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The detection and early treatment of the autistic child are considered two of the fundamental pillars to improve the situation of those affected by this disorder. The sooner the diagnosis is confirmed, the better the long-term outcome will be. As in most cases the symptoms of autism spectrum disorders (ASD) are already present between 18 and 24 months, the American Academy of Pediatrics advises universal screening of autism in that age range. However, only 20% of children are diagnosed before the third year of life. Time constraints and the lack of an effective and cost-effective diagnostic or screening tool for autism and related developmental delays have been identified as the primary culprits in the failure of primary care physicians to detect the disorder. The diagnosis is usually delayed until the symptoms are obvious and undeniable. This delay in diagnosis is in direct contradiction with the initial picture of behavioral symptoms: 30% of the parents of children with ASD suspected developmental problems before the child’s first anniversary; 50% at 18 months; And 80% at 2 years. Despite this, the median age of diagnosis in the United States remains 5.5 years. The delay of the diagnosis causes the consequent delay in the intervention and the treatment. This leaves a unique opportunity to improve the effectiveness of treatment and the results achieved.

From the earliest hours of life, babies with typical development exhibit preferential attention to people. They recognize and prefer the mother’s voice rather than that of another unknown woman, but they prefer the sound of it rather than silence. Newborns look preferentially at the faces that look at them instead of those that look elsewhere, and at 3 months they direct it to the eye region when they look at talking faces. Babies are also able to imitate a person’s facial gestures. This indicates that children with typical development are predisposed to interact with the social aspects of the world around them. In contrast, as far as babies with autism are concerned, available data indicate that this is not the case. The most reliable indicators for early diagnosis of ASD focus on disturbances of typical interaction with the social world: poor interaction with others and avoidance, do not respond when called by name, reduced eye contact, and inability to participate in imitation games and in reciprocal vocalizations.

In autism, deficits in eye gaze are a defining feature of the condition and a key item in standardized diagnostic tests. These deficits have been extensively demonstrated in eye-tracking studies; in electrophysiological reports; and, also in functional MRI studies. Children with ASD look less than control groups: the median gaze fixation is, in fact, less than half that shown by neurotypical and children with intellectual disability. The fixation of eyesight in children with ASD is correlated with their degree of social incapacity (assessed with standardized clinical instruments. Moreover, children with ASD also show more fixation in the mouth than controls. It is thought that the cause of social incapacity are the alterations of the usual mechanisms of adaptive social action that appear at a very early age.

Fixation of the gaze begins at the same time as in the neurotypical controls, but then decreases continuously, from the second month until reaching a level close to half that of the controls at 24 months. The deterioration in fixation of the gaze is already underway in the first half. The decline in gaze fixation in the first half of life is closely associated with the outcome of the diagnosis at 36 months of age. These developmental differences in the degree of preferential attention to the gaze of other people proved to be a reliable marker of diagnosis a year and a half before the children were diagnosed by conventional means and two and a half years before the diagnosis of certainty. In children with autism, the degree of decline in ocular fixation is a reliable predictor of the level of social incapacity: children whose ocular attention decreased faster also showed greater social disability at times.

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Modified from:  Klin A, Klaiman C, Jones W. 2015. Reducing age of autism diagnosis: developmental social neuroscience meets public health challenge. Rev Neurol 60: S3-S11

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Spanish Version: La mirada como rasgo definitorio del trastorno de espectro autista