Research in this area is in its “infancy” (pun intentional) but if we can develop a screening process that can successfully predict Autism Spectrum Disorder (ASD) in infants, then the earliest interventions can be employed which may dramatically improve the prognosis of the infants identified as being high risk. The human brain undergoes the most dramatic changes in the first 2 years of life which further highlights the importance of early intervention. According to the CDC, most children are not diagnosed with ASD until after they are 4 years old.
Jessica Schmerler wrote a piece for the magazine Scientific American Mind called “Enhanced Visual Attention May Be Early Predictor of Autism.” She wrote about research being doing at the University of London, Birkbeck in their Babylab. These scientists believe enhanced visual attention may predict the development of autism symptoms at an early age. Jessica described a longitudinal study at the Babylab which included 82 high-risk infants (these infants have an older sibling diagnosed with autism) and 27 low-risk infants which were tested at 9 months, 15 months, and two years of age regarding both visual attention and autism symptoms.
During each session an animation was played to get the infants to focus on the center of the screen and then an image such as the one I have made below would appear. This test was called the “odd-one-out.”
The scientists tracked the infants’ gazes and
recorded the amount of time it took for them to look toward the odd target. The
9-month-old infants who were quickest at spotting the odd visual target were
more likely to exhibit early symptoms of autism according to the Autism
Observation Scale for Infants (AOSI) at both 15 and 24 months. The scientists
did state that even though enhanced visual perception in 9-month-old infants
can predict later symptoms of autism, this cannot predict the severity of
future symptoms.
What is so unique about this test is that it
looks for enhanced brain function
which is opposite of current standards to look for impaired function in infants! A contributing author of the
study and a developmental psychologist at King’s College London, Rachel Bedford,
stated “enhanced brain function is likely specific to autism and would provide
a more specific screening target.” This is the case because impaired brain
function can indicate a wide range of other neurological disorders, so this new
development may aid in early diagnosis of specifically autism.
Dr. Maggie W. Guy published an article entitled “Neural
correlates of face processing in etiologically-distinct12-month-old infants at
high-risk of autism spectrum disorder” in the Journal of Developmental Cognitive Neuroscience. In this article
she and her colleagues compared two groups of one-year old infants at high-risk
to develop Autism Spectrum Disorder (ASD) with 21 low-risk (LR) infants the
same age serving as the control group. I will summarize her study and all
findings, but I am particularly interested in her results regarding attentional
engagement as it connects most with the work being done at the Babylab.
The two high-risk groups utilized were (1.) 15 infants
already diagnosed with Fragile X syndrome (FXS) which is a genetic condition
that causes developmental delay and intellectual disability, and (2.) 21
infants with an older sibling diagnosed with ASD which puts them at a greater
risk of developing ASD as well; this group is referred to as ASIBs. The
experiment used ERPs (event-related potentials) obtained from EEG
(electroencephalography) recordings to gain insight into neural patterns. Dr.
Guy and her colleagues were especially interested in facial processing since
atypical facial processing is very common in people diagnosed with ASD, and
prior research has shown that abnormal EEG responses can be detected in infants
mere months after birth. They looked at three specific ERP components; the N290
which is linked with facial processing in the middle fusiform gyrus, the P400
which has also been argued to be important for facial processing (but not as
strongly as the N290), and the Nc which is a measure of attentional engagement.
The three ERP components were measured in response to novel stimuli (a female stranger’s
face and a new toy) and familiar stimuli (each infant’s own mother’s face, and
a familiar toy specific to each infant).
All 57 infants showed greater a N290 amplitude
to faces rather than toys. Interestingly, (and contradicting the researchers’
hypotheses) the results showed that the N290 amplitude was largest for the FXS
group, followed by the LR group, and last the ASIBs (smallest N290 amplitude
for ASIBs). There were no significant
differences between groups at the P400.
Regarding the amplitude of the Nc component, responses
were greatest in the LR and FXS groups. As hypothesized by the researchers, the
LR group showed a greater Nc response to novel rather than to familiar stimuli,
and the FXS group showed the opposite pattern (greater response to familiar
stimuli). In the discussion section of the article, the FXS group’s response
was thought to be the result of immature stimulus processing because a greater
response to familiar vs. novel stimuli is a finding most commonly reported in
LR infants under 12 months of age. The researchers expected the ASIBs to show
the same Nc response as the FXS group, but this group showed a very similar
response to both stimulus types.
The researchers believed the results found in
the FXS group may reflect emerging anxiety since FXS is highly comorbid with
it. According to the CDC’s statistics on FXS and comorbid conditions, 70% of
males and 56% of females with FXS also have anxiety. Maggie and her
colleagues stated on page 9 of their article that the “behavioral
characteristics of the FXS group indicate that including females in the sample
may have diluted (their) results.” This is because FXS symptoms are overall
more severe for males than for females.
This brings me to my takeaway from both Dr. Guy’s
work and the research being conducted at the Babylab; I strongly believe future
research should examine gender differences among infants at high-risk for ASD,
ESPECIALLY regarding FXS. I think it is important for you to know the gender
breakdown of Dr. Guy’s study: out of the 21 ASIBs, 18 were male (86%), out of
the 21 LRs, 16 were male (76%), and most importantly, 8 (53%) out of the 15
infants with FXS were male.
During Dr. Guy’s seminar she said there is a 20%
chance for ASIBs to develop ASD and between a 25-60% chance that infants with
FXS also develop ASD. In her paper, however, she cited a much higher percentage
on page 2- “the relation between FXS and ASD is well established, with 60-74%
of FXS cases meeting criteria for ASD.” I found conflicting statistics on the
CDC website. The CDC cites a much lower risk for ASIBs; “parents who have a
child with ASD have a 2%-18% chance of having a second child who is also
affected (CDC’s ASD Data and Statistics page).”
Works Cited
CDC’s ASD Data and Statistics webpage https://www.cdc.gov/ncbddd/autism/data.html
CDC’s FXS Data and Statistics webpage (includes the graph as well) https://www.cdc.gov/ncbddd/fxs/data.html
Guy, M.W., et al., Neural correlates of face
processing in etiologically-distinct 12-month-old infants at high-risk of
autism spectrum disorder. Dev. Cogn. Neurosci. (2017), http://dx.doi.org/10.1016/j.dcn.2017.03.002
Image of baby with NIRS headgear courtesy of the Centre for Brain and
Cognitive Development at the University of London, Birkbeck http://cbcd.bbk.ac.uk/node/165
Schmerler, Jessica. “Enhanced Visual Attention May Be Early Predictor of
Autism.” Scientific American, Scientific American Mind, 11 June
2015, www.scientificamerican.com/article/enhanced-visual-attention-may-be-early-predictor-of-autism/
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