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Back to Psychiatry Diseases
Schizophrenia
Schizophrenia is a psychiatric diagnosis denoting a persistent, often
chronic, mental illness variously affecting behaviour, thinking, and
emotion. The term schizophrenia comes from the Greek words (schizo,
split or divide) and (phrenos, mind) and is best translated
"shattered mind".
Introduction
Schizophrenia is most commonly characterised by both 'positive symptoms'
(those additional to normal experience and behaviour) and negative
symptoms (the lack or decline in normal experience or behaviour).
Positive symptoms are grouped under the umbrella term psychosis and
typically include delusions, hallucinations, and thought disorder.
Negative symptoms may include inappropriate or lack of emotion, poverty
of speech, and lack of motivation. Additionally, neurocognitive deficits
may be present. These take the form of reduction or impairment in basic
psychological functions such as memory, attention, problem solving, and
social cognition. The onset is typically in late adolescence and early
adulthood, with males tending to show symptoms earlier than females.
Psychiatrist Emil Kraepelin was first to make the distinction between
what he called dementia praecox and other forms of madness. This
classification was later renamed 'schizophrenia' by psychiatrist Eugene
Bleuler as it became clear Kraepelin's name was not an adequate
description of the condition.
The diagnostic approach to schizophrenia has been opposed, most notably
by the anti-psychiatry movement, who argue that classifying specific
thoughts and behaviours as illness allows social control of people that
society finds undesirable but who have committed no crime.
More recently, it has been argued that schizophrenia is just one end of
a spectrum of experience and behaviour, and everybody in society may
have some such experiences in their life. This is known as the
'continuum model of psychosis' or the 'dimensional approach' and is most
notably argued for by psychologist Richard Bentall and psychiatrist Jim
van Os.
Although no definite causes of schizophrenia have been identified, most
researchers and clinicians currently believe that schizophrenia is
primarily a disorder of the brain. It is thought that schizophrenia may
result from a mixture of genetic disposition (genetic studies using
various techniques have shown relatives of people with schizophrenia are
more likely to show signs of schizophrenia themselves) and environmental
stress (research suggests that stressful life events may precede a
schizophrenic episode).
It is also thought that processes in early neurodevelopment are
important, particularly those that occur during pregnancy. In adult
life, particular importance has been placed upon the function (or
malfunction) of dopamine in the mesolimbic pathway in the brain. This
theory, known as the dopamine hypothesis of schizophrenia largely
resulted from the accidental finding that a drug group which blocks
dopamine function, known as the phenothiazines, reduced psychotic
symptoms. These drugs have now been developed further and antipsychotic
medication is commonly used as a first line treatment. However, this
theory is now thought to be overly simplistic as a complete explanation.
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History
Accounts that may relate to symptoms of schizophrenia date back as far
as 2000 BC in Book of Hearts, a part of the ancient Ebers papyrus.
However, a recent study1 into the ancient Greek and Roman literature
showed that whilst the general population probably had an awareness of
psychotic disorders, there was no condition that would meet the modern
diagnostic criteria for schizophrenia in these societies.
This nonspecific concept of madness has been around for many thousands
of years and schizophrenia was only classified as a distinct mental
disorder by Kraepelin in 1887. He was the first to make a distinction in
the psychotic disorders between what he called dementia praecox (a term
first used by psychiatrist Benedict A. Morel) and manic depression.
Kraepelin believed that dementia praecox was primarily a disease of the
brain2, and particularly a form of dementia. Kraepelin named the
disorder 'dementia praecox' (early dementia) to distinguish it from
other forms of dementia (such as Alzheimer's disease) which typically
occur late in life. He used this term because his studies focused on
young adults with dementia.
The term schizophrenia is derived from the Greek words 'schizo' (split)
and 'phrene' (mind) and was coined by Eugene Bleuler to refer to the
lack of interaction between thought processes and perception. He was
also the first to describe the symptoms as "positive" or "negative."22
Bleuler changed the name to schizophrenia as it was obvious that
Krapelin's name was misleading. The word "praecox" implied precocious or
early onset, hence premature dementia, as opposed to senile dementia
from old age. Bleuler realised the illness was not a dementia (it did
not always lead to mental deterioration) and could sometimes occur late
as well as early in life and was therefore misnamed.
With the name 'schizophrenia' Bleuler intended the name to capture the
separation of function between personality, thinking, memory, and
perception, however it is commonly misunderstood to mean that affected
persons have a 'split personality' (something akin to the character in
Robert Louis Stevenson's The Strange Case of Dr. Jekyll and Mr. Hyde).
Although it is commonly confused with multiple personality disorder,
schizophrenia has nothing to do with the manifestation of distinct
multiple personalities within a person. The confusion perhaps arises in
part due to the meaning of Blueler's term 'schizophrenia'.
Interestingly, the first known misuse of this term to mean 'split
personality' (in the Jekyll and Hyde sense) was in an article by the
poet T. S. Eliot in 19333.
Incidence and prevalence
Schizophrenia is typically diagnosed in late adolescence or early
adulthood. It is found approximately equally in men and women, though
the onset tends to be later in women, who also tend to have a better
course and outcome.
The lifetime prevalence of schizophrenia is commonly given at 1%,
however a recent review of studies from around the world estimated it to
be 0.55%14. The same study also found that prevalence may vary greatly
from country to country, despite the received wisdom that schizophrenia
occurs at the same rate throughout the world. It is worth noting
however, that this may be in part due to differences in the way
schizophrenia is diagnosed. The incidence of schizophrenia was given as
a range of between 7.5 and 16.3 cases per 100,000 of the population.
Schizophrenia is also a major cause of disability. In a recent
14-country study15, active psychosis was ranked the third most disabling
condition after quadriplegia and dementia and before paraplegia and
blindness.
Cause
While the reliability of the schizophrenia 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), there is evidence to suggest that genetic
vulnerability modified by environmental stressors can act in combination
to cause schizophrenia.
A recent review listed seven genes as likely to be involved in the
inheritance of schizophrenia or the risk of developing schizophrenia26.
Evidence comes from research (such as linkage studies) suggesting
multiple chromosomal regions are transmitted to people who are later
diagnosed as having schizophrenia. Some family association studies have
demonstrated a relationship to a gene known as COMT that is involved in
encoding the dopamine catabolic enzyme catechol-O-methyl transferase27.
This is particularly interesting because of the known link between
dopamine function, psychosis, and schizophrenia.
While highly heritable (close to 70%), schizophrenia is a disorder of
complex inheritance (analogous to diabetes or high blood pressure).
Thus, several genes interact to generate risk for schizophrenia. Genetic
evidence for the role of the environment comes from the observation that
identical twins do not universally develop schizophrenia. A recent
review of the genetic evidence have suggested a 28% chance of one
identical twin developing schizophrenia if the other already has it7.
There is also considerable evidence indicating that stress may trigger
episodes of schizophrenia. For example, emotionally turbulent families8
and stressful life events9 have been shown to be risk factors for
relapses or triggers for episodes of schizophrenia. Other factors such
as poverty and discrimination may also be involved. This may explain why
minority communities have much higher rates of schizophrenia than when
members of the same ethnic groups are resident in their home country.
One particularly stable and replicable finding has been the association
between living in an urban environment and risk of developing
schizophrenia, even after factors such as drug use, ethnic group and
size of social group have been controlled for29. A recent study of 4.4
million men and women in Sweden found a 68-77% increased risk of
psychosis for people living in the most urbanised environments, a
significant proportion of which is likely to be accounted for by
schizophrenia30.
In addition to the risk factors listed above, researchers have curiously
found that those suffering from schizophrenia are much more likely to
have been born during the Winter months, particularly February and
March. Researchers studying manic-depressive disorder have also found
that this phenomenon applies to their patients as well.
Although no definite causes of schizophrenia have been identified, most
researchers and clinicians currently believe that schizophrenia is
primarily a disorder of the brain.
It is also thought that processes in early neurodevelopment are
important, particularly during pregnancy. For example, women who were
pregnant during the Dutch famine of 1944, where many people were close
to starvation, had a higher chance of having a child who would later
develop schizophrenia10. Similarly, studies of Finnish mothers who were
pregnant when they found out that their husbands had been killed during
the Winter War of 1939 - 1940 have shown that their children were much
more likely to develop schizophrenia when compared with mothers who were
found out about their husbands' death before or after pregnancy11,
suggesting that even psychological trauma in the mother may have an
effect.
In adult life, particular importance has been placed upon the function
(or malfunction) of dopamine in the mesolimbic pathway in the brain.
This theory, known as the dopamine hypothesis of schizophrenia largely
resulted from the accidental finding that a drug group which blocks
dopamine function, known as the phenothiazines, reduced psychotic
symptoms. These drugs have now been developed further and antipsychotic
medication is commonly used as a first line treatment.
However, this theory is now thought to be overly simplistic as a
complete explanation. Partly as newer antipsychotic medication (called
atypical antipsychotic medication) is equally effective as older
medication, but also affects serotonin function and may have slightly
less of a dopamine blocking effect. Psychiatrist David Healy has also
argued that pharmaceutical companies have promoted certain
oversimplified biological theories of mental illness to promote their
own sales of biological treatments12.
Much recent research has focused on differences in function in certain
brain areas in people diagnosed with schizophrenia. Studies using
neuropsychological tests and brain scanning technologies such as fMRI
and PET have shown that differences seem to most commonly occur in the
frontal lobes, hippocampus, and temporal lobes13. These differences are
heavily linked to the neurocognitive deficits which often occur with
schizophrenia, particularly in areas of memory, attention, problem
solving, and social cognition.
Diagnosis and presentation (signs and symptoms)
Like many mental illnesses, the diagnosis of schizophrenia is based upon
the behaviour of the person being assessed. There is a list of
diagnostic criteria which must be met for a person to be so diagnosed.
These depend on both the presence and duration of certain signs and
symptoms.
The most commonly-used criteria for diagnosing schizophrenia are from
the American Psychiatric Association's Diagnostic and Statistical Manual
of Mental Disorders (DSM) and the World Health Organisation's
International Statistical Classification of Diseases and Related Health
Problems (ICD). The most recent versions are ICD-10 (http://www.who.int/whosis/icd10/)
and DSM-IV-TR (http://www.psych.org/research/dor/dsm/index.cfm).
Below is an abbreviated version of the diagnostic criteria from the
DSM-IV-TR, the full version is available here (http://www.behavenet.com/capsules/disorders/schiz.htm).
To be diagnosed as having schizophrenia, a person must display:
A) Characteristic symptoms: Two or more of the following, each present
for a significant portion of time during a one-month period (or less, if
successfully treated)
delusions
- hallucinations
- disorganized speech (e.g., frequent derailment or incoherence). See
thought disorder.
- grossly disorganized or catatonic behavior
- negative symptoms, i.e., affective flattening (lack or decline in
emotional response), alogia (lack or decline in speech), or avolition
(lack or decline in motivation).
Note: Only one Criterion A symptom is required if delusions are bizarre
or hallucinations consist of hearing voices.
B) 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.
C) 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 successfully treated) that meet Criterion A.
Historically, schizophrenia in the West was classified into simple,
catatonic, hebephrenic, and paranoid. The DSM now contains five
sub-classifications of schizophrenia. These are
- catatonic type (where marked absences or peculiarities of movement are
present),
- disorganised type (where thought disorder and flat or inappropriate
affect are present together),
- paranoid type (where delusions and hallucinations are present but
thought disorder, disorganised behaviour, and affective flattening is
absent),
- residual type (where positive symptoms are present at a low intensity
only) and
- undifferentiated type (psychotic symptoms are present but the criteria
for paranoid, disorganized, or catatonic types has not been met).
Symptoms may also be described as 'positive symptoms' (those additional
to normal experience and behaviour) and negative symptoms (the lack or
decline in normal experience or behaviour). 'Positive symptoms' describe
psychosis and typically include delusions, hallucinations and thought
disorder. 'Negative symptoms' describe inappropriate or nonpresent
emotion, poverty of speech, and lack of motivation.
It is worth noting that many of the positive or psychotic symptoms may
occur in a variety of disorders and not only in schizophrenia. The
psychiatrist Kurt Schneider tried to list the particular forms of
psychotic symptoms which he thought were particularly useful in
distinguishing between schizophrenia and other disorders which could
produce psychosis. These are called first rank symptoms or Schneiderian
first rank symptoms and include delusions of being controlled by an
external force, the belief that thoughts are being inserted or withdrawn
from your conscious mind, the belief that your thoughts are being
broadcast to other people and hearing hallucinated voices which comment
on your thoughts or actions, or may have a conversation with other
hallucinated voices. It now seems that 'first rank symptoms' are not a
reliable method of diagnosing schizophrenia4, however the term might
still be used descriptively by mental health professionals.
Diagnostic issues and controversies
It has been argued that the diagnostic approach to schizophrenia is
flawed, as it relies on an assumption of a clear dividing line between
what is considered to be mental illness (fulfilling the diagnostic
criteria) and mental health (not fulfilling the criteria). Recently it
has been argued, notably by psychiatrist Jim van Os and psychologist
Richard Bentall (in his book Madness Explained), that this makes little
sense, as studies have shown that psychotic symptoms are present in many
people who never become 'ill' in the sense of feeling distressed,
becoming disabled in some way or needing medical assistance6.
Of particular concern is that the decision as to whether a symptom is
present is a subjective decision by the person making the diagnosis or
relies on an incoherent definition (for example, see the entries on
delusions and thought disorder for a discussion of this issue). More
recently, it has been argued that psychotic symptoms are not a good
basis for making a diagnosis of schizophrenia as "psychosis is the
'fever' of mental illness - a serious but nonspecific indicator".5
Proponents have argued for a new approach that would use the presence of
specific neurocognitive deficits to make a diagnosis. These often
accompany schizophrenia and take the form of a reduction or impairment
in basic psychological functions such as memory, attention, and problem
solving. It is these sorts of difficulties, rather than the psychotic
symptoms (which can in many cases by controlled by antipsychotic
medication), which seem to be the cause of most disability in
schizophrenia. However, this argument is relatively new and it is
unlikely that the method of diagnosing schizophrenia will change
radically in the near future.
The diagnostic approach to schizophrenia has also been opposed by the
anti-psychiatry movement, who argue that classifying specific thoughts
and behaviours as an illness allows social control of people that
society finds undesirable but who have committed no crime. They argue
that this is a way of unjustly classifying a social problem as a medical
one to allow the forcible detention and treatment of people displaying
these behaviours, which is something which can be done under mental
health legislation in most western countries.
An example of this can be seen in the former Soviet Union, where an
additional sub-classification of sluggishly progressing schizophrenia
was created. Particularly in the RSFSR (Russian Soviet Federated
Socialist Republic) this diagnosis was used for the purpose of silencing
political dissidents or forcing them to recant their ideas by the use of
forcible confinement and treatment. In 2000 similar concerns about the
abuse of psychiatry to unjustly silence and detain members of the Falun
Gong movement by the Chinese government led the American Psychiatric
Association's Committee on the Abuse of Psychiatry and Psychiatrists to
pass a resolution to urge the World Psychiatric Association to
investigate the situation in China.
Western psychiatric medicine tends to favour a definition of symptoms
that depends on form rather than content (an innovation first argued for
by psychiatrists Karl Jaspers and Kurt Schneider). Therefore, you should
be able to believe anything, however unusual or socially unacceptable,
without being diagnosed delusional, unless your belief is judged to be
held in a particular way. In principle this would stop people being
forcibly detained or treated simply for what they believe. However, in
practice the distinction between form and content is not easy, or
sometimes possible, to make (see delusion). This had led to accusations
by anti-psychiatry, surrealist and mental health system survivor groups
that psychiatric abuses exist to some extent in the West as well.
Treatment
The first line treatment for schizophrenia is usually the use of
antipsychotic medication. The newer atypical antipsychotic medication
(such as olanzapine, risperidone and clozapine) is preferred over older
typical antipsychotic medication (such as chlorpromazine and
haloperidol), as the atypicals have different side effect profiles,
including less frequent development of extrapyramidal side-effects.
However, it is still unclear whether newer drugs reduce the chances of
developing the rare but potentially life-threatening neuroleptic
malignant syndrome.
Atypical antipsychotics have been claimed to have additional beneficial
effects on negative as well as positive symptoms. However, the newer
drugs are much more costly as they are still within patent, whereas the
older drugs are available in inexpensive generic forms. Aripiprazole a
drug from a new class of antipsychotic drugs (variously named 'dopamine
system stabilisers' or 'partial dopamine agonists') has recently been
developed and early research suggests that it may be a safe and
effective treatment for schizophrenia16.
Hospitalisation may occur with severe episodes. This can be voluntary or
(if mental health legislation allows it) involuntary (called civil or
involuntary commitment). Mental health legislation may also allow a
person to be treated against their will. However, in many countries such
legislation does not exist, or does not have the power to enforce
involuntary hospitalisation or treatment.
Psychotherapy or other forms of talk therapy may be offered, with
cognitive behavioural therapy being the most frequently used. This may
focus on the direct reduction of the symptoms, or on related aspects,
such as issues of self-esteem, social functioning, and insight. There
have been some promising results with cognitive behavioural therapy, but
the balance of current evidence is inconclusive17.
Other support services may also be available such as drop-in centres,
visits from members of a 'community mental health team' and patient-led
support groups.
In many non-Western societies, schizophrenia may be treated with more
informal, community-led methods. A particularly sobering thought for
Western psychiatry is that outcome for people diagnosed as schizophrenic
in non-Western countries may be actually be much better18 than for
people in the West. The reasons for this are still far from clear,
although cross-cultural studies are being conducted to find out why.
This issue was recently addressed in a highly critical opinion piece
(full article here (http://www.usatoday.com/usatonline/20020304/3909657s.htm))
in the American newspaper USA Today, which noted that the rate of
recovery is much lower in the United States and other developed nations
than in third world countries. Quote:
Most Americans are unaware that the World Health Organization (WHO) has
repeatedly found that long-term schizophrenia outcomes are much worse in
the USA and other developed countries than in poor ones such as India
and Nigeria, where relatively few patients are on anti-psychotic
medications. In undeveloped countries, nearly two-thirds of
schizophrenia patients are doing fairly well five years after initial
diagnosis; about 40% have basically recovered. But in the USA and other
developed countries, most patients become chronically ill. The outcome
differences are so marked that WHO concluded that living in a developed
country is a strong predictor that a patient never will fully recover.
Prognosis
Prognosis for any particular individual affected by schizophrenia is
particularly hard to judge as treatment and access to treatment is
continually changing as new methods become available and medical
recommendations change.
However, retrospective studies have shown that about a third of people
make a full recovery, about a third show improvement but not a full
recovery, and a third remain ill19.
There is an extremely high suicide rate associated with schizophrenia. A
recent study showed that 30% of patients diagnosed with this condition
had attempted suicide at least once during their lifetime20. Another
study suggested that 10% of persons with schizophrenia die by suicide21.
Schizophrenia and drug use
Schizophrenia can sometimes be triggered by heavy use of hallucinogenic
drugs, especially LSD; but it appears that one has to have a
predisposition towards developing schizophrenia for this to occur. There
is also some evidence suggesting that people suffering schizophrenia but
responding to treatment can have an episode as a result of use of LSD.
Ironically, it was mainly for experimental treatment of schizophrenia
that LSD administration was legal briefly before the popularity of that
drug led to its criminalization. Methamphetamine, ketamine and PCP also
mimic the symptoms of schizophrenia, and can trigger ongoing symptoms of
schizophrenia in those who are vulnerable.
There is now increasing evidence that cannabis use can be a contributing
trigger to developing schizophrenia. The most recent studies suggest
that cannabis is neither a sufficient nor necessary factor in developing
schizophrenia, but that cannabis may significantly increase the risk of
developing schizophrenia and may be, among others, a significant causal
factor31.
It has been noted that the majority of people with schizophrenia
(estimated between between 75% and 90%) smoke tobacco. However, people
diagnosed with schizophrenia have a much lower than average chance of
getting and dying from lung cancer. While the reason for this is
unknown, it may be because of a genetic resistance to the cancer, a
side-effect of drugs being taken, or a statistical effect of increased
likelihood of dying from causes other than lung cancer22. It is argued
that the increased level of smoking in schizophrenia may be due to a
desire to self-medicate with nicotine. A recent study of over 50,000
Swedish conscripts found that there was a small but significant
protective effect of smoking cigarettes on the risk of developing
schizophrenia later in life.28 Whilst the authors of the study stressed
that the risks of smoking far outweigh these minor benefits, this study
provides further evidence for the 'self-medication' theory of smoking in
schizophrenia and may gives clues as to how schizophrenia might develop
at the molecular level.
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