What exactly is Autism spectrum disorders (ASDs) and why was it chosen in this study?

ASDs are developmental disorders with symptoms in three core areas: social functioning, communication, and restricted or repetitive behaviors. Pupillary response is something that is affected by ASDs and that is why it is the center of the study. Previous studies have been inconsistent with results, but this study did come out with consistent results relating pupillary response and ASDs.

What is PLR, and why might it be a suitable diagnostic tool for children with ASD and other neurodevelopmental disorders?

PLR, or pupillary light reflex, can be used to test the integrity of sensorimotor, neuronal competencies. While generally useful for trauma diagnosis, a PLR diagnostic may aid in providing “red flags” for additional neurological testing. For children, specifically with ASD, it may be difficult to voluntarily sit still. Making MRI and CAT scans a difficult process, and too costly for developmental check-ups (at, say, a pediatricians). However, PLR can be a useful and cheap tool for basic procedures, to see whether or not additional, more expensive testing needs to be pursued.

Why did Dr. Gang Yao decide to use pupillary light reflex when studying children with ASD?

Dr. Gang Yao used pupillary light reflex to study children with ASD because it was non-invasive. He could have studied baseline pupil size in children with ASD and compared that to control children, but this study was done before and there was not a significant difference between the two. When measuring PLR, he could test multiple children without having to worry about ethical issues because it was a non-invasive, ethical way to get data from participants.

What do the similar atypical PLR results between the ASD and NDD groups show?

The fact the children in both the ASD and NDD groups had similar atypical pupillary light reflexes suggests that PLR problems are associated with a wide range of neurodevelopmental disorders, not just autism.  It is possible that the PLR pathway, which consists of the retina, pretectal nucleus, Edinger-Westphal nucleus, and ciliary ganglion, is physiologically altered in similar ways in these different disorders.

It is often said that people with ASD have heightened, more intense senses than those without. Why would this make sense regarding pupil responses?

The pupil contracts when it is exposed to a flash of light, and then recovers to protect the eye from any damage. In a study done by Rubin in 1961, it was found that people (specifically children in this study) with ASD had a pupillary constriction speed that was significantly slower in children with autism than typical controls when stimulated using a constant light intensity. This would help explain why people with ASD experience more intense senses and react to bright lights more than normal controls; because their eyes do not adjust as quickly to changes in brightness.

What was an interesting result that came out of Dr. Yao’s Research?

The PLR latency age trend that occurred in TD children (and not in ASD or NDD subjects) was interesting. Yao mentions that this is obscure due to the stabilization of the visual cortical pathways, which predominantly occurs during the critical period six months postpartum. According to Lobato-Rincon et. al, the PLR to green wavelengths (compared to white, blue, and red stimuli) decreases with age (in typically developed individuals), suggesting a discrepancy in the parasympathetic system. Interestingly, their study may suggest that, with age, there is a higher prevalence of sympathetic versus parasympathetic function. Autonomic dysfunction has already been suggested in ASD individuals based on clinical criteria, and several studies (including Yao’s) suggest these results via PLR and HRV. These results suggest that there is a low baseline parasympathetic activity, and perhaps suggests evidence of elevated sympathetic capabilities, relative to TD patients.

What kind of children are more likely to get autism?

There are virtually no children that are “safe” from getting autism. 1 in 68 children will be diagnosed, with more male children being diagnosed than female. Other than the difference in number of males and females being diagnosed, any child is at risk for developing autism. There is no correlation found between autism and race, diet, ethnicity, etc.

What biological issue may account for the contrasting age trends of latency times between children with ASD and those who are typically developing?

White matter maturation is believed to be different in autistic children as compared to the control children.  This maturation is accelerated in ASD children who are younger than 4, but it is slowed down after they are 4 and older.  The slower white matter maturation in ASD would mean that the axons in the brain would have less myelination and signals sent through the nervous system would take longer to be sent and received, which could account for the increased latency seen in autistic children.

What is a future study that Dr. Yao and his team of researchers is interested in pursuing and why is this a study of interest?

Dr. Yao hopes to conduct a longitudinal infant sibling study. Participants will be the siblings of children with autism, and the PLR in the participants will be measured when the participants are 6-24 months old. This is an area of interest because there are genetic links to autism, therefore, siblings of children with autism are a high risk group. This study may provide insight into the validity of using PLR for early autism detection, which can then lead to more effective interventions.

What are some advantages of this type of testing (PLR)? How can PLR be modified for future studies?

This type of testing can be done in a high capacity of children. It is a non-invasive and fast 2 second test that can help determine the outcome of the child’s future. It is a simple, low-cost system that measures the involuntary reflex of the child. That means that the child cannot fake the outcome in any way because it is involuntary. This is cheaper, faster, and more accurate than the fMRI alternative.

How might the theoretical model be a useful tool for diagnosis of ASD or other neurological disorders?

By creating a model which represents the data of TD individuals, doctors would be able to detect PLR latency to by miniscule deviations not prior accounted for. In addition, in regard to understanding the sympathetic and parasympathetic functions of the pupil, the model will allow scientists to understand how much each system contributes to the pupillary responses of the autonomic nervous system.