Autism: a complex diagnosis

There is no blood test or other biological marker for autism. Doctors rely on their own observations and what parents tell them. Psychiatry's guidebook, the Diagnostic and Statistical Manual of Mental Disorders, lays out the criteria. Many autistic traits and behaviors are seen in children without autism or with other conditions. Only in sufficient numbers and specific combinations do they add up to a diagnosis on the autism spectrum.

Stories: Discovering autism

The three most common diagnoses on the spectrum are autistic disorder, Asperger's disorder and — for children who don't qualify for those — pervasive developmental disorder not otherwise specified (PDD-NOS). As this interactive checklist illustrates, there are many ways to arrive at each, and how a child is classified can amount to a judgment call. Answer questions below or select a hypothetical case to explore how a diagnosis is reached.

Pervasive developmental disorder (PDD-NOS)
Asperger's disorder
Autistic disorder
Hypothetical cases:
Introductory questions

Were delays in social interaction, language or imaginative play apparent before age 3?

Were there delays in cognitive development, acquisition of self-help skills or emergence of interest in surroundings?

Social impairment
Problematic nonverbal behaviors.

Avoiding eye contact, not returning a smile, maintaining a blank gaze, using inappropriate facial expressions or awkward body postures.

Failure to interact appropriately with peers or make friends.

Playing alone while other children the same age approach each other, cooperate and imitate each other.

Problems sharing interests, achievements or pleasure with others.

Failing to show off creative projects such as finger paintings or respond to a companion's interests, such as a plane overhead.

Problems responding to social and emotional cues.

Failing to wave hello and good-bye, show concern for others or get excited about opening presents or seeing a parent come home from work.

Communication impairment
Delay or absence of speech with no attempt to compensate by using gestures.

Failing to point, nod head for "yes" or shake head for "no."

An inability to carry on a conversation even when speech is adequate.

Can answer questions or talk about personal interests, but does not ask questions or show interest in others.

Stereotyped and repetitive language.

Parroting phrases from books, videos, music or another person, while not forming original sentences.

Lack of imaginative play.

Not pretending, for instance, to drink from a teacup or paddle a boat down the river.

Repetitive behaviors or interests
An interest of intense or abnormal focus.

Fixating on a particular toy or the same video or TV show.

Rigid adherence to a routine or ritual that has no purpose.

Lining up toys, insisting on the same route to the grocery store or requiring family members to sit in the same places.

Repetition of particular movements or gestures.

Hand-flapping, clapping, rocking, pacing, walking on tiptoe, spinning, chewing on clothing or biting hands.

Persistent preoccupation with parts of objects.

Focusing on a doll's eyes or the spinning wheels of a car, or the smell of an object.

Likely Diagnosis

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Autistic disorder

Asperger's disorder


Credits: Anthony Pesce, Doug Stevens and Alan Zarembo