Microglia dysfunction in schizophrenia: an integrative theory.

Schizophrenia is a devastating illness of unknown etiology. It is characterized by increased brain ventricular volume, suggesting a progressive neurodevelopmental condition. There is evidence suggesting a correlation between in utero viral exposure and subsequent occurrence of schizophrenia. Many neurotransmitter systems have been implicated as being dysfunctional in schizophrenia. There are also data suggesting immune system dysfunction in schizophrenia, and a negative correlation between schizophrenia and rheumatoid arthritis. Microglia are phagocytic immune cells in the central nervous system (CNS) derived from peripheral blood monocytes. They are involved in brain development, neuroproliferative and neurodegenerative activities, several CNS illnesses, and CNS viral immunity. They may also be involved in neurotransmitter regulation. The current theory postulates microglial dysfunction initiated by early CNS viral exposure results in the abnormal neural development and neurotransmitter dysfunction seen in schizophrenia.