An infant who doesn't say single words by 16 months of age. A toddler who doesn't say 2-word phrases by 24 months of age. There are many biologic causes, but none of them are unique to autism. There is a 3-8 percent recurrence risk if a family already has one autistic child. Use the guidelines from the American Academy of Neurology.
Early diagnosis focuses on behavior.
Early intervention is needed for optimal care. Second, another evaluation is needed to establish the diagnosis of autism. Serologic studies, to see if a child has been infected with herpes simplex, intrauterine rubella, or cytomegalic inclusion disease. Hearing tests, to determine if the language delay is due to a hearing problem. Neuroimaging, such as MRI, is performed if a structural brain lesions is suspected.