Mental Illness, Physical Cause

There is increasing evidence that certain psychological illnesses such as obsessive-compulsive disorder (OCD), depression and schizophrenia have biological causes. According to Susan Swedo, scientific director of the National Institute of Mental Health (NIMH), these diseases can have a genetic component, just like heart disease and cancer, or be triggered by the very same infections that cause other diseases.

The link between mental illness and infections was first discovered when researchers observed that some patients with rheumatic fever (a complication of strep throat that can affect the heart) also developed OCD-like symptoms. Since their initial observations, they have come across a total of 75 cases in which children with untreated strep infections suddenly began to practice obsessive-compulsive rituals, or children with mild OCD or Tourette's syndrome unexpectedly worsened after having strep or flu-like infections.

Scientists believe that when the immune system produces antibodies to counteract a strep infection, it may also damage part of the brain related to OCD in some individuals. Based on this theory, researchers have been giving children drugs that act on the immune system. Penicillin has also been used on a continuing basis for children with mild, strep-triggered OCD to prevent a recurrence of strep that could worsen their symptoms. All children that have received these treatments have shown dramatic improvement, suggesting that these mental diseases are no more "psychological" in nature than rheumatic fever.

About 1% of Americans suffer from schizophrenia. It was once thought that parents who put their children in mind warping no-win situations caused this disease, but, now, there is evidence of a viral cause. Scientists at the University of Southern California examined people born during the nine months after the 1957 Asian flu epidemic in Finland. They discovered that children whose mothers had the flu during the second trimester of pregnancy had a higher than normal rate of schizophrenia later in life. Other studies have found that toxoplasmosis, cold viruses, and positive-negative blood incompatibility between a mother and her unborn baby may elevate the risk of schizophrenia.

Depression in some people also seems to be linked to viruses. Scientists at the Free University of Berlin have discovered that some depressed patients are infected with the Borna disease virus. This virus causes cats and horses to become listless and apathetic.

It was once thought that mental illness was due to troublesome spirits or imbalanced bodily humours. More recently, it has been blamed on such things as harsh toilet training or bad parenting. Now, it appears that several psychological conditions may be largely physiological in origin.  Based on information in: American Health, March 1997