Neural correlates of face processing among preschoolers with fragile X syndrome, autism spectrum disorder, autism siblings, and typical development.
Fragile X preschoolers show super-sized brain waves to all sights, while autism and autism siblings show weak face-specific N170 responses, giving you a cheap early biomarker.
01Research in Context
What this study did
Researchers recorded brain waves while preschoolers watched faces and objects. They compared four groups: kids with fragile X, kids with autism, siblings of kids with autism, and typically developing peers. The team looked for the N170, a brain spike that normally pops when we see faces.
What they found
Kids with fragile X showed big brain waves to everything, not just faces. Kids with autism and autism siblings had smaller face-specific N170 waves. The pattern gives each group a distinct neural signature that you can spot with a simple cap and 20 minutes of recording.
How this fits with other research
Waldron et al. (2023) watched the same four groups with eye-tracking and found kids with non-syndromic autism looked at faces less than kids with fragile X. The two studies line up: less looking pairs with weaker N170.
Geurts et al. (2008) used fMRI in older children and also saw different brain signatures for fragile X versus autism. Adams et al. (2024) now shows the split appears even in preschoolers and with cheaper ERP gear.
Klein et al. (2024) tried teaching social gaze to both diagnoses. Fragile X learners needed more practice trials than autism learners. That training study extends the current paper: the same brain difference that shrinks the N170 in autism also predicts faster learning of gaze shifts.
Why it matters
You now have a quick, low-cost way to tell fragile X from idiopathic autism before age five. If the N170 is tiny and the child avoids eyes, think autism first. If the brain waves are huge to every picture and the child still makes some eye contact, think fragile X. Match your teaching speed to the diagnosis: give fragile X learners extra gaze-shift cycles and keep reinforcers steady.
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02At a glance
03Original abstract
The current study examined patterns of event-related potential (ERP) responses during a face processing task in groups of preschoolers uniquely impacted by autism spectrum disorder (ASD), including (1) children with ASD; (2) children with fragile X syndrome (FXS); (3) children with familial risk for ASD, but without a diagnosis (i.e., ASIBs); and (4) a low-risk control (LRC) group. Children with FXS have a high incidence of ASD diagnoses, but there have been no studies of the ERP response to faces in children with FXS and little work focused on children with ASD who have cognitive impairment. The current study examined children's ERP responses to faces and houses in four groups: LRC (N = 28, age = 5.2 years), ASIB (N = 23, age = 5.5 years), FXS (N = 19, age = 5.82 years), and ASD (N = 23, age = 5.5 years). The FXS and ASD groups were characterized by the presence of cognitive impairment. Pictures of upright and inverted faces and houses were presented while recording EEG with a 128-channel system. The N170 occurred at about 200 ms post stimulus onset, was largest on the posterior-lateral electrodes, and was larger for faces than houses. The P1 and N170 ERP components were larger for the FXS group than for the other three groups. The N170 ERP amplitude for the ASD and ASIB groups was smaller than both the LRC and FXS groups, and the LRC and FXS groups had the largest N170 responses on the right side. No difference was found in N170 latency between groups. The similarity of the ASD and ASIB responses suggest a common genetic or environmental origin of the reduced response. Although children with FXS have a high incidence of ASD outcomes, they differed from ASD and ASIB children in this study. Specifically, the children with FXS were hyperresponsive to all stimulus types while the ASD and ASIB groups showed attenuated responses for specific stimuli.
Autism research : official journal of the International Society for Autism Research, 2024 · doi:10.1002/aur.3045