Characteristics of ASD in Young Children

DSM-IV Criteria and Early Diagnosis

Children with autism and ASD over the age of 3 generally display characteristics of autism that map well onto the diagnostic criteria outlined in the Diagnostic and Statistical Manual of Mental Disorder (DSM-IV) (2000). It is not clear that DSM-IV criteria are equally applicable to children under age 3 and particularly younger than 2, however. Stone and colleagues (1999) have examined this question empirically in a group of two-year-olds diagnosed clinically with autism. 

DSM manual

Leeway will need to be made for the developmental immaturity of infants and toddlers with autism on items that discuss abnormalities of speech, peer interactions, and, perhaps, repetitive behaviors.  Fewer numbers of symptoms may well be present in children with autism who are younger than 3, and clinicians will have to use clinical judgment in making the diagnosis, rather than adhering rigidly to rules for diagnosis - like symptom counts developed for older children and adults.  It may also be the case that infants with other developmental disorder may demonstrate symptoms similar to those seen in infants with autism in the first year of life; follow-up and re-examination of the diagnosis after age 3 is extremely important. Clinicians may need to use the diagnostic criteria in an informed way when faced with children younger than 3. The DSM 5, published in 2012, provides diagnostic criteria for ASD that fit much better with the symptoms of ASD seen in toddlers and preschoolers.

DC:03R and Early Characteristics of ASD

To address concerns about the difficulties with the DSM-IV for the early childhood years, the Diagnostic Classification of Mental Health and Developmental disorder of Infancy and Early Childhood: Revised Edition (DC:0-3R) (2005) was developed and published by the Zero to Three organization. It is an evolving classification system that is based on expert consensus rather than empirical findings and is designed to complement, not replace the DSM-IV in identifying early mental health and developmental difficulties in children under the age of five. The classification system adds additional diagnostic categories not found in DSM-IV, for the purpose of clinical guidance and more detailed description of early childhood difficulties. Since it has not been empirically validated, it should not be substituted for the DSM-IV as a diagnostic standard for ASD.

A great deal of research has been done to explore the earliest signs of autism and when they can be detected. Several research strategies have been used to study these questions, including:

  • retrospective parent interviews,
  • examination of home video collected prior to diagnosis, and
  • most recently, prospective studies that follow infants at risk for autism through the window of time when autism emerges.

Strong consensus has been obtained across all research methods. Behaviors that consistently discriminate infants or toddlers with autism from those with non-autism developmental delays or typical development are orienting to name, eye contact, social referencing, interest in other children, joint attention, affect sharing, and imitation (see Rogers, 2009 for a review).

A 2010 study (Ozonoff et al.) that compared siblings of children diagnosed with ASD and typically developing infants found that the earliest characteristics of autism are not readily observed at six months, but emerge gradually between nine and twelve months of age. Observed characteristics, such as a lack of shared eye contact, smiling and communicative babbling, contribute to the consensus reached by previous research.