A PARTICULAR type of nerve cell, known as a glial cell, has been fingered as a cause of schizophrenia. The theory could help explain an abundance of disparate evidence for what triggers the disease.
Glial cells play a crucial role in the early development of the brain, and in adults they help support neurons, as well as fight infection. That makes them a prime suspect for involvement in schizophrenia, which affects 1 in 100 people, says Irving Gottesman at the University of Minnesota in Minneapolis.
Gottesman鈥檚 team in Germany and Iceland started their search by combing through the medical literature. In regions associated with schizophrenia they found 41 genes thought to code in some way for growth factors, such as insulin and glutamate, which affect the development of glial cells with varying degrees of significance (see Graphic).
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The team think that some of the genes could be making deficient growth factors. The resulting unhealthy glial cells in turn may weaken synaptic communication between brain cells, making an individual more susceptible to schizophrenia.
Their theory also goes a step further. Although genes may predispose some people to schizophrenia, many researchers suspect viruses may tip the balance. Gottesman and his team think that this happens because viral infections further weaken glial cells that are already damaged. Communication between the brain cells then breaks down to such a degree that schizophrenia is the result. Glial cells is where genetics and the environmental come together, the groups suggests in the online journal BMC Psychiatry (2002, 2:8).
The theory helps explain a number of studies in schizophrenia, the team say. For instance, why people with the condition tend to have certain abnormalities in their brain, and why some studies suggest the condition is triggered early in life, and possibly even in the womb. For example, one possible trigger is the human herpes virus-6, which targets glial cells and infects almost every child before the age of two.