Psychiatric Disorders/Psychotic Disorders
Psychotic disorders include the following disorders: Schizophrenia, Schizoaffective Disorder, Schizophreniform Disorder, Delusional Disorder, Brief Psychotic Disorder, and the Secondary Psychotic Disorders (Psychotic Disorder that are due to medical conditions or to substances). The central feature of these disorders is that they cause psychosis. Psychosis can be thought of as a loss of contact with reality. A person with a psychotic disorder is unable to evaluate properly what is or is not real.
In addition to the primary psychotic disorders, a number of other psychiatric disorders can cause a person to become psychotic. These include the mood disorders, such as psychotic depression, or mania with psychosis.
Thought Disorders 
Psychotic disorders represent the failure of normal thought and, hence, they can be categorized as thought disorders. Thought disorders can be divided into different types. Most commonly, they are divided into disorders of process and disorders of content.
Disorders of Thought Process 
Disorders of thought process involve a disturbance in the way one formulates thought. Thought disorders are inferred from speech, and often referred to as "disorganized speech." Historically, thought disorders have included associative loosening, illogical thinking, over inclusive thinking, and loss of the ability to engage in abstract thinking. Associative loosening includes circumstantial thought and tangential thought.
Other types of formal thought disorder include:
- Perseveration: the patient gets stuck on one idea or one thing and cannot move on from there)
- Clanging: the connections between thoughts may be tenuous, and the patient uses rhyming and punning
- Neologisms: words that patients make up; often a condensation of several words that are unintelligible to another person
- Echolalia: the patient repeats back the words of other people, “parrots” people’s speech
- Thought blocking: stopping mid-thought and being unable to continue with the thought
- Word salad: an incomprehensible mixing of meaningless words and phrases.
- For a larger list of thought disorders, see this article
Disorders of Thought Content 
Disorders of thought content include hallucinations and delusions.
Hallucinations are perceptions without external stimuli. They are most commonly auditory, but may be any type. Auditory hallucinations are often voices, mumbled or distinct. Visual hallucinations can be simple or complex, in or outside the field of vision (ex. "in head") and are usually of normal color rather than black and white. Olfactory and gustatory hallucinations generally occur together as unpleasant tastes and smells. Tactile or haptic hallucinations may include any sensation—for example, an electrical sensation or the feeling of bugs on skin (formication).
Delusions are fixed, false beliefs, not amendable by logic or experience. There are a variety of types. Delusions are most commonly persecutory, but may be somatic, grandiose, religious or nihilistic. No one type of delusion is specific to any particular disorder (such as schizophrenia). Hallucinations and delusions are common across all cultures and backgrounds; however, culture may influence their content. Culture and religion must be considered when evaluating whether an event is a delusion or hallucination. In this context, a good rule of thumb is that if other people endorse it, it may not be a delusion or hallucination.
Lack of Insight 
Truly psychotic persons have a breakdown in the ability to analyze their own thoughts rationally. This may best distinguish psychotic disorders (like schizophrenia) from "normal" misperceptions. Most psychotic patients thus have poor insight into their own illness, which can make compliance with treatment difficult.