87Schizophrenia Spectrum and
Other Psychotic Disorders
Schizophrenia spectrum  and other psychotic disorders include schizophrenia,
other psychotic disorders, and schizotypal (per sonality) disorder. They are defined by ab-
normalities in one or more of the following fi ve domains: delusions, hallucinations, disor-
ganized thinking (speech), grossly disorganiz ed or abnormal moto r 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, reli-
gious, grandiose). Persecutory delusions  (i.e., belief that one is going to be harmed, harassed,
and so forth by an individual, organizat ion, or other group) are most common. Referential
delusions  (i.e., belief that certain gestures, comm ents, 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 ma jor 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
same-culture peers and do not derive from or dinary life experiences.  An example of a bi-
zarre delusion is the belief that an outside forc e has removed his or her internal organs and