The Broader Autism Phenotype

According to the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders), Autism Spectrum Disorder is a neurodevelopmental disorder categorized primarily by deficits in social communication and restrictive/repetitive behaviors that cause significant impairment. To be diagnosed with ASD, one must present with symptoms early on in their development. Typically, children are not diagnosed until after the age of 4, and though the DSM argues that a diagnosis can be made starting from 12 months depending on symptom severity, many argue that diagnosis in infants is unreliable using current methods.

In order to study Autism symptoms in younger children, Dr. Maggie Guy conducted a study utilizing EEG (electroencephalogram) imaging. In said study, Dr. Guy studied neural correlates of facial processing, as abnormal processing is a well documented aspect of ASD. Dr. Guy measured ERP’s (event related potentials) in three groups of infants. One group of 21 infants was considered to be high risk for developing Autism due to having an older sibling with the disorder, another group of 15 was considered high risk due to having Fragile X Syndrome, and the final group was considered to be low risk due to no known history of familial or personal disorders. The facial processing task in the study looked at familiar and unfamiliar faces and toys in order to focus on N290, which is a negative ERP component which shows a greater amplitude in reaction to faces versus other things. According to the results, the infants with Fragile X showed the largest response, while the low risk infants were in the middle with the high risk infants due to a sibling with Autism displayed the lowest response. These results suggest that the heightened response of infants with FXS may point towards a higher risk of developing later anxiety disorders, and the smaller response in other high risk infants may be explained by deficits in automatic face processing in those with Autism-like traits.

One may wonder what benefit studying younger siblings of children with Autism may have, as they’re not guaranteed to be diagnosed with Autism. Yet newer research points to the existence of something called the Broader Autism Phenotype within family members of someone with ASD. The Broader Autism Phenotype describes those that have subclinical traits of Autism, meaning they display social difficulties or restrictive behaviors, just not to a severity that qualifies for a diagnosis of ASD. These traits further indicate a genetic link in the disorder. Irregardless of whether or not these children with siblings with Autism themselves develop the disorder, they have a significant risk of struggling with social and emotional difficulties. According to Carolyn Shivers, whose team looked at 69 studies that include siblings that are at least age 5, these children are more likely to have social deficits. They tend to develop anxiety and depression as well, leading Shivers to state that 'typical' siblings alongside their siblings with Autism would benefit from early behavioral interventions.

Works Cited:

Rudy, Lisa Jo. “Parents of Autistic Children May Have Mild Autism Symptoms.” Verywell Health, 18 May 2018, www.verywellhealth.com/what-is-the-broad-autism-phenotype-260048.

“Siblings of Children with Autism Have Social, Emotional Problems.” Spectrum | Autism Research News, 10 Oct. 2018, www.spectrumnews.org/news/siblings-children-autism-social-emotional-problems/.

Guy, Maggie W., et al. “Neural Correlates of Face Processing in Etiologically-Distinct 12-Month-Old Infants at High-Risk of Autism Spectrum Disorder.” Developmental Cognitive Neuroscience, vol. 29, 2018, pp. 61–71., doi:10.1016/j.dcn.2017.03.002.

Diagnostic and Statistical Manual of Mental Disorders: DSM-5. American Psychiatric Association, 2013.