagrin or fear (pp. 14-15).
Meehl, P.E. Schizotaxia, schizotypy, schizophrenia. American Psychologist, 1962, 17, 827-838.
This was a Presidential Address to the American Psychological Association. The central assumption is that "schizophrenia, while its content is learned, is fundamentally a neurological disease of genetic origin" (p. 416).
Meehl's assumption is that Schizotaxia is the "specific" (necessary) factor.
Schizotypy. Cf. DSM-III's "new" categories of Schizoid (301.20) and Schizotypal (301.22) Personality Disorder (pp. 309-310). The essential feature of Schizoid is "a defect in the capacity to form social relationships, evidenced by the absence of warm, tender feelings for others and indifference to praise, criticism, and the feelings of others" (p. 310). The essential feature of Schizotypal is "a personality disorder in which there are various oddities of thought, perception, speech, and behavior that are not severe enough to meet the criteria for Schizophrenia" (p. 312; cf. Borderline Disorder [301.83], p. 321).
Department of Psychiatry, University of Groningen: Schizophrenia