Most parents of autistic children suspect that something is wrong by the time the child is 18 months old and seek help by the time the child is age 2. Children with autism typically have difficulties in:

• Pretend play
• Social interactions
• Verbal and nonverbal communication

Some children with autism appear normal before age 1 or 2 and then suddenly "regress" and lose language or social skills they had previously gained. This is called the regressive type of autism.

People with autism may:

• Be overly sensitive in sight, hearing, touch, smell, or taste (for example, they may refuse to wear "itchy" clothes and become distressed if they are forced to wear the clothes)
• Have unusual distress when routines are changed
• Perform repeated body movements
• Show unusual attachments to objects

The symptoms may vary from moderate to severe.

Communication problems may include:

• Cannot start or maintain a social conversation
• Communicates with gestures instead of words
• Develops language slowly or not at all
• Does not adjust gaze to look at objects that others are looking at
• Does not refer to self correctly (for example, says "you want water" when the child means "I want water")
• Does not point to direct others' attention to objects (occurs in the first 14 months of life)
• Repeats words or memorized passages, such as commercials
• Uses nonsense rhyming

Social interaction:

• Does not make friends
• Does not play interactive games
• Is withdrawn
• May not respond to eye contact or smiles, or may avoid eye contact
• May treat others as if they are objects
• Prefers to spend time alone, rather than with others
• Shows a lack of empathy

Response to sensory information:

• Does not startle at loud noises
• Has heightened or low senses of sight, hearing, touch, smell, or taste
• May find normal noises painful and hold hands over ears
• May withdraw from physical contact because it is overstimulating or overwhelming
• Rubs surfaces, mouths or licks objects
• Seems to have a heightened or low response to pain

Play:

• Doesn't imitate the actions of others
• Prefers solitary or ritualistic play
• Shows little pretend or imaginative play

Behaviors:

• "Acts up" with intense tantrums
• Gets stuck on a single topic or task (perseveration)
• Has a short attention span
• Has very narrow interests
• Is overactive or very passive
• Shows aggression to others or self
• Shows a strong need for sameness
• Uses repetitive body movements

All children should have routine developmental exams done by their pediatrician. Further testing may be needed if the doctor or parents are concerned. This is particularly true if a child fails to meet any of the following language milestones:

• Babbling by 12 months
• Gesturing (pointing, waving bye-bye) by 12 months
• Saying single words by 16 months
• Saying two-word spontaneous phrases by 24 months (not just echoing)
• Losing any language or social skills at any age

These children might receive a hearing evaluation, blood lead test, and screening test for autism (such as the Checklist for Autism in Toddlers [CHAT] or the Autism Screening Questionnaire).

A health care provider experienced in diagnosing and treating autism is usually needed to make the actual diagnosis. Because there is no biological test for autism, the diagnosis will often be based on very specific criteria from a book called the Diagnostic and Statistical Manual IV.

An evaluation of autism will often include a complete physical and nervous system (neurologic) examination. It may also include a specific screening tool, such as:

• Autism Diagnostic Interview - Revised (ADI-R)
• Autism Diagnostic Observation Schedule (ADOS)
• Childhood Autism rating Scale (CARS)
• Gilliam Autism Rating Scale
• Pervasive Developmental Disorders Screening Test - Stage 3

Children with known or suspected autism will often have genetic testing (looking for chromosome abnormalities) and may have metabolic testing.

Autism includes a broad spectrum of symptoms. Therefore, a single, brief evaluation cannot predict a child's true abilities. Ideally, a team of different specialists will evaluate the child. They might evaluate:

• Communication
• Language
• Motor skills
• Speech
• Success at school
• Thinking abilities

Sometimes people are reluctant to have a child diagnosed because of concerns about labeling the child. However, without a diagnosis the child may not get the necessary treatment and services.