Schizophrenia
is a no-fault, equal-opportunity illness most likely caused by a number of
factors, both genetic and environmental. Most scientists now accept a two-hit
theory for the cause of schizophrenia, which suggests that the genetic
susceptibility is compounded by one or more environmental factors:
Genetic
susceptibility: Based on family genetic history, some people are more
vulnerable to the disorder than other people are.
Environmental
factors: In someone genetically predisposed, certain environment factors may
come into play, such as:
• Physical trauma that occurs to the
fetus during childbirth
• Oxygen-deprivation or some
psychological or physical problem that occurs to the mother during pregnancy
and affects the developing fetus
• Emotional stress, such as the loss
of a parent or loved one during young adulthood.
Although
schizophrenia is genetically influenced, more than genetics is involved in its
development. Studies of identical twins show that, if one twin develops
schizophrenia, the other twin has only a 40 percent to 50 percent chance of also
developing the illness. There’s also an increased risk among fraternal twins
when one develops schizophrenia, the other has between a 10 percent and 17
percent chance, far less than that of identical twins. Having a parent with
schizophrenia also increases a person’s risk of developing the disease, to
about 10 percent. And if you have a sibling with the disorder — not your twin —
you have a 6 percent to 9 percent chance of developing the disorder yourself.
Scientists
still don’t know the precise causes of schizophrenia for any particular individual,
yet family members and patients themselves tend to dwell on (or even obsess
about) finding a “reason” or a “cause” for the illness. Although this instinct
is a natural one, finding the precise cause or explanation is impossible, not
to mention counterproductive — finding a reason doesn’t help treatment, and it
often creates unnecessary and misplaced guilt, with one family member blaming
another.
