Schizophrenia (Lam, 2019) – Is schizophrenia genetic?

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Nebula Genomics DNA Report for Schizophrenia

Is schizophrenia genetic? We created a DNA report based on a study that attempted to answer this question. Below you can see a SAMPLE DNA report. To get your personalized DNA report, purchase our Whole Genome Sequencing!

A sample report on schizophrenia from Nebula Genomics
A sample report on schizophrenia genetic variants from Nebula Genomics

Additional Information

What is Schizophrenia? (Part 1 of Is schizophrenia genetic?)

The term schizophrenia refers to a serious mental illness or psychotic disorder with symptoms similar to that of psychoses, where the patient interprets reality in an abnormal way. 

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

Often, patients hear voices that are not really present. Additionally, the delusion of being followed, spied on, or controlled can occur. Persistent hallucinations of any sensory modality are also possible.

A person with schizophrenia will often display characteristics that appear as social withdrawal, lack of drive, lack of motivation, emotional flattening, and joylessness. Depending on the prevailing symptoms, several subgroups of schizophrenia are distinguished. It’s important to note that schizophrenia and split personality disorder are not the same. The former does not associate with multiple personalities as the latter does. Schizophrenia is also distinct from bipolar disorder, a different mental illness that causes extreme mood shifts. 

In many cases, the symptoms disappear after the initial phase of the disease. Thereafter, further phases of the disease relapses or episodes of psychosis 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.

Epidemiology (Part 2 of Is schizophrenia genetic?)

As of 2019, schizophrenia is known to affect 20 million people worldwide. It is not as common as other mental health conditions. People who develop the condition are 2 – 3 times more likely to die early than the general population due to physical illnesses, such as cardiovascular, metabolic and infectious diseases.

The risk of developing the disease is the same for men and women, although usually schizophrenia affects men at a slightly earlier age. Men may exhibit symptoms in the early to mid-20s while a woman’s symptoms typically begin in the late 20s. It’s uncommon for children to be diagnosed with schizophrenia and rare for those older than age 45.

A map of relevant prevalence of schizophrenia around the world
The greatest impacts of schizophrenia are in Oceania, the Middle East, and East Asia. Lokal_Profil. Attribution-Share Alike 2.5 Generic.

Symptoms (Part 3 of Is schizophrenia genetic?)

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

According to Mayo Clinic, signs and symptoms may vary among individuals, but usually include delusions, hallucinations or disorganized speech, and reflect an impaired ability to function. 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. 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. 

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.

There are various positive symptoms of schizophrenia including:

  1. Delusions. False beliefs that are not based in reality. For example, you think that you’re being harmed or harassed; another person is in love with you; or a major catastrophe is about to occur. Delusions are one of the most common symptoms in people with schizophrenia.
  2. Hallucinations. Seeing or hearing things that don’t exist. While hallucinations can be in any of the five senses, hearing voices is the most common hallucination.
  3. Disorganized thinking (speech). Disorganized thinking is observed when speech becomes disorganized. Effective communication can be impaired, and answers to questions may be partially or completely unrelated. 
  4. Extremely disorganized or abnormal motor behavior. These symptoms vary from childlike silliness to unpredictable agitation. It’s hard for individuals to do tasks. Behavior can include resistance to instructions, inappropriate or bizarre posture, a complete lack of response, or useless and excessive movement.

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.

For example, the person may neglect personal hygiene or appear to lack emotion (doesn’t make eye contact, doesn’t change facial expressions or speaks in a monotone). The person may lose interest in everyday activities, socially withdraw or lack the ability to experience pleasure.

Schizophrenia with pronounced negative symptoms often begins gradually and the course of the disease can be 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 (Part 4 of Is schizophrenia genetic?)

No single single cause for schizophrenia has been identified. As of 2020, it is assumed that there is an interaction of several triggering factors

The general explanation for the cause of schizophrenia 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. Exceeding a stress threshold is considered the triggering factor that causes the psychosis to break out in a biologically susceptible (vulnerable) person. 

Risk factors
Schizophrenia is thought to be caused by both genetic and environmental factors. Shawncho. Attribution-Share Alike 3.0 Unported.

Is schizophrenia genetic?

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

Having a family member with or family history of schizophrenia is known to increase the risk of developing the disorder. In the case of a schizophrenic parent, it is five to ten percent likely that a child will develop it. In the case of siblings, it is eight to ten percent. In the case of identical twins 45 percent, and about 21 percent in the case of fraternal twins.

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.

Non-genetic factors

Neurobiology

Imaging techniques demonstrate that the brain shows multiple variations in anatomy and physiology in cases 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. For example, 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.

Schizophrenia also appears to develop when there is an imbalance of a neurotransmitter called dopamine, and possibly also serotonin, in the brain.

Differences in brain scans between controls and persons with schizophrenia
Changes in brain chemistry are observed in patients with schizophrenia. Pixy.org.

Toxic factors

In general, use of substances that strongly alter consciousness lead to a higher risk of schizophrenia. However, it also 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 non consciousness-altering substances such as steroids can cause a psychosis. 

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. Trauma during birth, malnutrition before birth, viral infections, and additional trauma may also contribute to disease development. 

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.

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

Diagnosis (Part 5 of Is schizophrenia genetic?)

To diagnose schizophrenia, a doctor will use the criteria from the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). 

According to the criteria, a person must have at least two of the following symptoms for a month:

  • delusions
  • hallucinations
  • disorganized speech
  • grossly disorganized or catatonic behavior
  • negative symptoms, such as lack of speech, emotional flatness, or lack of motivation

They must also experience considerable impairment in their ability to function in school or at work, to interact with others, or to carry out self-care tasks, and they must have symptoms that persist for 6 months or more.

It can be hard to tell the difference between schizophrenia and a similar condition called schizoaffective disorder. The latter brings on schizophrenia-like symptoms but is characterized by a detachment from reality rather than altered reality. 

Treatment (Part 6 of Is schizophrenia genetic?)

Schizophrenia is a lifelong condition but various medications can help control symptoms, improve quality of life, and help patients avoid hospitalization. According to Medical News Today, treatment options include:

  • Antipsychotic drugs 
    • risperidone (Risperdal)
    • olanzapine (Zyprexa)
    • quetiapine (Seroquel)
    • ziprasidone (Geodon)
    • clozapine (Clozaril)
    • haloperidol (Haldol)
  • Counseling
  • Coordinated special care

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

If you liked this article, you should check out our other posts in the Nebula Research Library!