A direct connection exists between the brain and the immune system – at least in mice. Scientists at the Helmholtz Centre for Infection Research in Braunschweig conducted a comprehensive study of mice intestine and the surrounding blood and lymph vessels using special microscopy and marking techniques.
What they found: numerous immune cells imbedded in the tissue around the intestine are joined to nerve strands and cells. "We already have many indications that immune defenses are at least partially influenced by the nervous system," explains Helmholtz scientist Dr. Kurt Dittmar. "We have now seen these connections under the microscope." In all probability, says Dittmar, the situation in humans is not all that different to mice. The assumption is that the brain and psyche in mice have an effect on the immune system. "For many infectious diseases and autoimmune ailments," he says, "connections have been observed on a regular clinical basis between the psyche and the severity of an illness."
The Helmholtz researchers are not quite ready to speculate on the specific interactions at work. According to Dittmar, not enough is known about how the nervous system regulates immune defenses. "Research into the interactions involved is still in the early stages," he says, "but the cell connections studied could, in the near future, also lead to a better understanding of the paths of some infections, e.g. for prions that induce mad cow disease, which could enter the nervous system through the intestines."