Schizophrenia

Genes play an important role in causing schizophrenia, but they do not cause schizophrenia all by themselves. For this reason, many schizophrenia researchers believe that schizophrenia itself is not inherited, but rather only a risk for the disorder is inherited. They believe that people who have inherited a risk for schizophrenia will develop the disorder only if they are exposed to an environmental stressor (an event or condition in a person's surroundings that triggers an illness).

This theory is similar to that for other medical diseases, such as heart disease. For example, a person might inherit a risk for heart disease because he or she has a parent with heart problems. However, the person may or may not develop heart problems, depending on several environmental factors, such as the person's eating and exercise habits as well as the amount of daily stress he or she experiences.

Schizophrenia researchers are still working to find out what kinds of environmental stressors may combine with a genetic risk to cause schizophrenia. This mechanism would be similar to the way that an unhealthy diet can combine with a genetic risk to cause heart disease.

Biological Environmental Stressors

Several biological stressors have been studied as possible partial causes of schizophrenia. Several studies suggest that mothers of people with schizophrenia may have been exposed to a biological stressor while they were pregnant.

For example, severe outbreaks of the flu, such as the one that occurred in England in 1958, have been associated with an increase in the rate of schizophrenia twenty to thirty years later. It is possible that an unusually large number of unborn children were exposed to the flu virus during this time and that this exposure caused their brains to develop abnormally.

Some of these children may have also inherited a risk for schizophrenia. The genetic risk, combined with exposure to the flu virus, may have caused schizophrenia symptoms to be expressed when the child reached adulthood. Studies also reveal an increased rate of schizophrenia in people born during the spring and winter months in areas of the world with cold winters. Babies born during those seasons are more likely to have been exposed to the flu while in their mother's womb because there is a higher rate of the flu during the winter months.

Another early environmental stressor that may combine with a genetic risk to cause schizophrenia is a complication during the birth process. Researchers have found that people with schizophrenia are more likely to have suffered from birth complications (such as not getting enough oxygen during delivery) than people who do not have schizophrenia. Most babies born under these conditions, however, do not develop schizophrenia. It is likely that birth complications cause schizophrenia only if the person is also genetically at risk for the disorder.

Family Stress

At one time, many mental health professionals believed that schizophrenia was caused by family problems. In particular, many people believed that schizophrenia resulted from having a cold and unloving mother. The term “schizophrenogenic mother” was made up to describe these mothers who supposedly caused schizophrenia. There is no scientific evidence to support this theory. Having a mean and unloving family does not cause schizophrenia.

However, even though family stress clearly does not cause schizophrenia, some studies suggest that interactions with family members may affect the course of schizophrenia once a person has already developed the illness. As mentioned in chapter two, people who suffer from schizophrenia usually go through periods when their symptoms are better and other periods when their symptoms are worse. Symptoms can become so serious that the person has to go to the hospital. Some studies have shown that schizophrenia sufferers whose families are hostile and criticize them may be more likely to be hospitalized and to experience more periods of worsened symptoms.