Schizophrenia 101
Some signs of the disturbance must persist for a continuous period of at least 6 months
(Criterion C). Prodromal symptoms often prec ede the active phase,  and residual symp-
toms may follow it, characterized by mild or subthreshold forms of hallucinations or
delusions. Individuals may express a variety of unusual or odd beliefs that are not of de-
lusional proportions (e.g., ideas of reference or  magical thinking); they may have unusual
perceptual experiences (e.g., sensing the pres ence of an unseen person); their speech may
be generally understandable but vague; and their behavior may be unusual but not grossly
disorganized (e.g., mumbling in public). Negative symptoms are common in the pro-
dromal and residual phases and can be seve re. Individuals who had been socially active
may become withdrawn from previous routines . Such behaviors are often the first sign of
a disorder.
Mood symptoms and full mood episodes ar e common in schizophrenia and may be con-
current with active-phase symptomatology. However, as distinct from a psychotic mood dis-
order, a schizophrenia diagnosis requires the presence of delusions or hallucinations in the
absence of mood episodes. In addition, mood ep isodes, taken in total,  should be present for
only a minority of the total duration of th e active and residual periods of the illness.
In addition to the five symptom domain areas identified in the diagnostic criteria, the
assessment of cognition, depression, and mani a symptom domains is vital for making crit-
ically important distinctions between the va rious schizophrenia spectrum and other psy-
chotic disorders.
Associated Features Supporting Diagnosis
Individuals with schizophrenia may display inappropriate affect (e.g., laughing in the ab-
sence of an appropriate stimulus); a dysphoric mood that can take the form of depression,