20200710 Schizophrenia

Friday, 10 July

#Today I wanna write about one of mental illness in Korean Drama It's Okay, That's Love, schizophrenia.

https://www.dreamstime.com/schizophrenia-vector-illustration-labeled-mental-abnormal-behavior-disorder-understanding-reality-problems-false-beliefs-unclear-image154280988

I took this article from website https://en.m.wikipedia.org/wiki/Schizophrenia

Schizophrenia is a mental illness characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (often hearing voices), delusions (having beliefs not shared by others), and disorganized thinking. Other symptoms include social withdrawal, decreased emotional expression, and lack of motivation. Symptoms typically come on gradually, begin in young adulthood, and in many cases never resolve. There is no objective diagnostic test; diagnosis is based on observed behavior, a history that includes the person's reported experiences, and reports of others familiar with the person. To be diagnosed with schizophrenia, symptoms and functional impairment need to be present for six months, (DSM-5), or one month, (ICD-11). Many people with schizophrenia have other mental disorders that often includes an anxiety disorder such as panic disorder, an obsessive-compulsive disorder, or a subtance use disorder. 

About 0.3% to 0.7% of people are affected by schizophrenia during their lifetime. In 2017, there were an estimated 1.1 million new cases and in 2019 a total of 20 million cases globally. Males are more often affected and on average have an earlier onset. The causes of schizophrenia include genetic and environmental factors. Genetic factors include a variety of common and rare genetic variants. Possible environmental factors include being raised in a city, cannabis use during adolescence, infections, the ages of a person's mother or father, and poor nutrition during pregnancy. 

About half of those diagnosed with schizophrenia will have a significant improvement over the long term with no further relapses, and a small proportion of these will recover completely. The other half will have a lifelong impairment, and severe cases may be repeatedly admitted to hospital. Social problems such as long-term unemployment, poverty, homelessness, exploitation, and victimization are common consequences of schizophrenia. Compared to the general population, people with schizophrenia have a higher suicide rate (about 5% overall) and more physical health problems leading to an average decreased life expectancy of 20 years. In 2015, an estimated 17,000 people worldwide died from behavior related to or caused by schizophrenia.

The mainstay of treatment is an antipsychotic medication, along with counselling, job training, and social rehabilitation. Up to a third of people do not respond to initial antipsychotics, in which case the antipsychotic clozapine may be used. In situations where there is a risk of harm to self or others, a short involuntary hospitalization may be necessary. Long-term hospitalization may be needed for a small number of people with severe schizophrenia. In countries where supportive services are limited or unavailable, long-term hospital stays are more typical.

Schizophrenia is a mental disorder characterized by significant alterations in perception, thoughts, mood, and behavior. Symptoms are described in terms of positive, negative, and cognitive symptoms. The positive symptoms of schizophrenia are the same for any psychosis and are sometimes referred to as psychotic symptoms. These may be present in any of the different psychoses, and are often transient making early diagnosis of schizophrenia problematic. Psychosis noted for the first time in a person who is later diagnosed with schizophrenia is referred to as a first-episode psychosis (FEP). 

Positive symptom are those symptoms that are not normally experienced, but are present in people during a psychotic episode in schizophrenia. They include delusions, hallucinations, and disorganized thoughts and speech, typically regarded as manifestations of psychosis. Hallucinations most commonly involve the sense of hearing as hearing voices but can sometimes involve any of the other senses of taste, sight, smell, and touch. They are also typically related to the content of the delusional theme. Delusions are bizarre or persecutory in nature. Distortions of self-experience such as feeling as if one's thoughts or feelings are not really one's own, to believing that thoughts are being inserted into one's mind, sometimes termed passivity phenomena, are also common. Thought disorders can include thought blocking, and disorganized speech – speech that is not understandable is known as word salad. Positive symptoms generally respond well to medication, and become reduced over the course of the illness, perhaps related to the age-related decline in dopamine activity.

Negative symptoms are deficits of normal emotional responses or of other thought processes. The five recognised domains of negative symptoms are: emotional blunting – showing flat expressions or little emotion; alogia – a poverty of speech; anhedonia – an inability to feel pleasure; asociality – the lack of desire to form relationships, and avolition– a lack of motivation and apathy. Other related symptoms are social withdrawal, self-neglect particularly in hygiene, and self-care, and loss of judgment. Negative symptoms appear to contribute more to poor quality of life, functional impairment, and to the burden on others than do positive symptoms. People with greater negative symptoms often have a history of poor adjustment before the onset of illness. Negative symptoms are less responsive to medication, and are the most difficult to treat. 

Cognitive deficits are the earliest and most constantly found symptoms in schizophrenia. They are often evident long before the onset of illness in the prodromal stage, and may be present in early adolescence, or childhood. They are a core feature but not considered to be core symptoms, as are positive and negative symptoms. However, their presence and degree of dysfunction is taken as a better indicator of functionality than the presentation of core symptoms. Cognitive deficits become worse at first episode psychosis but then return to baseline, and remain fairly stable over the course of the illness.

The deficits in cognition are seen to drive the negative psychosocial outcome in schizophrenia, and are claimed to equate to a possible reduction in IQ from the norm of 100 to 70–85. Cognitive deficits may be of neurocognition (nonsocial) or of social cognition. Neurocognition is the ability to receive and remember information, and includes verbal fluency, memory, reasoning, problem solving, speed ofprocessing, and auditory and visual perception. Verbal memory and attention are seen to be the most affected. Verbal memory impairment is associated with a decreased level of semantic processing (relating meaning to words). Another memory impairment is that of episodic memory. An impairment in visual perception that is consistently found in schizophrenia is that of visual backward masking. Visual processing impairments include an inability to perceive complex visual illusions. Social cognition is concerned with the mental operations needed to interpret, and understand the self and others in the social world. This is also an associated impairment, and facial emotion perception is often found to be difficult. Facial perception is critical for ordinary social interaction. Cognitive impairments do not usually respond to antipsychotics, and there are a number of interventions that are used to try to improve them.

Onset typically occurs between the late teens and early 30s, with the peak incidence occurring in males in the early to mid twenties, and in females in the late twenties. Onset before the age of 17 is known as early-onset, and before the age of 13, as can sometimes occur is known as childhood schizophrenia or very early-onset. A later stage of onset can occur between the ages of 40 and 60, known as late-onset schizophrenia. A later onset over the age of 60 which may be difficult to differentiate as schizophrenia, is known as very-late-onset schizophrenia-like psychosis. Late onset has shown that a higher rate of females are affected; they have less severe symptoms, and need lower doses of antipsychotics. There has been a dramatic increase in the numbers of older adults with schizophrenia. An estimated 70% of those with schizophrenia have cognitive deficits, and these are most pronounced in early onset, and late-onset illness.

Onset may happen suddenly, or may occur after the slow and gradual development of a number of signs and symptoms in a period known as the prodromal stage. Up to 75% of those with schizophrenia go through a prodromal stage. The negative and cognitive symptoms in the prodrome can precede FEP by many months, and up to five years. The period from FEP and treatment is known as the duration of untreated psychosis (DUP) which is seen to be a factor in functional outcome. The prodromal stage is the high-risk stage for the development of psychosis. Since the progression to first episode psychosis, is not inevitable an alternative term is often preferred of at risk mental state. Recognition and early intervention at the prodromal stage would minimize the disruption to educational and social development associated with schizophrenia, and has been the focus of many studies. It is suggested that the use of anti-inflammatory compounds such as D-serine may prevent the transition to schizophrenia. Cognitive symptoms are not secondary to positive symptoms, or to the side effects of antipsychotics.

Cognitive impairments in the prodromal stage become worse after first episode psychosis (after which they return to baseline and then remain fairly stable), making early intervention to prevent such transition of prime importance. Early treatment with cognitive behavioral therapies are the gold standard. Neurological soft signs of clumsiness and loss of fine motor movement are often found in schizophrenia, and these resolve with effective treatment of FEP.

Genetic, environmental, and vulnerability factors are involved in the development of schizophrenia. The interactions of these risk factors are complex, as numerous and diverse insults from conception to adulthood can be involved. A genetic predisposition on its own, without interacting environmental factors, will not give rise to the development of schizophrenia. Schizophrenia is described as a neurodevelopmental disorder that lacks a precise boundary in its definition.

Estimates of the heritability of schizophrenia are between 70% and 80%, which implies that 70% to 80% of the individual differences in risk to schizophrenia is associated with genetics. These estimates vary because of the difficulty in separating genetic and environmental influences, and their accuracy has been queried. The greatest risk factor for developing schizophrenia is having a first-degree relative with the disease (risk is 6.5%); more than 40% of identical twins of those with schizophrenia are also affected. If one parent is affected the risk is about 13% and if both are affected the risk is nearly 50%. However, DSM-5 points out that most people with schizophrenia have no family history of psychosis. Results of candidate gene studies of schizophrenia have generally failed to find consistent associations, and the genetic loci identified by genome-wide association studies as associated with schizophrenia explain only a small fraction of the variation in the disease.

Many genes are known to be involved in schizophrenia, each with small effect and unknown transmission and expression. The summation of these effect sizes into a polygenic risk score can explain at least 7% of the variability in liability for schizophrenia. Around 5% of cases of schizophrenia are understood to be at least partially attributable to rare copy-number variations (CNVs); these structural variations are associated with known genomic disorders involving deletions at 22q11.2 (DiGeorge syndrome), duplications at 16p11.2. 16p11.2 duplication (most frequently found) and deletions at 15q11.2 (Burnside-Butler syndrome). Some of these CNVs increase the risk of developing schizophrenia by as much as 20-fold, and are frequently comorbid with autism and intellectual disabilities.

The genes CRHR1 and CRHBP have been shown to be associated with a severity of suicidal behavior. These genes code for stress response proteins needed in the control of the HPA axis, and their interaction can affect this axis. Response to stress can cause lasting changes in the function of the HPA axis possibly disrupting the negative feedback mechanism, homeostasis, and the regulation of emotion leading to altered behaviors.

The question of how schizophrenia could be primarily genetically influenced, given that people with schizophrenia have lower fertility rates, is a paradox. It is expected that genetic variants that increase the risk of schizophrenia would be selected against due to their negative effects on reproductive fitness. A number of potential explanations have been proposed, including that alleles associated with schizophrenia risk confers a fitness advantage in unaffected individuals. While some evidence has not supported this idea, others propose that a large number of alleles each contributing a small amount can persist.

Environmental factors, each associated with a slight risk of developing schizophrenia in later life include oxygen deprivation, infection, prenatal maternal stress, and malnutrition in the mother during fetal development. A risk is also associated with maternal obesity, in increasing oxidative stress, and dysregulating the dopamine and serotonin pathways. Both maternal stress and infection have been demonstrated to alter fetal neurodevelopment through an increase of pro-inflammatory cytokines. There is a slighter risk associated with being born in the winter or spring possibly due to vitamin D deficiency or prenatal viral infection. Other infections during pregnancy or around the time of birth that have been linked to an increased risk include infections by Toxoplasma gondii and chlamydia. The increased risk is about five to eight percent. Viral infections of the brain during childhood are also linked to a risk of schizophrenia during adulthood.

Adverse Childhood Experiences (ACEs), severe forms of which are classed as childhood trauma, range from being bullied or abused, to the death of a parent. Many adverse childhood experiences can cause toxic stress and increase the risk of psychosis. Schizophrenia was the last diagnosis to benefit from the link made between ACEs and adult mental health outcomes.

Living in an urban enviroment during childhood or as an adult has consistently been found to increase the risk of schizophrenia by a factor of two, even after taking into account drug use, ethnic group, and size of social group. A possible link between the urban environment and pollution has been suggested to be the cause of the elevated risk of schizophrenia.

Other risk factors of importance include social isolation, immigration related to social adversity and racial discrimination, family dysfunction, unemployment, and poor housing conditions. Having a father older than 40 years, or parents younger than 20 years are also associated with schizophrenia. 

About half of those with schizophrenia use recreational drugs, including cannabis, nicotine, and alcohol excessively. Use of stimulants such as amphetamine and cocaine can lead to a temporary stimulant psychosis, which presents very similarly to schizophrenia. Rarely, alcohol use can also result in a similar alcohol-related psychosis. Drugs may also be used as coping mechanisms by people who have schizophrenia, to deal with depression, anxiety, boredom, and loneliness. The use of cannabis and tobacco are not associated with the development of cognitive deficits, and sometimes a reverse relationship is found where their use improves these symptoms. However, substance abuse is associated with an increased risk of suicide, and a poor response to treatment.

Cannabis-use may be a contributory factor in the development of schizophrenia, potentially increasing the risk of the disease in those who are already at risk. The increased risk may require the presence of certain genes within an individual. Its use is associated with doubling the rate. The use of more potent strains of cannabis having a high level of its active ingredient tetrahydrocannabinol (THC), increases the risk further. One of these strains is well known as skunk.

The mechanisms of schizophrenia are unknown, and a number of models have been put forward to explain the link between altered brain function and schizophrenia. One of the most common is the dopamine model, which attributes psychosis to the mind's faulty interpretation of the misfiring of dopaminergic neurons. This has been directly related to the symptoms of delusions and hallucinations. Abnormal dopamine signaling has been implicated in schizophrenia based on the usefulness of medications that affect the dopamine receptor and the observation that dopamine levels are increased during acute psychosis. A decrease in D1 receptors in the dorsolateral prefrontal cortex may also be responsible for deficits in working memory. 

Another hypothesis is the glutamate model that links alterations between glutamatergic neurotransmission and neural oscillations that affect connections between the thalamus and the cortex. Studies have shown that a reduced expression of a glutamate receptor - NMDA receptor, and glutamate blocking drugs such as phencycludine and ketamine can mimic the symptoms and cognitive problems associated with schizophrenia. Post-mortem studies consistently find that a subset of these neurons fail to express GAD67 (GAD1), in addition to abnormalities in brain morphometry. The subsets of interneurons that are abnormal in schizophrenia are responsible for the synchronizing of neural ensembles needed during working memory tasks. These give the neural oscillations produced as gamma waves that have a frequency of between 30 and 80 hertz. Both working memory tasks and gamma waves are impaired in schizophrenia, which may reflect abnormal interneuron functionality.

There are often impairments in cognition, social skills, and motor skills before the onset of schizophrenia, which suggests a neurodevelopmental model. Such frameworks have hypothesized links between these biological abnormalities and symptoms. Furthermore, problems before birth such as maternal infection, maternal malnutrition and complications during pregnancy all increase risk for schizophrenia. Schizophrenia usually emerges 18-25, an age period that overlaps with certain stages of neurodevelopment that are implicated in schizophrenia.

Deficits in executive functions, such as planning, inhibition, and working memory, are pervasive in schizophrenia. Although these functions are dissociable, their dysfunction in schizophrenia may reflect an underlying deficit in the ability to represent goal related information in working memory, and to utilize this to direct cognition and behavior. These impairments have been linked to a number of neuroimaging and neuropathological abnormalities. For example, functional neuroimaging studies report evidence of reduced neural processing efficiency, whereby the dorsolateral prefrontal cortex is activated to a greater degree to achieve a certain level of performance relative to controls on working memory tasks. These abnormalities may be linked to the consistent post-mortem finding of reduced neuropil, evidenced by increased pyramidal cell density and reduced dendritic spine density. These cellular and functional abnormalities may also be reflected in structural neuroimaging studies that find reduced grey matter volume in association with deficits in working memory tasks.

Positive symptoms have been linked to reduced cortical thickness in the superior temporal gyrus. Severity of negative symptoms has been linked to reduced thickness in the left medial orbitofrontal cirtex. Anhedonia, traditionally defined as a reduced capacity to experience pleasure, is frequently reported in schizophrenia. However, a large body of evidence suggests that hedonic responses are intact in schizophrenia, and that what is reported to be anhedonia is a reflection of dysfunction in other processes related to reward. Overall, a failure of reward prediction is thought to lead to impairment in the generation of cognition and behavior required to obtain rewards, despite normal hedonic responses.

It has been hypothesized that in some people, development of schizophrenia is related to intrstinal tract dysfunction such as seen with non-celiac gluten sensitivity or abnormalities in the gut microbiota. A subgroup of persons with schizophrenia present an immune response to gluten differently from that found in people with celiac, with elevated levels of certain serum biomarkers of gluten sensitivity such as anti-gliadin IgG or anti-gliadin IgA antibodies.

Another theory links abnormal brain lateralization to the development of being left-handed which is significantly more common in those with schizophrenia. This abnormal development of hemispheric assymetry is noted in schizophrenia. Studies have concluded that the link is a true and verifiable effect that may reflect a genetic link between lateralization and schizophrenia.

Bayesian models of brain functioning have been utilized to link abnormalities in cellular functioning to symptoms. Both hallucinations and delusions have been suggested to reflect improper encoding of prior expectations, thereby causing expectation to excessively influence sensory perception and the formation of beliefs. In approved models of circuits that mediate predictive coding, reduced NMDA receptor activation, could in theory result in the positive symptoms of delusions and hallucinations.

There is no objective test or biomarker to confirm diagnosis. Psychoses can occur in several conditions and are often transient making early diagnosis of schizophrenia difficult. Psychosis noted for the first time in a person that is later diagnosed with schizophrenia is referred to as a first-episode psychosis (FEP).

Schizophrenia is diagnosed based on criteria in either the Diagnostic and Statistical Manual of Mental Disorders (DSM) published by the American Psychiatric Association, or the International Statistical Classification of Diseases and Related Health Problems (ICD) published by the World Health Organization. These criteria use the self-reported experiences of the person and reported abnormalities in behavior, followed by a psychiatric assessment. The mental status examination is an important part of the assessment. An established tool for assessing the severity of positive and negative symptoms is the Positive and Negative Syndrome Scale (PANSS). This has been seen to have shortcomings relating to negative symptoms, and other scales – the Clinical Assessment Interview for Negative Symptoms (CAINS), and the Brief Negative Symptoms Scale (BNSS) have been introduced. DSM-5, the fifth edition was published in 2013, and gives a Scale to Assess the Severity of Symptom Dimensions outlining eight dimensions of symptoms.

DSM-5 states that to be diagnosed with schizophrenia, two diagnostic criteria have to be met over the period of one month, with a significant impact on social or occupational functioning for at least six months. One of the symptoms needs to be either delusions, hallucinations, or disorganized speech. A second symptom could be one of the negative symptoms, or severely disorganized or catatonic behaviour. A different diagnosis of schizophreniform disorder can be made before the six months needed for the diagnosis of schizophrenia.

In Australia the guideline for diagnosis is for six months or more with symptoms severe enough to affect ordinary functioning. In the UK diagnosis is based on having the symptoms for most of the time for one month, with symptoms that significantly affect the ability to work, study, or to carry on ordinary daily living, and with other similar conditions ruled out.

The ICD criteria are typically used in European countries; the DSM criteria are used predominantly in the United States and Canada, and are prevailing in research studies. In practice, agreement between the two systems is high. The current proposal for the ICD-11criteria for schizophrenia recommends adding self-disorder as a symptom.

A major unresolved difference between the two diagnostic systems is that of the requirement in DSM of an impaired functional outcome. WHO for ICD argues that not all people with schizophrenia have functional deficits and so these are not specific for the diagnosis.

Both manuals have adopted the chapter heading of Schizophrenia spectrum and other psychotic disorders; ICD modifying this as Schizophrenia spectrum and other primary psychotic disorders. The definition of schizophrenia remains essentially the same as that specified by the 2000 text revised DSM-IV (DSM-IV-TR). However, with the publication of DSM-5, the APA removed all sub-classifications of schizophrenia. ICD-11 has also removed subtypes. The removed subtype from both, of catatonic has been relisted in ICD-11 as a psychomotor disturbance that may be present in schizophrenia.

Another major change was to remove the importance previously given to Schneider's first-rank symptoms. DSM-5 still uses the listing of schizophreniform disirder but ICD-11 no longer includes it. DSM-5 also recommends that a better distinction be made between a current condition of schizophrenia and its historical progress, to achieve a clearer overall characterization.

A dimensional assessment has been included in DSM-5 covering eight dimensions of symptoms to be rated (using the Scale to Assess the Severity of Symptom Dimensions) – these include the five diagnostic criteria plus cognitive impairments, mania, and depression. This can add relevant information for the individual in regard to treatment, prognosis, and functional outcome; it also enables the response to treatment to be more accurately described.

Two of the negative symptoms – avolition and diminished emotional expression, have been given more prominence in both manuals.

Many people with schizophrenia have one or more other disorders that often includes an anxiety disorder such as panic disorder, an obsessive-compulsive disorder, or a substance use disorder. These are separate disorders that need separate treatments. Sleep disorders are commonly found with schizophrenia, and are early signs of illness and also of relapse. Sleep disorders are linked with positive symptoms that include disorganized thinking and can adversely affect neocortical plasticity and cognition. The consolidation of memories is disrupted in sleep disorders. They are associated with severity of illness, a poor prognosis, and poor quality of life. Sleep onset and maintenance insomnia is a common symptom, regardless of whether treatment has been received or not. There is also a clozapine-induced somnolence. A related condition is antipsychotic-induced restless legs syndrome. Genetic variations have been found associated with these conditions involving the circadian rhythm, dopamine and histamine metabolism, and signal transduction.

Psychotic symptoms lasting less than a month may be diagnosed as brief psychotic disorder, and various conditions may be classed as psychotic disorder not otherwise specified; schizoaffective disorder is diagnosed if symptoms of mood disorder are substantially present alongside psychotic symptoms. If the psychotic symptoms are the direct physiological result of a general medical condition or a substance, then the diagnosis is one of a psychosis secondary to that condition. Schizophrenia is not diagnosed if symptoms of pervasive developmental disorder are present unless prominent delusions or hallucinations are also present.

Psychotic symptoms may be present in several other conditions, and mental disorders, including bipolar disorder, borderline personality disorder, subtance intoxication, substance-induced psychosis, and a number of drug withdrawal syndromes. Non-bizarre delusions  are also present in delusional disorder, and social withdrawal in social anxiety disorder, avoidant personality disorder, and schizotypal personality disorder. Schizotypal personality disorder has symptoms that are similar but less severe than those of schizophrenia. Schizophrenia occurs along with obsessive-compulsive disorder (OCD) considerably more often than could be explained by chance, although it can be difficult to distinguish obsessions that occur in OCD from the delusions of schizophrenia.

A more general medical and neurological examination may be needed to rule out medical illnesses which may rarely produce psychotic schizophrenia-like symptoms, such as metabolic disturbance, systemic infection, syphilis, HIV-associated neurocognitive disorder, epilepsy, limbic encephalitis, metabolic disturbance, and brain lesions. Stroke, multiple sclerosis, hyperthyroidism, hypothyroidism, and dementias such as Alzheimer's disease, Huntington's disease, frontotemporal dementia, and the Lewy body dementias may also be associated with schizophrenia-like psychotic symptoms. It may be necessary to rule out a delirium, which can be distinguished by visual hallucinations, acute onset and fluctuating level of consciousness, and indicates an underlying medical illness. Investigations are not generally repeated for relapse unless there is a specific medical indication or possible adverse effects from antipsychotic medication. In children hallucinations must be separated from typical childhood fantasies.

Prevention of schizophrenia is difficult as there are no reliable markers for the later development of the disorder. There is tentative though inconclusive evidence for the effectiveness of early intervention to prevent schizophrenia in the prodrome phase. There is some evidence that early intervention in those with first-episode psychosis may improve short-term outcomes, but there is little benefit from these measures after five years. Cognitive behavioral therapy may reduce the risk of psychosis in those at high risk after a year and is recommended in this group, by the National Institute for Health and Care Excellence (NICE). Another preventive measure is to avoid drugs that have been associated with development of the disorder, including cannabis, cocaine, and amphetamines.

Antipsychotics are prescribed following a first-episode psychosis, and following remission a preventive maintenace use is continued to avoid relapse. However, it is recognised that some people do recover following a single episode and that long-term use of antipsychotics will not be needed but there is no way of identifying this group.

The history of schizophrenia is complex and does not lend itself easily to a linear narrative. Accounts of a schizophrenia-like syndrome are rare in records before the 19th century. The earliest cases detailed were reported in 1797, and 1809. Dementia praecox, meaning premature dementia was used by German psychiatrist Heinrich Schüle in 1886, and then in 1891 by Arnold Pick in a case report of hebephrenia. In 1893 Emil Kraepelin used the term in making a distinction, known as the Kraepelinian dichotomy, between the two psychoses – dementia praecox, and manic depression (now called bipolar disorder). Kraepelin believed that dementia praecox was probably caused by a systemic disease that affected many organs and nerves, affecting the brain after puberty in a final decisive cascade. It was thought to be an early form of dementia, a degenerative disease. When it became evident that the disorder was not degenerative it was renamed schizophrenia by Eugen Bleuler in 1908.

The word schizophrenia translates roughly as "splitting of the mind" and is Modern Latin from the Greek roots schizein (σχίζειν, "to split") and phrēn, (φρεν, "mind")^[247] Its use was intended to describe the separation of function between personality, thinking, memory, and perception. 

The term schizophrenia used to be associated with split personality by the general population but that usage went into decline when split personality became known as a separate disorder, first as multiple identity disorder, and later as dissociative identity disorder. In 2002 in Japan the name was changed to integration disorder, and in 2012 in South Korea, the name was changed to attunement disorder to reduce the stigma, both with good results.

In the early 20th century, the psychiatrist Kurt Schneider listed the psychotic symptoms of schizophrenia into two groups of hallucinations, and delusions. The hallucinations were listed as specific to auditory, and the delusional included thought disorders. These were seen as the symptoms of first-rank importance and were termed first-rank symptoms. Whilst these were also sometimes seen to be relevant to the psychosis in manic-depression, they were highly suggestive of schizophrenia and typically referred to as first-rank symptoms of schizophrenia. The most common first-rank symptom was found to belong to thought disorders. In 2013 the first-rank symptoms were excluded from the DSM-5 criteria. First-rank symptoms are seen to be of limited use in detecting schizophrenia but may be of help in differential diagnosis.

The earliest attempts to treat schizophrenia were psychosurgical, involving either the removal of brain tissue from different regions or the severing of pathways. These were notably frontal lobotomies and cingulotomies which were carried out from the 1930s. In the 1930s a number of shock therapies were introduced which induced seizures (convulsions) or comas. Insulin shock therapy involved the injecting of large doses of insulin in order to induce comas, which in turn produced hypoglycemia and convulsions. The use of electricity to induce seizures was developed, and in use as electroconvulsive therapy (ECT) by 1938. Stereotactic surgeries were developed in the 1940s. Treatment was revolutionized in the mid-1950s with the development and introduction of the first typical antipsychotic, chlorpromazine. In the 1970s the first atypical antipsychotic clozapine, was introduced followed by the introduction of others.

In the early 1970s in the US, the diagnostic model used for schizophrenia was broad and clinically-based using DSM II. It had been noted that schizophrenia was diagnosed far more in the US than in Europe which had been using the ICD-9 criteria. The US model was criticised for failing to demarcate clearly those people with a mental illness, and those without. In 1980 DSM III was published and showed a shift in focus from the clinically-based biopsychosocial model to a reason-based medical model. DSM IV showed an increased focus to an evidence-based medical model. DSM-5 was published in 2013 and introduced changes to DSM IV.

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