Approximately one in 68 children is identified with some form of autism, from extremely mild to severe, according to the U.S. Centers for Disease Control. On average, diagnosis does not occur until after age four, yet all evidence indicates that early intervention is the best way to maximize the treatment impact. Various tests that look for signs of autism in infants have not been conclusive but a new exercise could improve early diagnosis, and also help reduce worry among parents that they did not intervene as soon as possible.
The two most widely used tests to measure symptoms, the Autism Observation Scale for Infants (AOSI) and the Autism Diagnostic Observation Schedule (ADOS), cannot be used before the ages of 12 or 16 months respectively. The AOSI measures precursors to symptoms, such as a baby’s response to name, eye contact, social reciprocity, and imitation. The ADOS measures the characteristics and severity of autism symptoms such as social affectation and repetitive and restrictive behaviors.
Now a group of scientists at the Babylab at Birkbeck, University of London think they have identified a marker that can predict symptom development more accurately and at an earlier age: enhanced visual attention. Experts have long recognized that certain individuals with autism have superior visual skills, such as increased visual memory or artistic talent.
The Babylab researchers undertook a longitudinal study in which they tested both visual attention and autism symptoms in infants at nine months, 15 months, and two years. They followed a group of 82 high-risk and 27 low-risk infants. High-risk babies have an older sibling diagnosed with autism; those with low-risk have no mental or medical conditions and no first-degree relatives with an autism diagnosis. The researchers measured infant markers of autism symptoms using the AOSI at nine and 15 months, and measured symptoms and behavioral characteristics using the ADOS at two years.
At each session, the investigators showed the babies a short animation that focused the child’s gaze at the center of a screen. Then an image would appear containing a target that was the “odd-one-out.” For example, in a circle of seven “X”’s an “O” or plus sign might appear. The researchers tracked the infants’ gazes, measuring the time it took for them to look toward the odd target.
The scientists then compared the proportion of trials in which the infants looked toward the target with their scores on the symptom scales. The data showed that visual search performance at nine months had significant positive correlation with AOSI scores. In other words, the kids who at nine months quickly identified the odd visual element were more likely to show early symptoms of autism on the AOSI test at 15 and 24 months. The researchers found, however, that visual search performance did not directly correlate with ADOS scores at two years. In essence, although enhanced visual perception at nine months can predict the presence of autism symptoms later, it does not predict future symptom severity.
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Category(s):Autism spectrum disorders
Source material from Scientific American
