Can Schizophrenia Be Due To Infection?


Can Schizophrenia Be Due To Infection?

Schizophrenia is a mental disorder characterized by impaired thinking, perception, and expression of emotion. Schizophrenics tend to experience hallucinations, delusions, mood swings and a generally altered view of reality. In some instances, there is a family history that strongly suggests a genetic predisposition. In others, there appears to be some environmental trigger. Although the condition usually doesn't become apparent until the late teens or the 20s, most researchers suspect it starts much earlier, possibly before birth.

Supportive evidence comes from epidemiological studies showing waves of schizophrenia cropping up in England, Wales, Denmark, Finland, and other countries at the same time. What could they have in common? The answer may be that a generation previously, these areas had all been subjected to flu epidemics about the time the mothers of these patients were pregnant. A study in The New England Journal of Medicine reported higher rates of schizophrenia in children born in crowded areas in cold weather, where one would similarly expect a higher incidence of respiratory infections. A link with polio virus has also been suspected, since the incidence of schizophrenia fell sharply in many countries following the introduction of polio vaccine.

A new Finnish report supports this possibility. Researchers followed up on pregnant Finnish women who had been infected with the polio virus in the 1950's and 60's. They wanted to determine if they were more likely to bear children who would subsequently develop schizophrenia than non-infected mothers. The results indicated that among the more than 13,500 people born during this period, schizophrenia was indeed much more frequent among those whose mothers had been exposed to polio virus five months before giving birth. This would have been during the second trimester, a very important period in activities responsible for the organization of fetal brain functions.

Another virus that has been implicated in schizophrenia is the Borna virus. All of these organisms are believed to infiltrate fetal brain tissue during crucial stages of its development. The resultant immediate impairment may consist only of disruption of neuronal connections with seemingly little significance. Their effects may not become apparent until early adulthood, as the brain starts to reach its full maturity

Patients with advanced schizophrenia often show a shrinkage of certain structures, particularly the cerebral cortex, thalamus, and limbic system. As a result, there is a compensatory increase in fluid filled cavities which can be as much as 50 per cent. A variety of neurochemical communicative processes may be affected without obvious pathologic changes: in some patients, this may be the legacy of a prenatal viral infection.

Further support for an infectious role comes from studies suggesting that certain cases of schizophrenia may result from disturbances in immune system function similar to those seen in rheumatoid arthritis and multiple sclerosis. In these autoimmune diseases, the immune system mistakenly attacks normal cells since their appearance may have changed as a result of some infection. In such circumstances, there is an increase in substances known as heat shock proteins, whose purpose is to help protect central nervous system and other cells from damage.

Several years ago, researchers noted that some schizophrenics had increased levels of antibodies to these heat shock proteins. It was suggested that these antibodies, which reflect a response to some prior infection, might harm central nervous system structures. These same antibodies have also been found to be increased in multiple sclerosis patients. In this disorder, symptoms are due to damage to the protective myelin sheath around nerves, which are believed to result from aberrant immune system responses. A German study has recently reported that 33 percent of schizophrenic patients had increased antibodies to two types of heat shock proteins, more than ten times greater than the three percent seen in healthy controls.

It is quite possible that any type of significant prenatal insult may result in some manifestation of schizophrenia if it occurs during a crucial period of brain development. Rubella infection, diabetes, poor nutrition, and pregnancy complications have all been implicated. It seems most likely that schizophrenia is determined by a genetic predisposition coupled with environmental factors. Some of these may be much stronger than others, and in certain instances, a combination of seemingly insignificant insults may be responsible.

Schizophrenia, autism, depression, and other affective disorders have all been observed to nm in families, and the focus in recent years has been on genetic factors in mental diseases. There is evidence that faulty DNA is partially responsible for the development of anxiety and panic disorders, as well as schizophrenia in some patients. If heredity alone were to blame, then identical twins would develop schizophrenia with a high degree of concordance. However, when one identical twin has schizophrenia, it will eventually occur in the other only 40 percent of the time.

Decades ago, because of Freud's influence, schizophrenia was often attributed to poor parenting, and mothers were even called "schizophrenogenic". Obsessive-compulsive disorder was also blamed on being too strict in toilet training, but it now appears that aberrant responses to infections are much more likely to be responsible.

The American Institute of Stress.

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