Signs of early autism might be found in the eyes

A new study published in Nature Communications shows that infants who are later diagnosed with autism react more strongly to sudden changes in light.

This finding provides support for the view that sensory processing plays an important role in the development of the disorder.

Despite being defined by symptoms in social communication, researchers are increasingly embracing the view that the earliest signs of autism may reside in more basic processes of brain development.

In the new study from Sweden, researchers investigated the pupillary light reflex in 9-10 month old infants. This reflex is a basic regulatory mechanism controlling the amount of light that reaches the retina.

The infants who fulfilled criteria for autism at three years of age constricted their pupils more than infants who did not fulfil autism criteria at follow-up checks. Moreover, the amount of pupil restriction in infancy was associated with the strength of autism symptoms at follow up.

"Earlier studies on older children with autism have suggested a weak pupillary light reflex in this group. These findings motivated us to assess the reflex in infant siblings of children with autism,” said lead author Terje Falck-Ytter of Uppsala University.

“Most of these infants develop typically, yet the probability of later being diagnosed with autism is considerably higher in this group than in the general population. Surprisingly, we found that in infancy, the group differences were in the opposite direction than in older children. We found stronger reflexes in the infants later diagnosed with autism than in controls.”

The findings are important because they point to a very basic function that has not been studied before in infants with later autism diagnosis, he said.

In total, 147 infants with an older sibling with autism took part in the study, of whom 29 met the criteria for autism at follow-up. The study also included a control group consisting of 40 infants from the general population.

"Currently, autism cannot be reliably diagnosed before 2-3 years of age, but we hope that with more knowledge about the early development of the condition, reliable diagnosis will be possible earlier, which should facilitate early access to intervention and support for the families. New knowledge about early development in autism may also provide new leads on strategies for early intervention," Falck-Ytter said.

According to Rachel Gomez, a supervisor at the Early Autism Project in Malaysia, other markers are more reliable and easier to identify than pupillary reflex.

“We usually recognise indications of autism by looking at a child’s developmental milestones. So not just the sensory aspect of it, but also the speed of development: social development, cognitive development, and physical development. What would trigger our concern is when they aren’t meeting these milestones,” she told Global Health and Travel.

“We would look for various red flags, which would give an indication of whether there is a concern. The pupillary reflex is a very small part of autism, and usually very difficult to check. It’s not really one of the main things we look out for. With the eyes, it’s more about whether the child is making eye contact or registering another person’s presence.” 

This story was originally published in the Global Health and Travel issue of October-November 2018.