 - People with autism and autism spectrum disorders have problems with communication, behavior, and socializing, and many also have intellectual and developmental disabilities. The cause of autism is not known, but previous research has suggested an association between autism and immune changes in the brain. Researchers are interested in using the experimental radioactive drug 11CPBR28, which attaches to a protein in the brain that is involved in immune changes, in positron emission tomography PET scanning of people with and without autism to see if there are greater immune changes in those with autism. 