A radioactive substance is injected into the blood, and the areas of the brain that are very reactive take it up to show how active each area is. It is typically used with radioactive 2-DG. It provides estimates of change in brain activity and brain activity in general. If only one twin has a diagnosis, the twins are said to be discordantIt can lead to schizophrenia if the COMT is associated with VA often, therefore reducing DA in the prefrontal cortex and leads to cognitive defects and untimately psychosis. Since the brain is not fully developed, the psychosis rises from 3% to 10% in smokers under 26%