According to a California study, mothers who use selective serotonin reuptake inhibitors (SSRI's), a common medication for depression, during pregnancy have a higher rate of children with autism. The net effect of these drugs is to increase the amount of serotonin in neurons in the brain that use serotonin as their neural transmitter. There are studies that indicate that children with autism have higher levels of serotonin in their circulatory systems. Sounds good. But there are also studies that show that children with autism have lower levels of serotonin and often children with autism are given SSRI's to increase serotonin. Confused? Me too. Because I have seen children with autism in my clinic improve when they are given SSRI's. I do not know how to explain this. But I do know that in this study and others serotonin levels are measured peripherally in the blood usually. No one has demonstrated that peripheral measures of serotonin correspond to central levels in the brain. I am getting to the point that I want to see a study that finds something that doesn't cause autism.