What Is Schizophrenia?


Schizophrenia is a disorder characterised by delusions, hallucinations, disorganised speech, disorganised behaviour, and emotional bluntness that can lead to impaired social functioning.

It has a poor prognosis for some patients and a chronic course that causes considerable distress to patients and their families, but recent advances in treatment, including pharmacological therapies, have made early diagnosis and treatment a priority.

The term “schizophrenia” may be unfamiliar to some, as it was renamed schizophrenia in 2011. The name was changed to eliminate stigma, as schizophrenia was seen as socially alienating and rejected.

The word “schizophrenia” comes from the dictionary definition of tuning, which means to pick the strings of a stringed instrument, and refers to the chaotic state of a person with schizophrenia, much like a stringed instrument that is out of tune.


There is currently no clear cause of schizophrenia, but it is generally accepted that it is a biological disorder caused by an abnormality in the brain.

However, as with other chronic diseases such as hypertension and diabetes, there is no single explanation for the cause of schizophrenia; it is thought to be a combination of biological and genetic causes, as well as psychological causes such as stress.

In terms of biological causes, the most popular hypothesis is that schizophrenia is caused by too much of a neurotransmitter called dopamine in the brain, although it is not yet clear why this substance is abnormal in the brain.

In addition, various abnormalities have been observed in the frontal lobe, limbic system, and basal ganglia, suggesting that abnormalities in these areas of the brain may be involved in the etiology of schizophrenia.

In the case of genetic causes, it is known that schizophrenia, like many other chronic diseases, is hereditary to some extent, but the causative gene for schizophrenia has not been found.

It is also known that even in identical twins with exactly the same genes, if one twin has schizophrenia, there is a 50% chance that the other twin will develop schizophrenia, and since it is possible to develop schizophrenia even without having a relative with schizophrenia, it is difficult to consider it as a hereditary disease, and it is thought that genetic causes are not all.

In addition to this, psychological causes such as stress are also known to be involved, and there is a theory that people with a predisposition to a vulnerable brain may develop schizophrenia when they are subjected to environmental stress or trauma.

However, schizophrenia is known to occur in all walks of life and all over the world, and it is not known to be caused by parenting or childhood problems.

Schizophrenia is not directly related to psychological trauma or childhood upbringing, and people may experience temporary psychotic symptoms when they are overwhelmed by a traumatic event, but over time, their behaviour returns to normal, and they are not diagnosed as schizophrenic and do not progress to schizophrenia.


Although schizophrenia is described as a single disorder, it is actually a group of disorders with similar symptoms but different causes. People with schizophrenia have a variety of clinical presentations, treatment responses, and disease courses.

There are no specific symptoms that are unique to schizophrenia. Therefore, a diagnosis of schizophrenia should not be made on the basis of a mental status examination alone, but should be differentiated from a range of internal medical conditions and other psychiatric disorders.

The most common symptoms of schizophrenia are delusions and hallucinations.

Delusions are an impairment in thinking, in which a person is convinced that something is true, even though it is not, given the person’s educational and cultural background. Delusions can range from paranoia and megalomania to somatic delusions.

Hallucinations are perceptions in the absence of external stimuli to the sensory organs as if they were present, and are qualitatively similar to real perceptions. In schizophrenia, auditory hallucinations are most common, most often of human voices, but also other sounds and music.

The person may also exhibit disorganised language and behaviour, with strange words and actions, and catatonic behaviour, in which movement and communication are severely slowed.

In schizophrenia, voice symptoms tend to become more pronounced over time, including decreased emotional expression, decreased motivation, and decreased interpersonal relationships. Negative symptoms are the absence of normal mental functions.


A diagnosis of schizophrenia is made through an examination by a mental health professional, a medical history, and a question and answer process. According to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), revised in 2013 by the American Psychiatric Association, the diagnostic criteria are as follows.

A. Characteristic symptoms

The presence of two or more of the following symptoms, at least one of which must be (1) delusions, (2) hallucinations, or (3) disorganised speech. The symptoms must be present for a significant portion of the month. (However, successful treatment may be for a shorter period of time).

(1) Delusions

(2) Hallucinations

(3) Disorganised speech (e.g., frequent derailment or disorganisation)

(4) Severely disorganised behaviour or catatonic behaviour

(5) Negative symptoms, i.e., emotional dullness, illogic, or anhedonia.

B. Reduced functioning in social, occupational, or other important areas due to symptoms

For a significant period of time after onset, the person’s level of functioning in at least one major area, such as occupation, interpersonal relationships, or self-care, is significantly reduced compared to before onset (if onset occurs in childhood or adolescence, the person does not achieve adequately in interpersonal, academic, or vocational areas).

C. Duration

Signs of the disorder must have been present for at least six months. This 6-month period must include at least 1 month of symptoms (active symptoms) that meet Diagnostic Criterion A (may be shorter if successfully treated), and may include prodromal and residual periods.

The prodromal or residual phase may include only negative symptoms or attenuated manifestations of two or more of the symptoms listed in Diagnostic Criterion A. The prodromal or residual phase may include only negative symptoms. (e.g., bizarre beliefs, unusual perceptual experiences).

D. Exclusion of schizoaffective disorder and mood disorders

Schizoaffective disorder and mood disorders with psychotic symptoms are excluded for the following reasons

(1) Major depressive or manic episodes do not occur concurrently with active phase symptoms.

(2) Or, if mood episodes do occur during the active phase, they are present for only part of the total duration of the active and residual phases of the illness.

E. Exclusion of Physiological Effects of Substances and General Medical Conditions

The impairment must not be the physiological effect of a substance, such as a drug of abuse or therapeutic medication, or due to a general medical condition.

F. Relationship to a developmental disability such as autism spectrum disorder

If there is a history of autism spectrum disorder or childhood-onset communication disorder, an additional diagnosis of schizophrenia may be made only if the distinct delusions or hallucinations persist for at least one month (but may be shorter if successfully treated).


Medication is the primary and essential treatment for schizophrenia. In addition, psychosocial treatment, including psychotherapy and psychosocial rehabilitation, has been reported to result in better treatment outcomes.

Education of the patient’s caregivers, including family members, is also very important.

For the pharmacological treatment of schizophrenia, antipsychotics were developed around 1950 to treat the symptoms associated with schizophrenia and have become the mainstay of treatment, and new drugs and new formulations have been developed continuously since then.

The first generation of antipsychotics had severe side effects and were not effective in treating negative symptoms, but newer antipsychotics, including second-generation antipsychotics with improved efficacy and side effects, and long-acting injectable formulations that can last for more than a month without medication, have been used in clinical practice to improve treatment outcomes.

Medication is effective in 70-80% of people with schizophrenia, but different types and doses of antipsychotics work for different people, and relapses may be less effective than initial treatment.

Inpatient treatment for people with schizophrenia may be considered when a clear diagnosis is needed, when intensive treatment such as medication changes or adjustments are needed, or when there is a risk of dangerous behaviour to others or oneself.

Day hospitals (a type of partial hospitalisation, in which a person attends a treatment programme in a hospital during the day and lives with their family at night) can be useful as a treatment programme that bridges the gap between inpatient and outpatient care.


Studies with five to ten year follow-ups after an initial inpatient treatment for schizophrenia show that 10-20% of patients have a good outcome. About half of patients have a poor outcome, which includes repeated hospitalisations, worsening symptoms, and depressive episodes.

However, not all people with schizophrenia have a poor outcome. It is estimated that 20-30% of patients are able to lead somewhat normal lives. The prognosis is worse than for patients with mood disorders.


There is no known way to prevent schizophrenia. Research and efforts are being made to prevent schizophrenia by identifying people at risk of developing schizophrenia, such as those with mild symptoms of schizophrenia, before they develop the illness.

Diet and lifestyle

There is no known diet to help with schizophrenia. It is important to maintain a regular lifestyle, and exercise, including aerobic exercise, has been shown to have many benefits, such as improving negative symptoms and weight loss.

Scroll to Top