is a psychiatric diagnosis that
describes a mental
disorder characterized by abnormalities in the perception or expression of
reality. Distortions in perception may affect all five senses, including sight, hearing, taste, smell and touch,
but most commonly manifest as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking with
significant social or occupational dysfunction. Onset of symptoms typically
occurs in young adulthood, with
approximately 0.4–0.6% of the
population affected. Diagnosis is based on the patient's self-reported
experiences and observed behavior. No laboratory test for schizophrenia
currently exists.
Studies suggest that genetics,
early environment, neurobiology, psychological and social processes are important
contributory factors; some recreational and prescription drugs appear to cause
or worsen symptoms. Current psychiatric research is focused on the role of
neurobiology, but no single organic cause has been found. Due to the many
possible combinations of symptoms, there is debate about whether the diagnosis
represents a single disorder or a number of discrete syndromes. For this reason,
Eugen Bleuler termed the
disease the schizophrenias (plural) when he coined the name. Despite its
etymology, schizophrenia is not the same as dissociative identity disorder,
previously known as multiple personality disorder or split personality, with
which it has been erroneously confused.
Increased dopamine activity in
the mesolimbic
pathway of the brain is consistently found in schizophrenic individuals. The
mainstay of treatment is antipsychotic medication; this type of drug
primarily works by suppressing dopamine activity. Dosages of antipsychotics are
generally lower than in the early decades of their use. Psychotherapy, and vocational and social
rehabilitation are also important. In more serious cases—where there is risk to
self and others—involuntary hospitalization may be necessary, although hospital
stays are less frequent and for shorter periods than they were in previous
times.
The disorder is thought to mainly affect cognition, but it also usually contributes to chronic
problems with behavior and emotion. People with schizophrenia are likely to have
additional (comorbid)
conditions, including major depression and anxiety
disorders; the
lifetime occurrence of substance abuse is around 40%. Social problems,
such as long-term unemployment, poverty and homelessness, are common.
Furthermore, the average life expectancy of people with the disorder is
10 to 12 years less than those without, due to increased physical health
problems and a higher suicide rate A person diagnosed with schizophrenia may demonstrate auditory hallucinations, delusions, and disorganized and unusual
thinking and speech; this may range from loss of train of thought and
subject flow, with sentences only loosely connected in meaning, to incoherence,
known as word salad, in
severe cases. Social isolation commonly occurs for a variety of reasons.
Impairment in social
cognition is associated with schizophrenia, as are symptoms of paranoia from
delusions and hallucinations, and the negative symptoms of avolition (apathy or lack of motivation). In one
uncommon subtype, the person may be largely mute, remain motionless in bizarre
postures, or exhibit purposeless agitation; these are signs of catatonia. No one sign is diagnostic
of schizophrenia, and all can occur in other medical and psychiatric
conditions. The
current classification of psychoses holds that symptoms need to have been
present for at least one month in a period of at least six months of disturbed
functioning. A schizophrenia-like psychosis of shorter duration is termed a schizophreniform disorder.[4]
Late adolescence and early adulthood are peak years for the onset of
schizophrenia. In 40% of men and 23% of women diagnosed with schizophrenia, the
condition arose before the age of 19. These are
critical periods in a young adult's social and vocational development, and they
can be severely disrupted. To minimize the effect of schizophrenia, much work
has recently been done to identify and treat the prodromal (pre-onset) phase of the illness, which has
been detected up to 30 months before the onset of symptoms, but may be present
longer. Those who go on to develop schizophrenia may experience the non-specific
symptoms of social withdrawal, irritability and dysphoria in the prodromal period,
and transient or self-limiting psychotic symptoms in the prodromal phase before
psychosis becomes apparent. The most widely used standardized criteria for diagnosing schizophrenia come
from the American Psychiatric
Association's Diagnostic
and Statistical Manual of Mental Disorders, version DSM-IV-TR, and the
World Health Organization's International Statistical
Classification of Diseases and Related Health Problems, the ICD-10. The
latter criteria are typically used in European countries, while the DSM criteria
are used in the United States and the rest of the world, as well as prevailing
in research studies. The ICD-10 criteria put more emphasis on Schneiderian first-rank symptoms,
although, in practice, agreement between the two systems is high.
According to the revised fourth edition of the Diagnostic and Statistical
Manual of Mental Disorders (DSM-IV-TR), to be diagnosed with schizophrenia,
three diagnostic criteria must be met:
- Characteristic symptoms: Two or more of the following, each present
for much of the time during a one-month period (or less, if symptoms remitted
with treatment).
- If the delusions are judged to be bizarre, or hallucinations consist of
hearing one voice participating in a running commentary of the patient's actions
or of hearing two or more voices conversing with each other, only that symptom
is required above. The speech disorganization criterion is only met if it is
severe enough to substantially impair communication.
- Social/occupational dysfunction: For a significant portion of the
time since the onset of the disturbance, one or more major areas of functioning
such as work, interpersonal relations, or self-care, are markedly below the
level achieved prior to the onset.
- Duration: Continuous signs of the disturbance persist for at least
six months. This six-month period must include at least one month of symptoms
(or less, if symptoms remitted with treatment).
Schizophrenia cannot be diagnosed if symptoms of mood disorder or pervasive developmental
disorder are present, or the symptoms are the direct result of a general
medical condition or a substance, such as abuse of a drug or medication.
The DSM-IV-TR
contains five sub-classifications of schizophrenia.
The ICD-10 defines two
additional subtypes.
While the reliability of the diagnosis introduces difficulties in measuring
the relative effect of genes and environment (for example, symptoms overlap to
some extent with severe bipolar disorder or major
depression), evidence suggests that genetic and environmental
factors can act in combination to result in schizophrenia. Evidence
suggests that the diagnosis of schizophrenia has a significant heritable
component but that onset is significantly influenced by environmental factors or
stressors The idea of
an inherent vulnerability (or diathesis) in some people, which can be
unmasked by biological, psychological or environmental stressors, is known as
the stress-diathesis model. The idea that biological, psychological and social factors are all important is
known as the "biopsychosocial" model.
Estimates of the heritability of schizophrenia tend to vary owing
to the difficulty of separating the effects of genetics and the environment
although twin studies have suggested a high level of
heritability. It has been suggested that schizophrenia is a condition of complex inheritance,
with several genes
possibly interacting to generate risk for schizophrenia or the separate
components that can co-occur leading to a diagnosis. These genes
appear to be non-specific, in that they may raise the risk of developing other
psychiatric disorders such as bipolar disorder. Although metaanalyses of genetic linkage studies have produced
conflicting findings,
larger-scale, thus more sensitive genome-wide association studies
have produced stronger evidence for association to specific risk loci such as
the zinc finger protein 804A. Schizophrenia has
also been associated with rare deletions or duplications of tiny DNA sequences
(known as copy number variants) disproportionately
occurring within genes involved in neuronal signaling and brain development.
There is little doubt about the existence of a fecundity deficit in
schizophrenia. Affected individuals have fewer children than the population as a
whole. This reduction is of the order of 70% in males and 30% in females. The
central genetic paradox of schizophrenia is why, if the disease is associated
with a biological disadvantage, is this variation not selected out? To balance
such a significant disadvantage, a substantial and universal advantage must
exist. Thus far, all theories of a putative advantage have been disproved or
remain unsubstantiated.
Causal factors are thought to initially come together in early neurodevelopment to increase the risk of later
developing schizophrenia. One curious finding is that people diagnosed with
schizophrenia are more likely to have been born in winter or spring, (at least
in the northern hemisphere).
There is now
evidence that prenatal exposure to infections increases the risk for
developing schizophrenia later in life, providing additional evidence for a link
between in utero developmental pathology and risk of developing the
condition
Living in an urban
environment has been consistently found to be a risk factor for
schizophrenia. Social disadvantage has been found to be a risk factor, including poverty
and migration
related to social adversity, racial discrimination, family dysfunction,
unemployment or poor housing conditions. Childhood experiences of abuse or trauma have also been implicated as risk
factors for a diagnosis of schizophrenia later in life. Parenting is not held responsible for schizophrenia but unsupportive
dysfunctional relationships may contribute to an increased risk.
Although about half of all patients with schizophrenia abuse drugs or
alcohol, a clear causal connection between drug use and schizophrenia has been
difficult to prove. The two most often used explanations for this are "substance
use causes schizophrenia" and "substance use is a consequence of schizophrenia",
and they both may be correct. A 2007 meta-analysis estimated that
cannabis use is statistically associated with a dose-dependent increase in risk of
development of psychotic disorders, including schizophrenia. There is little evidence to suggest that other drugs including alcohol cause
schizophrenia, or that psychotic individuals choose specific drugs to
self-medicate; there is some support for the theory that they use drugs to cope
with unpleasant states such as depression, anxiety, boredom and loneliness.
However, regarding psychosis
itself, it is well understood that methamphetamine and cocaine use can result in methamphetamine or cocaine
induced psychosis which presents very similar symptomatology and may persist
even when users remain abstinent.
An approach broadly known as the anti-psychiatry movement, most active in the
1960s, opposes the orthodox medical view of schizophrenia as an illness. Psychiatrist Thomas Szasz
argued that psychiatric patients are not ill, but rather individuals with
unconventional thoughts and behavior that make society uncomfortable. He
argues that society unjustly seeks to control them by classifying their behavior
as an illness and forcibly treating them as a method of social control. According
to this view, "schizophrenia" does not actually exist but is merely a form of social
construction, created by society's concept of what constitutes normality and
abnormality. Szasz has never considered himself to be "anti-psychiatry" in the
sense of being against psychiatric treatment, but simply believes that treatment
should be conducted between consenting adults, rather than imposed upon anyone
against his or her will.
Psychiatrists R. D.
Laing, Silvano
Arieti, Theodore
Lidz and others have argued that the symptoms of what is called mental
illness are comprehensible reactions to impossible demands that society and
particularly family life places on some sensitive individuals. Laing, Arieti and
Lidz were notable in valuing the content of psychotic experience as worthy of interpretation,
rather than considering it simply as a secondary and essentially meaningless
marker of underlying psychological or neurological distress. Laing described
eleven case studies of people diagnosed with schizophrenia and argued that the
content of their actions and statements was meaningful and logical in the
context of their family and life situations. In 1956, Palo
Alto, Gregory
Bateson and his colleagues Paul Watzlawick, Donald
Jackson, and Jay Haley articulated a
theory of schizophrenia, related to Laing's work, as stemming from double bind situations where a
person receives different or contradictory messages. Madness was therefore an
expression of this distress and should be valued as a cathartic and transformative experience. In the books
Schizophrenia and the Family and The Origin and Treatment of
Schizophrenic Disorders Lidz and his colleagues explain their belief that
parental behaviour can result in mental illness in children. Arieti's Interpretation of
Schizophrenia won the 1975 scientific National Book Award in the United
States.
The concept of schizophrenia as a result of civilization has been developed
further by psychologist Julian Jaynes in his 1976 book The
Origin of Consciousness in the Breakdown of the Bicameral Mind; he
proposed that until the beginning of historic times, schizophrenia or a similar
condition was the normal state of human consciousness. This
would take the form of a "bicameral mind" where a normal state of low
affect, suitable for routine activities, would be interrupted in moments of
crisis by "mysterious voices" giving instructions, which early people
characterized as interventions from the gods. Researchers into shamanism have speculated
that in some cultures schizophrenia or related conditions may predispose an
individual to becoming a shaman; the
experience of having access to multiple realities is not uncommon in
schizophrenia, and is a core experience in many shamanic traditions. Equally,
the shaman may have the skill to bring on and direct some of the altered states of consciousness
psychiatrists label as illness. Psychohistorians, on the other hand, accept the
psychiatric diagnoses. However, unlike the current medical model
of mental disorders they may argue that poor parenting
in tribal societies causes the shaman's schizoid personalities. Commentators such
as Paul Kurtz and others have
endorsed the idea that major religious figures experienced psychosis, heard
voices and displayed delusions of grandeur.
Psychiatrist Tim Crow has
argued that schizophrenia may be the evolutionary price we pay for a left brain
hemisphere specialization for language. Since
psychosis is associated with greater levels of right brain hemisphere activation
and a reduction in the usual left brain hemisphere dominance, our language
abilities may have evolved at the cost of causing schizophrenia when this system
breaks down. Other approaches have linked schizophrenia to psychological dissociation
or states of awareness and identity understood from phenomenological and other
perspectives.
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