The Autism Society of America states that,
Autism can be diagnosed in infants as young as 1 year-old by observation using proper questionnaires and screening tools. There is no medical or blood test for autism. A developmental pediatrician, neurologist or psychiatrist familiar with developmental disorders can make a diagnosis.
Studies have shown that early diagnosis and early intervention lead to significantly improved outcomes and better levels of functioning for children with autism as they become adults.
Some early signs of autism include:
* Total lack of or delay in developing spoken language
* Stereotyped or repetitive use of language
* Little or no eye contact
* Lack of interest in peer relationships
* Lack of spontaneous or make-believe play
* Repetitive motor mannerisms (e.g., hand-flapping, finger-flicking, twirling objects, complex whole body movements)
* Persistent preoccupation with parts of objects
* Inflexible adherence to specific, nonfunctional routines or rituals
Source: Autism Society of America (ASA)