The delusional form of schizophrenia is manifested in the statements and behavior of the patient, who defends his false beliefs with unquestioned tenacity. The most characteristic for this disease is a staged developing chronic delirium. 
The German psychiatrist K. Konrad singled out several stages in the dynamics of schizophrenic delirium formation. The first signs of its development (trema phase) are characterized by symptoms such as confusion and anxiety of the patient. He learns to live with a new altered consciousness, he is filled with new inexplicable sensations, not always clear, which causes tension and a sense of fear. Depending on the plot of the first delusional thoughts, a feeling of guilt may appear, against which suicidal thoughts arise. Elevated mood is much less common in patients in this phase. 
The next, second stage in the development of delirium formation is (apofenia), delusional "insight". The crystallization of delirium begins - the patient concretizes his delusional ideas, he finds himself in captivity. At the same time, the situation for him becomes more definite, doubts disappear, confusion and tension subside. Patients at this stage often feel like "the center of the universe", the only ones with true knowledge. Delirium at this stage is usually logical and quite believable.
The phase of the disaster or apocalyptic is characterized by incoherent hallucinatory delirium. This stage does not occur at all. It is characterized by a serious disorganization of thinking, speech disorders, the occurrence of irreversible negative symptoms.
Not always the occurrence of delirium occurs in stages. It can manifest itself in the form of an acute paranoid outbreak or grow out of an overvalued idea based on real life facts, from which the patient draws his conclusions that contradict practical experience. Delirium has the character of a belief; the patient does not require evidence of his innocence. He is convinced of it.
In official psychiatry, the initial stage of delirium formation is called paranoid. At this stage, delirium is not yet accompanied by hallucinations and is logically structured. The patient interprets the events and behavior of the people around him quite plausibly. Often at this stage the symptoms of delirium have not yet reached a significant height and are not particularly noticeable. Those around them interpret them as oddities of character. The patient sometimes goes to the doctor, but not to the psychiatrist, but to the therapist, neurologist, cardiologist complaining of a loss of strength, headache or heartache, difficulty falling asleep, unusual sensations in different parts of the body. He may have some eccentricities, obsessions, irritability, poor concentration, forgetfulness amid anxiety or, less often, an overly joyful mood, but at the initial stage of a patient’s complaints, they are usually diagnosed with vegetovascular disorders, neurosis, or manifestations of osteochondrosis. And with certainty, a psychiatrist will still not be able to diagnose schizophrenia in the initial stage with the developing process of delirium formation. For this, long-term monitoring of the patient is necessary.
Psychiatrists also know the so-called Kandinsky symptom, which is characteristic of the initial stage of schizophrenia and is presumably caused by disorders of the vestibular apparatus and the autonomic nervous system. Patients complain of bouts of severe myrrh-like headache, against which they hardly maintain coordination in space, there is a feeling of weightlessness, and the patient just leaves the soil under his feet, he feels “like Armstrong on the moon.”
A brighter debut is acute psychosis. It is manifested by a sudden and rapid increase in symptoms. In addition to the obvious disorganization of thinking, in most cases, the patient can be abnormally excited, aggressive, prone to destructive actions, or, less commonly, overly enthusiastic and obsessed with an idea of often global proportions. He develops psychomotor agitation and requires urgent hospitalization in a psychiatric hospital. The patient is under the supervision of specialists and he is more likely to start treatment in a timely manner.
The gradual development of delirium formation leads to constant not too noticeable changes in the patient's behavior. He is less and less concerned about life realities, family and work problems. He removes himself from them, becoming more and more self-contained. Nevertheless, against the background of general detachment, the patient shows ingenuity and activity, trying to realize his ideas: writes letters to various authorities, tracks down rivals, tries to expose ill-wishers or to realize himself as a reformer. He cannot be convinced of wrongness by any logical arguments and proofs or his energy can be redirected to another, more real direction. 
A typical symptom of schizophrenic delirium is aimless philosophies or schizophasia. The patient cannot be stopped, he speaks incessantly, and moreover coherently, without using parasitic words. However, the meaning in his monologue is simply absent.
The paranoid stage may persist for a long time, but it is schizophrenia, in contrast to schizotypal disorders, that is a progressive disease, and over time, disorganization of the systematic structure of delirium, more often monotemic, and an increase in deficit changes are observed to a greater or lesser extent.
Paranoid delirium is gradually transforming into paranoid - new topics appear, multidirectional, devoid of reality, delirium becomes more and more chaotic. The patient has broken thinking, which is manifested by speech disorders: sudden stops, abrupt change of subject, inconsistency, mentism, abstract statements that make speech noticeably meaningless. The vocabulary is also reduced, it often does not use prepositions and / or conjunctions, does not take initiative in the conversation, answering briefly and not in essence, but hooking on a favorite topic, it cannot stop. Speech is replete with repetitions, not always understood by neologisms, and the loss of grammatical structure. The presence of all these symptoms is not necessary, they appear depending on the depth of the psyche lesion.
Psychiatrists, based on observations of patients, note the following features of delirium with schizophrenia: it practically does not reflect the benign personality traits of the patient, since completely new personality traits appear under the influence of the pathological process (A.Z. Rosenberg), this is confirmed by O.V. Kerbikov calling this phenomenon a delirium of rebirth. Psychiatrists also note a slow systematization of delusional judgments, pretentiousness, full of abstractions and symbolism, a big gap from reality.
In the paranoid stage, pseudo- and true hallucinations are added to the delirium - involuntary perception of objects that are actually absent. In schizophrenics, pseudo-hallucinations occur more often, the patient understands their unreality, but is not able to show a critical attitude towards them. He unquestioningly obeys and believes in sounding voices that he hears with an “inner ear”. Basically, with delusional schizophrenia, patients experience auditory hallucinations, and the most typical are voices giving orders, accusing, threatening, or simply obsessive sounds (howling wind, pouring or dripping water, creaks, whistles, stomping) without verbal registration. Other types of hallucinations (visual, olfactory, tactile) may also be present, but they do not occupy the main place in the clinical picture. After the appearance of hallucinations, the delirium “crystallizes”, becomes more distinct, its content becomes complicated and takes on a fantastic color.
Then the paraphrenic stage of the disease can occur. It is characterized by the so-called “pathological intellectual creativity” (M. I. Rybalsky). The peculiarities of paraphrenic delirium are the inconstancy and variability of the first individual components of the plot, then of certain events, which ends with a change in the whole plot. The patient at this stage feels better, begins to “remember” his past life, it seems to him that the disease is receding. The mood in a patient with paraphrenic syndrome is usually upbeat, speech is emotional, systematized. They are charismatic and can be persuasive, especially in cases where the plot of the delirium is quite real. But in most cases, paraphrenia delirium is distinguished by its fantastic absurd content. The patient often develops megalomania. He feels himself the messiah, capable of changing the history of mankind, appropriating great discoveries for himself, in contact with aliens or otherworldly forces.
Delusional schizophrenia in elderly patients often begins immediately with paraphrenic syndrome. In this case, a depressive type of its course and delusions of "small scope" are characteristic - elderly schizophrenics are mostly convinced that imaginary ill-wishers (relatives or neighbors often play this role) oppress them, do not like them, want to get rid of them, try to deceive and cause damage (poison, injure, deprive housing). Even in the presence of delusions of grandeur, it is pessimistic in nature: it was underestimated, around it ill-wishers "put sticks in the wheels", etc. 
For deep pathological changes in the structure of the psyche in the paranoid or paraphrenic stage, not only hallucinations, but also mental automatisms are characteristic. They are divided into motor ones - the patient claims that he does not move of his own free will, but following orders from the outside; ideational, concerning the thought process (thoughts translate from the outside, replacing them with their own); sensory - external imposition of sensations. According to patients, the most fantastic sources of external influence are foreign intelligence services, aliens, witches, often in the person of an old acquaintance, colleague or neighbor. Influence on the patient can be carried out, according to his ideas, by means of wave radiation, for example, through a radio stream or a transmitter built into an electric bulb. Mental automatisms, coupled with delusions of exposure, are described in psychiatry as Kandinsky-Clerambo syndrome, the most common in the symptom complex of developed schizophrenia.
In the general clinical picture of schizophrenia, along with delusions, various emotional disturbances take place: depressed mood, manic episodes, panic attacks, attacks of apathy or aggression.
True schizophrenia should progress and lead to the appearance of a specific schizophrenic defect, otherwise the disease is diagnosed as a schizotypic personality disorder. The development of negative symptoms can inhibit the correct treatment, a sluggish course of the disease. In general, paranoid delusional schizophrenia is not characterized by such pronounced manifestations as incoherent speech, inadequate associations, impoverishment of emotions, flattening of feelings, catatonic disorders, striking disorganization of behavior. Nevertheless, negative symptoms, although not too pronounced, manifest themselves over a long period of the disease or each of its attacks ends with some losses - a narrowing of the circle of communication, interests, and a decrease in motor activity.