Etiologic Models of Schizophrenia: Research and Causes

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  • 0:05 Schizophrenia
  • 0:44 A Syndrome
  • 2:43 Etiology
  • 3:39 Causes
  • 5:19 Correlations
  • 7:00 Lesson Summary
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Lesson Transcript
Instructor: Natalie Boyd

Natalie is a teacher and holds an MA in English Education and is in progress on her PhD in psychology.

What causes schizophrenia? How does the disorder develop? In this lesson, we'll look at the etiology, or cause and development, of schizophrenia and factors that are correlated to it.


John sees and hears things that aren't there. His hallucinations are only part of the story. He also believes things that aren't true, even though there is evidence of their being false. For example, he thinks that there is a secret agency made up of spies from several countries, and that they are all watching him and listening in on his phone conversations.

John suffers from schizophrenia, a psychotic disorder that is characterized by hallucinations and delusions, or false beliefs even in the face of contradictory facts. Other common issues associated with schizophrenia include very low emotions and lack of motivation.

A Syndrome

Many people think of schizophrenia as a disease, but in fact, it is a syndrome. What's the difference? A disease is a medical issue that has symptoms attached to it, whereas a syndrome is a group of symptoms that show up together. Let's look at an example. John contracts chicken pox from his nephew. This is a disease; there are symptoms, but there's also an underlying medical condition, a virus that causes the symptoms.

Compare that to his schizophrenia. Because it is a syndrome, schizophrenia is characterized by a group of symptoms, but there isn't an underlying medical condition that doctors can point to. Sure, John has hallucinations and delusions, and he has low emotions and a lack of motivation. These are symptoms that led to his diagnosis of schizophrenia.

There are some things that doctors have seen in common in the brains of schizophrenic patients. For example, ventricles are spaces in the center of the brain that are filled with fluid. When doctors look at John's brain and the brains of other schizophrenics, they can see that their ventricles are larger than most normal people.

If schizophrenia were a disease, doctors could look at large ventricles and other issues in the brain and diagnose a patient with schizophrenia. However, because it is a syndrome, the enlarged ventricles are a symptom, not a diagnostic tool. In other words, when doctors see large ventricles on a patient, they can't tell whether that patient has schizophrenia or not, because large ventricles could be due to another condition.

But, when they see large ventricles on a patient who has been diagnosed with schizophrenia, they are pretty sure that it is due to the schizophrenia. It is a symptom of the syndrome. Because schizophrenia is a syndrome, any one symptom cannot be used to diagnose it. Instead, it is diagnosed by a group of symptoms, usually behavioral symptoms, like hallucinations and delusions, as opposed to medical symptoms, like large ventricles.


Despite being a syndrome, there is a large part of the scientific community interested in the etiology of schizophrenia. Etiology is the study of the causes or origination of a disease, though sometimes (like in the case of schizophrenia) it is used on a syndrome.

So what causes schizophrenia? Well, scientists aren't sure what the etiology of the disease is. Here's what they know for sure: Schizophrenia is caused by some combination of genetics and environmental factors. It usually develops in late adolescence or early adulthood, and is slightly more common in men than women.

But there are a lot of unknowns in the middle of those facts. For example, what are the specific genetic and environmental factors that cause schizophrenia? Is it more common in men because they are more likely to get it, or because they are more likely to be diagnosed with it? Scientists don't know the answer to these questions.


There are several factors that might contribute to causing schizophrenia:

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