Very early diagnosis of autism spectrum disorder

The diagnosis of autism spectrum disorder (ASD) is made in individuals who differ widely in social and cognitive abilities, and also underlying or associated neurological and genetic conditions. The American Psychiatric Association’s DSM-5 revision of the diagnostic criteria was designed in part to clarify and reduce the range of presentations that are consistent with ASD, but broad variation is still present. Yet the ASD construct remains widely recognized as useful to help make sense of complex clinical situations and organize effective management and follow-up. According to DSM-5 criteria, ASD symptoms must be present from ‘the early developmental period’, though it is acknowledged that they may not become manifest until social demands exceed the child’s limited capacities. Indeed, diagnosis is still made late in many children, with a mean age between 38 months and 120 months, although most parents report concerns from around 12 months. In practice, this lag time limits access to appropriate management. Various approaches have been made to identify patterns of clinical characteristics in infants who go on to develop classical manifestations of ASD. Retrospective studies based on parental report and home video have illustrated interesting points despite limitations associated with recall bias and lack of appropriate control. Prospective longitudinal studies of groups at increased risk have been carried out in children who required neonatal intensive care and were later ascertained as having ASD, or in siblings of children with ASD. Those methodologically stronger studies must be carefully interpreted, knowing that they often lack an appropriate comparison group of infants at risk, and that the studied children may not be representative of ASD. Prospective community-based studies have also been conducted. All these approaches have pointed to such signs as abnormal eye contact, poor visual tracking, reduction in social smiling, response to name, expression of positive affects and social interests, imitation, and communication gestures between 12 months and 24 months. These observations in the second year of life contribute to a better understanding of natural history, while highlighting clinical red flags rather than providing sufficient elements for early diagnosis of ASD. Currently, the Autism Diagnostic Observation Schedule (ADOS-2) toddler module is arguably the most adequate diagnostic tool for ASD in this age group; however, the child requires sufficient motor skills to interact with the instrument material and be able to walk. Therefore, this assessment is not applicable in many (even typically developing) children at the 12 months lower limit mentioned in the manual. The question remains: is it possible to make the diagnosis of ASD very early in the hope – yet to be substantiated by an evidence base – that a timely intervention could then lead to better outcomes? Unfortunately, infants do not show patterns typically described in older children with ASD. None of the clinical risk markers described in early post-natal life (such as atypical visual tracking and attention, or persistence of visual preference for high amounts of stimulation) have been found to be strongly predictive. Detection must not be mistaken for diagnosis. Moreover, 20% appear to develop typically in the first year of life. At any rate, evidence is lacking to support the effects of intervention on ASD outcomes in the first year of life. Even considering a diagnosis of ASD at this stage may place an unnecessary burden on families. Do we need such a diagnosis in infants showing these atypical features to acknowledge parents’ concerns, place our observation in context, and offer access to resources designed to support the child and parents? Can early clinical acumen without a formal diagnosis of ASD optimize parenting, promote development, and avoid moral attributions (e.g. the child is lazy, stubborn, ungrateful)? The value of such an approach in the ‘post-diagnostic’ era should be evaluated and compared to interventions that specifically target deficits in social development, whether these turn out to be ASD or not.