Some Numbers

Schizophrenia affects men and women equally, however its onset in women is typically five years later than with men. About 150 of every 100,000 persons will develop schizophrenia. Though it is a relatively rare illness, its early age of onset and the lifelong disability, emotional and financial devastation it brings to its victims and their families make schizophrenia one of the most catastrophic mental illnesses. Schizophrenia fills more hospital beds than almost any other illness, and Federal figures reflect the cost of schizophrenia to be from $30 billion to $48 billion in direct medical costs, lost productivity and Social Security pensions.

Theories About Causes

Theories about the causes of schizophrenia abound, but research hasn't pinpointed the origins.

In years past, psychiatric researchers theorized that schizophrenia arose from bad parenting. A cold, distant and unfeeling mother was called "schizophrenigenic" because it was believed that such a mother could, through inadequate care, cause the symptoms of schizophrenia. This theory has been discredited today.

Most scientists now suspect that people inherit a susceptibility to the illness, which can be triggered by environmental events such as a viral infection that changes the body's chemistry, a highly stressful situation in adult life, or a combination of these.

While scientists have long known that the illness runs in families and much recent research evidence supports the linking of schizophrenia to heredity. For example, studies show that children with one parent suffering from schizophrenia have an eight to 18 percent chance of developing the illness, even if they were adopted by mentally healthy parents. If both parents suffer from schizophrenia, the risk rises to between 15 and 50 percent. Children whose biological parents are mentally healthy but whose adoptive parentssuffer from schizophrenia have a one percent chance of developing the disease, the same rate as the general population.

Moreover, if one identical twin suffers from schizophrenia, there is a 50 to 60 percent chance that the sibling--who has identical genetic make-up also has schizophrenia.

But people don't inherit schizophrenia directly, as they inherit the color of their eyes or hair. Like many genetically related illnesses, schizophrenia appears when the body is undergoing the hormonal and physicalchanges of adolescence. Genes govern the brain's structure and biochemistry. Because structure and biochemistry change dramatically in teen and young adult years, some researchers suggest that schizophrenia lies "dormant" during childhood. It emerges as the body and brain undergo changes during puberty.

Certain genetic combinations could mean a person doesn't produce a certain enzyme or other biochemical, and that deficiency produces illnesses ranging from cystic fibrosis to, possibly, diabetes. Other genetic combinationscould mean that specific nerves don't develop correctly or completely, giving rise to genetic deafness. Similarly, a genetically determined sensitivity could mean the brain of a person with schizophrenia is more prone to be affected by certain biochemicals, or that it produces inadequate or excessive amounts of biochemicals needed to maintain mental health. Genetically determined triggers could also the development of part of the brain of a person with schizophrenia, or could cause problems with the way the person's brain screens stimuli, so that the person with schizophrenia is overwhelmed by sensory information which normal people can easily handle.

These theories arise from the ability of researchers to see the structure and activity of the brain through very sophisticated medical technology. For example:

• Using computer images of brain activity, scientists have learned that a part of the brain called the prefrontal cortex--which governs thought and higher mental functions--"lights up" when healthy people are given an analytical task. This area of the brain remains quiet in those with schizophrenia who are given the same task. Magnetic resonance imaging (MRI) and other techniques have suggested that the neural connections and circuits between the temporal lobe structures and the prefrontal cortex may be have an abnormal structure or may function abnormally.
• The prefrontal cortex in the brains of some schizophrenia sufferers appears to have either atrophied or developed abnormally.
• Computed axial tomography or CAT scans have shown subtle abnormalities in the brains of some people suffering from schizophrenia. The ventricles--the fluid-filled spaces within the brain--are larger in the brains of some people with schizophrenia.
• Successful use of medications that interfere with the brain's production of a biochemical called dopamine indicates that the brains of those with schizophrenia are either extraordinarily sensitive to dopamine or produce too much dopamine. This theory is strengthened by observing treatment for Parkinson's disease, caused by too little dopamine. Parkinson's patients, who are treated with medication that helps increase the amount of dopamine, may also develop psychotic symptoms.

Schizophrenia is similar in several respects to "autoimmune" illnesses -disorders like multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS or Lou Gherig's disease), caused when the body's immune system attacks itself. Like the autoimmune diseases, schizophrenia is not present at birth but develops during adolescence or young adulthood. It comes and goes in cycles of remission and relapse, and it runs in families. Because of these similarities, scientists suspect schizophrenia could fall into the autoimmune category.

Some scientists think genetics, autoimmune illness and viral infections combine to cause schizophrenia. Genes determine the body's immune reaction to viral infection. Instead of stopping when the infection is over, the genes tell the body's immune system to continue its attack on a specific part of the body. This is similar to the theories about arthritis, in which the immune system is thought to attack the joints.

The genes of people with schizophrenia may tell the immune system to attack the brain after a viral infection. This theory is supported by the discovery that the blood of people with schizophrenia contains antibodies--immune system cells--specific to the brain. Moreover, researchers in a National Institute of Mental Health study found abnormal proteins in the fluid that surrounds the brain and spinal cord in 30 percent of people with schizophrenia but in none of the mentally healthy people they studied. These same proteins are found in 90 percent of the people who have suffered herpes simplex encephalitis, an inflammation of the brain caused by the family of viruses that causes warts and other illnesses.

Finally, some scientists suspect a viral infection during pregnancy. Many people suffering from schizophrenia were born in late winter or early spring. That timing means their mothers may have suffered from a slow virus during the winter months of their pregnancy. The virus could have infected the baby to produce pathological changes over many years after birth. Coupled with a genetic vulnerability, a virus could trigger schizophrenia.

Most psychiatrists today believe that the above--genetic predisposition, environmental factors such as viral infection, stressors from the environment such as poverty and emotional or physical abuse--form a constellation of "stress factors" that should be taken into account in understanding schizophrenia. An unsupportive home or social environment and inadequate social skills can bring on schizophrenia in those with genetic vulnerability or cause relapse in those already suffering with the disease. Psychiatrists also believe these stress factors can often be offset with "protective factors" when the person with schizophrenia receives proper maintenance doses of antipsychotic medication, and help in creating a secure network of supportive family and friends, in finding a steady and understanding place of employment, and in learning necessary social and coping skills.

continue: Treatment of Schizophrenia