Page 482 - Understanding Psychology

Di?d You Know? Did You Know?
Split Personality The term schizophrenia comes from Greek for “split personality.” Schizophrenia does not refer to split per- sonalities such as dissociative identity disorder, though. Schizophrenia involves a split between the intellectual and emotional parts of a single personality.
the reappearance of symptoms. Although recovery from schizophrenia is possible, no real cure for schizo- phrenia exists, and once an individual is diagnosed with schizophrenia, he or she may never escape from it.
CAUSES OF SCHIZOPHRENIA
What is the actual cause of schizophrenia? There are many theories, and just as certainly, there is disagreement among practitioners. In all likelihood, the ultimate cause is an interaction of environmental, genetic, and biochemical factors.
Biological Influences
Genetics is almost certainly involved in causing schizophrenia. One psychologist (Gottesman, 1991) summarized the results of more than 35 studies conducted in Western Europe from 1920 to 1987. As confirmed by others, he found that there is a 1 percent likelihood that anyone in the general population will develop schizophrenia. These odds, however, increase to 10 percent if schizophrenia is already in the family. Yet, even among identical twins, if one twin develops schizophrenia, only 48 percent of the twin’s siblings will develop it. This finding implies that
other factors in addition to heredity also have a role in the development of schizophrenia (see Figure 16.12).
In trying to define the role of genetics more precisely, researchers have studied children born into families where either parent or a parent’s sibling was diagnosed with schizo- phrenia. Across several studies, if one or more siblings are diagnosed with schizophrenia, other children in the family will later be diagnosed with the condition less than 2 percent of the time. That probability rises to 5.5 percent if a parent or sibling is diagnosed (Mortensen, et al., 1999). Even where both parents were later diagnosed as having schizophrenia, about 50 percent of the children show no signs of schizo- phrenia. In summary, these studies show that psychologists cannot specify the exact contribution hereditary factors make to schizophrenia (Carson & Sanislow, 1992).
Biochemistry and Physiology
The proper working of the brain depends on the presence of right amounts of many chemicals, from oxygen to proteins. Some psychologists believe that psychosis is due largely to chemical imbalances in the brain. According to some theorists, occasionally people are born with a nervous system that gets aroused very easily and takes a long time to return to normal. Such people might be particularly likely to get upset when they are stressed.
Figure 16.11 Catatonic Type
A person suffering from the catatonic type of schizophrenia can hold an unusual position for long periods of time. Is schizophrenia curable?
468 Chapter 16 / Psychological Disorders