The exact cause of autism is not known, but research has pointed to several possible factors, including genetics (heredity), metabolic or neurological factors, certain types of infections, and problems occurring at birth.
To date, there is no evidence that any vaccine can cause autism or any kind of behavioral disorder. A suspected link between the measles,mumps, rubella (MMR) vaccine and autism was suggested by some parents of children with autism, but well-documented, wide-ranging studies have discounted any association. One basis for the rejection of the theory is that typically, symptoms of autism are first noted by parents as their child begins to have difficulty with delays in speaking after age one. The MMR vaccine is first given to children at 12 to 15 months of age; autism cases with an apparent onset within a few weeks after the MMR vaccination may simply be an unrelated chance occurrence.