 Schizophrenia is a complex and chronic disease that affects different aspects of cognition and behaviour, including attention, perception, thought processes, emotion and volition. Schizophrenia is a brain disease particularly involving decrement in gray matter as has been supported by findings from many imaging studies. The pathophysiology of these gray matter changes has not been clarified. Microglia activation is the consequence of virtually all conditions associated with neuronal injury. When activated following neuronal damage, microglia show a marked increase in the expression of peripheral type benzodiazepine binding sites which are particularly abundant on cells of the mononuclear macrophage. 