New Findings in Schizophrenia Research
Schizophrenia is more common in individuals born in the wintertime. This lead scientists to suspect that it was caused by a virus. A person's immune system is not as strong in cold weather, and therefore a winter newborn is more susceptible to infections.
The hypothesis of a viral cause of schizophrenia seemed to be bolstered by findings that the strongest genetic markers that predict schizophrenia code for proteins in the immune system.
But as scientists investigated further, the immune systems role in schizophrenia seems to have nothing to do with infections, viral or otherwise.
It appears that the immune system plays a non-immunological role in the brain. Specifically, the immune system appears to mediate the process of synaptic pruning. Synaptic pruning is where unneeded connections between neurons are removed. Such an unneeded connection is "labeled" for elimination in a manner similar to how a infectious bacterium is "labeled" for elimination.
Dysfunction in this part of the immune system could therefore cause the process go haywire and end up pruning far too many neural connections, as is seen happening in a part of the brain called the "pre-frontal cortex" of schizophrenia patients.