Schizophrenia: What are the causes?

What do you think of when you think of schizophrenia?  Many people will think of someone who has multiple personalities.  Well, while movies and popular culture might portray schizophrenia as having such a symptom, a “split personality” is not usually the case (2).  There are many other different aspects of the disease.

Schizophrenia affects about 1.1 percent of the American population ages eighteen and older (1).  Symptoms of schizophrenia do not include a “split personality,” but rather a number of “positive” and “negative” symptoms.  “Positive” symptoms, which are easily noticed behaviors, include hallucinations and delusions, and disorders of thoughts and movement.  “Negative” symptoms refer to abnormal or inappropriate emotions and behaviors.

Hallucinations can be anything a person’s five senses detect that nobody else can because it is not real, although the most common type of hallucination in schizophrenia is hearing voices (1).  In many cases, these voices, or other types of hallucinations, may lead the individual into thinking thoughts that are neither true nor logical, called delusions.  Delusional beliefs are permanent, and remain even when others use logic to try to persuade the individual to think clearly (1).  Schizophrenics with thought disorders have a much disorganized way of thinking.  Often the individual will have difficulty getting out all the words of a thought through speaking, or will stop in the middle of a thought and continue with another, making “word salads” (3).  There is also a form of schizophrenia called catatonic schizophrenia, where one of the symptoms include the individual’s movement to suddenly freeze, and hold that position until the muscles get tired and slowly fall into a resting position.  Other movement disorders include clumsiness and repetition of a certain motion, but catatonia now occurs less often than it did before schizophrenia could be treated (1).

Schizophrenics often have an apathetic look on their faces, or speak monotonously.  They lack emotion, energy, and interest, and are often unmotivated to do tasks (4).  They are perceived as anti-social because of this, and are also thought of as lazy when they neglect personal hygiene and other everyday activities most people do (1).  More negative symptoms of schizophrenia include inappropriate social skills and also not caring enough to be social.  This may cause the individual to be alone most of the time (4).

But what exactly are the causes of schizophrenia?  Is schizophrenia brought on by bad experiences that have happened to the individual (environmental), or is there a chemical disorder within the body caused by genetics?

Research has gone to show that schizophrenia is the result of both genetic factors and environmental influences (5).  While there is only about a one percent chance an individual of the entire population will develop schizophrenia, the risk increases to ten percent when an immediate family member has the illness, and goes up to forty percent if both parents or an identical twin has schizophrenia (3).  However, about sixty percent of the people diagnosed with schizophrenia do not have relatives with the disease, so genetics is not always a factor (3).

Studies also show that factors such as the season of a child’s birth or if the mother was exposed to viruses during pregnancy also increases the chance for the child developing schizophrenia (3).  Also, in large families where siblings are less than two years apart, the illness has been observed to be more frequent (3).  Environmental influences, such as stress, are also known to increase the risk of schizophrenia.  The prefrontal lobes of the brain are most affected by stress, and it is the part of the brain that is thought to be responsible for the disease (3).  There is no known cure for schizophrenia, but there are treatments for the symptoms that occur chemically in the body (5).

In April of 2006, the United Kingdom’s Institute of Psychiatry discovered an abnormality in the brains of schizophrenics by comparing scans of their brains to scans of volunteers who were not diagnosed with the illness.  They have found an error at the chemical junction of the nerve cells of schizophrenics’ brains, which causes the thought and movement disorders (6).  Normally, the branches of the nerve cells connect to other cells by using the chemical glutamate to activate the receiving cell’s NMDA receptor, and the message goes through that way.  In schizophrenics, much of this system fails to work, and therefore does not allow different parts of the brain to communicate with each other (6).  However, it is still unknown why this glitch even occurs in the first place (6).

There is still much unknown about schizophrenia.  Scientists are discovering the chemical effects it has on people, but it is still unclear what exactly causes the illness.  There are both genetic and environmental factors involved, but sometimes there is only a genetic factor, or only an environmental influence.


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1. NIMH: Schizophrenia

2. NCBI: The association of schizophrenia with split personality

3. Adam About: Schizophrenia

4. Schizophrenia Symptoms

5. NAMI: Mental Illnesses

6. BBC NEWS