brain

Schizophrenia (Lam, 2019)

STUDY TITLE: Comparative genetic architectures of schizophrenia in East Asian and European populations

SUMMARY: Discovery of 53 novel schizophrenia-associated genetic loci in East Asian and European populations.

OVERVIEW:  Schizophrenia is a mental disorder that affects how an individual perceives and interacts with reality. It is characterized by hallucinations, delusions, as well as abnormal thinking and behavior that impairs daily function. To discover novel genetic determinants of schizophrenia, this genome-wide association study included genomes of over 58,000 individuals of East Asian ancestry in addition to a cohort of European ancestry. The study identified a total of 208 genetic variants across 178 genetic loci of which 53 were novel. Together the variants identified in this study explain ~ 3% of schizophrenia risk. The study also revealed that the genetic basis of schizophrenia and its biology is shared across populations.

DID YOU KNOW? Symptoms of schizophrenia typically begin to appear during childhood. Daily living support, social skills training, as well as individual and family therapy have been shown to help schizophrenia patients. [SOURCE]

SAMPLE RESULTS: Learn more about the Nebula Research Library.

SCHIZOPHRENIA-ASSOCIATED VARIANTS: rs9257566, rs75970938, rs1716180, rs7596038, rs2159100, rs7476192, rs58120505, rs2949006, rs66691851, rs17592552, rs1198588, rs11210892, rs4666990, rs4702, rs7785663, rs3929747, rs4855019, rs13262595, rs2577831, rs1926026, rs214475, rs10873538, rs11633534, rs6694545, rs217289, rs302321, rs6804239, rs7001340, rs117325001, rs13107325, rs6874127, rs2190864, rs28735056, rs9890128, rs4632296, rs2153960, rs3802924, rs7926389, rs72934570, rs28681284, rs35225048, rs172531, rs7605813, rs17164, rs4132385, rs61937595, rs3814881, rs6633421, rs2057884, rs17194490, rs9607782, rs13230421, rs2514218, rs11685299, rs3732386, rs1792709, rs374528934, rs6995307, rs55661361, rs57346805, rs12031518, rs8188203, rs5757730, rs13376709, rs7733403, rs58146172, rs11663602, rs7499362, rs41356645, rs2333321, rs2801578, rs10861879, rs13142920, rs11587347, rs7067170, rs160593, rs7676765, rs999494, rs2381760, rs148415900, rs2927176, rs6994019, rs2189806, rs9841616, rs13355485, rs72639203, rs12363019, rs117074560, rs6986895, rs13335685, rs77502336, rs71428218, rs76442143, rs6721549, rs17687067, rs9567393, rs758129, rs9342117, rs2319280, rs62152284, rs13164092, rs13261217, rs4793885, rs13284900, rs12328348, rs112222723, rs72986630, rs975025, rs1043009, rs5943630, rs867743, rs6128857, rs9636107, rs6670165, rs2010476, rs2767713, rs10517289, rs147786161, rs1451488, rs111589530, rs942820, rs3088186, rs1075195, rs7127399, rs2293018, rs7673823, rs419677, rs6938026, rs215412, rs72829007, rs79210963, rs4479913, rs4243617, rs946106, rs4365348, rs78895722, rs13019859, rs9420, rs10515678, rs1676062, rs75365967, rs28419375, rs11038391, rs73477270, rs2236989, rs59721702, rs79527984, rs11958187, rs73229090, rs10791099, rs2917568, rs337718, rs12104272, rs1357318, rs62244881, rs61257528, rs6703335, rs1483245, rs59159185, rs13004237, rs4734654, rs783540, rs2957582, rs3849490, rs61847303, rs4766428, rs7811417, rs3810449, rs533123, rs12421382, rs10777342, rs2634447, rs7599488, rs138636117, rs11878180, rs76262184, rs9656169, rs77441740, rs9569820, rs323169, rs12969453, rs112316332, rs117465168, rs5757773, rs200528994, rs793571, rs6797774, rs1191551, rs11615992, rs7271624, rs4697446, rs832190, rs1999512, rs61826793, rs76432012, rs6864084, rs2358740, rs28886334, rs1997529, rs9975024, rs6983764, rs12083902, rs1440849, rs17635239, rs74912003, rs11230827, rs7951609, rs28607014

ADDITIONAL RESOURCES:
Schizophrenia

WEEKLY UPDATE: December 12, 2019

Schizophrenia Information

The term schizophrenia or schizophrenic psychosis refers to mental illnesses or psychotic disorder with similar symptom patterns belonging to the group of psychoses.

In the acute stage of the disease, a schizophrenic person suffer from a variety of characteristic disorders that affect almost all areas of inner experience and behavior. This includes perception, thinking, emotional and emotional life, will formation, psychomotor skills and drive.

Often, voices that are not really present are heard (so-called voice hearing). Additionally, the delusion of being followed, spied on or controlled can occur. Furthermore, the feeling can occur of being controlled by others, e.g. through thought withdrawal or thought inspiration. Persistent hallucinations of any sensory modality are possible.

Social withdrawal, lack of drive, lack of motivation, emotional flattening and joylessness are often observed. Depending on the prevailing symptoms, several subgroups of schizophrenia are distinguished. Medical laypersons often incorrectly associate schizophrenia with the notion of a “split personality”, as the literal translation of the term (schizophrenia = “split soul”) seems to suggest this.

In most of the geographical cultures studied to date, the risk of schizophrenia in the general population is approximately 0.5% to 1%. The risk of developing the disease is the same for men and women, with men statistically being affected at a slightly earlier age. Although schizophrenic disorders have been described since ancient times, no single single cause has been identified. As of 2020, it is therefore assumed that there is an interaction of several triggering factors.

In many cases, the symptoms disappear after the initial phase of the disease. Thereafter, further phases of the disease relapses or psychotic episodes may follow at irregular intervals. In about one third of the patients, all symptoms disappear completely after a certain point. In about another third, recurrences occur repeatedly. In the last third, the course of the disease becomes chronic, leading to a permanent mental disability.

In rare cases, patients with bipolar disorder may experience hallucinations. However, the hallucinations of schizophrenic patients are much more intense and severe.

Symptoms

The symptoms of schizophrenia are traditionally divided into two broad areas: Positive symptoms and negative symptoms. Recently, however, the cognitive symptoms of the disorder have also received increasing attention and are seen as a separate third area.

Contrary to what the term suggests, however, it does not refer to intelligence deficits, but to problems with attention, memory and planning of actions, among other things. The extent to which patients are affected in these areas best predicts how well they will be able to cope with everyday life. Cognitive disorders of this kind are a central symptom complex of schizophrenia. Thinking can become short-stepped, and multilayered relationships can no longer be understood in their complexity. Linguistic expression becomes impoverished.

The severity of the symptoms depends in part on the personality of the person affected. Although the symptoms vary greatly between individuals, the individual patients often retain their individual pattern of symptoms for long periods of time. Health professionals and mental health professionals should be consulted for diagnosis. Once a person is diagnosed with schizophrenia, they can explore treatment options such as prescription of antipsychotic medications or attend support groups. Patients will constantly be monitored for relapses and long term side effects.

The Signs and Symptoms of Schizophrenia
Examples of Positive and Negative Schizophrenia Symptoms, Source

Positive symptoms

Positive symptoms refer to exaggerations of the normal experience and are therefore seen as a kind of “excess” of the healthy state. These include severe misconceptions of the experienced reality such as hallucinations and loss of reality. Schizophrenia with predominantly positive symptoms often begins suddenly, and there are often no outwardly noticeable features before the onset of the condition. The course of the disease is rather favorable.

Characteristic positive symptoms are content-related thinking disorders, ego disorders, sensory delusions and inner restlessness. Typical for the content-related thinking disorders is the formation of a delusion. Acoustic hallucinations often occur. About 84% of people with schizophrenic psychosis perceive thoughts that they think originate from outside. For example, they perceive voices that in rare cases also give orders. This is commonly referred to as “hearing voices”. Frequently affected persons have the impression of being offended by foreign voices. Such an experience can occur while being alone or in the middle of sentences that people around you are saying.

The ego-disturbances include:

  • Thought inspiration: Experiencing one’s own thoughts as being imposed by others
  • Propagation of thoughts: Imagination that others could “listen to” or “read” your own thoughts
  • Thought withdrawal: feeling of loss, that others steal or cut off your thoughts
  • Remote control: Feeling of being controlled by others like a remote-controlled robot.

Negative symptoms

Negative symptoms refer to limitations in normal experience and mental functions that were previously present but have been reduced or completely absent due to the disease. These symptoms therefore represent a deficiency compared to the healthy state.

Example of Negative Symptoms Include:

  • Lack of range of emotion expression, perception, and experience. The impoverishment of the emotions (affects) manifests itself in a reduced ability to “emotionally participate”. The affected persons only react to normally moving events to a limited extent, appearing little affected by both the pleasant and the unpleasant. The normal change between different affective states (joy, curiosity, sadness, anger, pride …) is lost.
  • Alogy Lack of linguistic expressions with delayed, taciturn answers and a little differentiated language. Including disorganized speech.
  • Asociality Lack of sociability in the form of disinterest in dealing with other people, social withdrawal, few friends and few sexual interests (not to be confused with antisocial behavior)
  • Avolition lack of ability to start and maintain goal-oriented behavior
  • Driving disorder Reduced ability and willingness to engage in purposeful activity (lack of drive)
  • Abulie lack of willpower in the form of difficulty in making decisions
  • apathy lack of excitability and insensitivity to external stimuli, which leads to apathy and disinterest
  • Anhedonia lack of ability to feel joy and lust or pleasure
  • “dynamic emptying” Lack of motivation for activities with resulting lack of drive Includes a lack of future planning, up to a lack of prospects.
  • Motor deficits Lack of facial expressions and gestures with reduced movement play. These deficits often make the sufferer appear hostile or out of touch. This distance can be bridged by affection, which is usually gratefully accepted by the patient, even if they cannot show it through facial expressions and gestures. The impoverishment of psychomotor skills makes the affective resonance appear more impaired than it is. So if the patients are not addressed during a solidified state of delusion, they are usually receptive to attention.

Schizophrenia with pronounced negative symptoms often begins insidiously and the course of the disease is rather unfavorable. Negative symptoms can occur months or years before the acute psychotic symptoms. Early symptoms are very often sleep disorders and depressive symptoms. The negative symptoms usually intensify or harden with increasing duration of the illness.

Causes

The general explanation for the cause of schizophrenic psychoses is currently based on a multifactorial interplay of biological (e.g. genetic, infectious, metabolic) and psychosocial (e.g. social environment, psychological stress in the biography) causes. Accordingly, several of these factors in combination can trigger schizophrenia – as shown in the vulnerability stress model. Exceeding a stress threshold is considered the triggering factor that causes the psychosis to break out in a biologically susceptible (vulnerable) person. A misregulation of information processing is considered to be central.

Is Schizophrenia Genetics?

Genes play a role in the risk factor of developing schizophrenia. However, there is no single “schizophrenia gene”. However, a small percentage of schizophrenia patients appear to have a small deletion (microdeletion) in a region of chromosome 22, known as 22q11. As such is is generally considered that a combination of genetic and environmental factors lead to schizophrenia.

The closer a person is to a schizophrenic patient, the more likely he or she is to have his or her own illness. In the case of a schizophrenic parent it is five to ten percent, in the case of sick siblings eight to ten percent. In the case of identical twins 45 percent, and about 21 percent in the case of fraternal twins. If schizophrenia were a purely genetically caused disease, it would have to be 100 percent in the case of identical twins.

Schizophrenia.com - Schizophrenia Genetics and Heredity
Risk of Developing Schizophrenia, Source

However, in the context of the gene-environment interaction, for example, birth complications such as lack of oxygen, infection or stress on the mother, increase the risk of developing schizophrenia. Patients with schizophrenia tend to have immune system defects. Biographical, psychological and social factors can also be significantly responsible for the development of schizophrenia if genetic vulnerability is present.

The Role of Genetic and Environmental Factors in the Development of  Schizophrenia | Psychiatric Times
Genes Involved with the Onset of Schizophrenia, Source

Neurobiology

It is known through imaging techniques that the brain shows multiple variations in anatomy and physiology in the case of schizophrenia. Recent research is looking to clarify the connection between certain deviations and the expected course of the disease.

Diagnosis of schizophrenia is also accompanied by biochemical changes in the brain. It is also known through imaging techniques that in schizophrenia, the signal transmission between nerve cells in the brain deviates from their normal functioning with regard to the neurotransmitter systems that work with dopamine, GABA, or glutamate.

New study finds evidence for reduced brain connections in schizophrenia |  EurekAlert! Science News
Example of Neurological Changes in the Brain of Schizophrenia Patients, Source

Toxic factors

In general, substances that strongly alter the consciousness promote the onset of schizophrenia. However, it is not possible to make sweeping statements since it depends on both the genetic disposition and the individual personality. Psychotropic substances such as alcohol, amphetamines, cocaine and phencyclidine can trigger substance-induced psychoses.

It is also known that nonconsciousness-altering substances such as steroids can also cause a psychosis. Observations of experimentally generated psychoses, such as those induced by hallucinogens, allow the conclusion that experimentally generated psychosis is a useful model for acute schizophrenic psychoses (relapses).

Hormonal factors

There has been evidence for many decades that estrogens have an influence on the risk of the disease and the severity of symptoms. More recently , it has been shown that, as an addition to normal drug treatment, selective estrogen receptor modulators, such as raloxifene, can slightly reduce the symptoms of schizophrenia and can be used for longer periods of time, both in women and men.

Psychosocial factors

Ego developmental deficits or serious neglect in the first years of life can be factors that lead to greater susceptibility to disease, increasing vulnerability.

In a comprehensive follow-up study, it was found that children of mothers who had described their child as “unwanted” in late pregnancy were more than twice as likely to develop schizophrenia during their lifetime as a control group. According to the authors, the results suggested that either psychosocial stress during pregnancy or a particular tendency in the mother’s general behavior was associated with increased risk.

A 2012 meta-analysis confirmed that the risk of developing schizophrenia increased with the size of the home, up to a factor of 2.37 when comparing the most rural and the most urbanized environments. In evaluating this result, the authors emphasized that both specific influences of the urban environment and specific family members or personal factors that influenced the choice of place of residence could be considered as possible causes.

There is also evidence that the incidence of childhood trauma in the biographies of people with schizophrenia is statistically increased.

The National Institute of Mental Health can be referred for more information on Schizophrenia treatment, diagnosis and causes.

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