Schizophrenia Spectrum and Other Psychotic Disorders

Schizophrenia spectrum and other psychotic disorders include

schizophrenia, other psychotic disorders, and schizotypal (personality) disorder. They are defined by abnormalities in one or more of the following five domains: delusions, hallucinations, disorganized thinking

(speech), grossly disorganized or abnormal motor behavior (including catatonia), and negative symptoms.

Key Features That Define the Psychotic Disorders

Delusions

Delusions are fixed beliefs that are not amenable to change in light of conflicting evidence. Their content may include a variety of themes (e.g., persecutory, referential, somatic, religious,

grandiose). Persecutory delusions (i.e., belief that one is going to be harmed, harassed, and so forth by an individual, organization, or other group) are most common. Referential delusions

(i.e., belief that certain gestures, comments, environmental cues, and so forth are directed at oneself) are also common. Grandiose delusions (i.e., when an individual believes that he or she has exceptional abilities, wealth, or fame) and erotomanic delusions (i.e., when an individual believes falsely that another person is in love with him or her) are also seen. Nihilistic delusions involve the conviction that a major catastrophe will occur, and somatic delusions focus on preoccupations regarding health and organ function.

Delusions are deemed bizarre if they are clearly implausible and not understandable to sameculture peers and do not derive from ordinary life experiences. An example of a bizarre delusion is the belief that an outside force has removed his or her internal organs and replaced them with someone else's organs without leaving any wounds or scars. An example of a nonbizarre delusion is the belief that one is under surveillance by the police, despite a lack of convincing evidence. Delusions that express a loss of control over mind or body are generally considered to be bizarre; these include the belief that one's thoughts have been "removed" by some outside force (thought withdrawal), that alien thoughts have been put into one's mind (thought insertion), or that one's body or actions are being acted on or manipulated by some outside force

(delusions of control).

The distinction between a delusion and a strongly held idea is sometimes difficult to determine and depends in part on the degree of conviction with which the belief is held despite clear or reasonable contradictory evidence regarding its veracity. Assessing delusions in individuals from a variety of cultural backgrounds can be difficult. Some religious and supernatural beliefs (e.g., evil eye, causing illness through curses, influence of spirits) may be viewed as bizarre and possibly delusional in some cultural contexts but be generally accepted in others. However, elevated religiosity can be a feature of many presentations of psychosis.

Individuals who have experienced torture, political violence, or discrimination can report fears that may be misjudged as persecutory delusions; these may represent instead intense fears of recurrence or posttraumatic symptoms. A careful evaluation of whether the person's fears are justified given the nature of the trauma can help to differentiate appropriate fears from persecutory delusions.