Schizophrenia is one of several psychotic disorders described in
the DSM. People with psychotic disorders lose contact with reality
and often have delusions or hallucinations. People with schizophrenia have a wide
range of symptoms, which can be classified into positive or negative symptoms.
Positive Symptoms
Positive symptoms involve the presence of altered
behaviors. Examples of positive symptoms include delusions, hallucinations,
disorganized speech, and disorganized behavior.
Delusions are false beliefs that are strongly held
despite contradictory evidence. Hallucinations are sensory or
perceptual experiences that happen without any external stimulus. Hallucinations
can occur in any sensory modality, but auditory hallucinations are most common
in schizophrenia. Disorganized speech can also take many forms. For example, a
person with schizophrenia may produce word salad, which
consists of words and sentences strung together in an incoherent way. Examples
of disorganized behavior include inappropriate gestures or laughter, agitated
pacing, or unpredictable violence.
Negative Symptoms
Negative symptoms involve an absence or reduction of normal
behavior. Negative symptoms include emotional flatness, social withdrawal, spare
or uninflected speech, and lack of motivation.
Subtypes of Schizophrenia
Schizophrenia is classified into four subtypes, depending on the symptoms
present at the time of evaluation:
-
Paranoid
type: Characterized by marked delusions or hallucinations and
relatively normal cognitive and emotional functioning. Delusions are usually
persecutory, grandiose, or both. Persecutory delusions involve
a belief that one is being oppressed, pursued, or harassed in some way.
Grandiose delusions involve the belief that one is very
important or famous. This subtype usually happens later in life than the
other subtypes. Prognosis may also be better for this subtype than for other
subtypes.
-
Disorganized
type: Characterized by disorganized behavior, disorganized
speech, and emotional flatness or inappropriateness.
-
Catatonic
type: Characterized by unnatural movement patterns such
as rigid, unmoving posture or continual, purposeless movements, or by
unnatural speech patterns such as absence of speech or
parroting of other people’s speech.
-
Undifferentiated
type: Diagnosis given to a patient that does not meet criteria
for paranoid, disorganized, or catatonic schizophrenia.
Etiology of Schizophrenia
As with other psychological disorders, researchers have studied the
etiology of schizophrenia from different perspectives.
Biological Factors
Research suggests that genes, neurotransmitters, and brain
abnormalities play a role in the onset of schizophrenia:
