NIH: For children with autism spectrum disorder (ASD), early diagnosis is critical to allow for possible interventions at a time when the brain is most amenable to change. But that’s been tough to implement for a simple reason: the symptoms of ASD, such as communication difficulties, social deficits, and repetitive behaviors, often do not show up until a child turns 2 or even 3 years old.
Now, an NIH-funded research team has news that may pave the way for
earlier detection of ASD. The key is to shift the diagnostic focus from
how kids act to how their brains grow. In their brain imaging study, the
researchers found that, compared to other children, youngsters with ASD
showed unusually rapid brain growth from infancy to age 2. In fact, the
growth differences were already evident by their first birthdays, well
before autistic behaviors typically emerge.
Autism spectrum disorder includes a range
of developmental conditions, such as autism and Asperger syndrome, that
are characterized by challenges in social skills and communication.
Scientists have long known that teens and adults with ASD have unusually
large brain volumes. Researchers, including Heather Hazlett and Joseph
Piven of the University of North Carolina, Chapel Hill, found more than a
decade ago that those differences in brain size emerge by about age 2
. However, no one had ever visually tracked those developmental
In the new study reported in Nature , Hazlett, Piven, and
their colleagues set out to collect that visual evidence. They examined
106 infants at high risk of ASD, based on an older sibling with that
diagnosis. Fifteen of the study’s high-risk infants went on to be
diagnosed with ASD at age 2. The study also included another 42 infants
with no family history of ASD and a low risk for the disorder. In all
groups, the infants were mostly white, had similar birth weights, and
comparable family backgrounds.
Each infant underwent detailed behavioral assessments for early signs
of ASD, such as trouble babbling or making eye contact, at 6, 12, and
24 months of age. At each visit, the researchers also used a magnetic
resonance imaging (MRI) scanner to capture detailed images of each
child’s brain while napping.
Between the first and second scans, or just 6 to 12 months into the
study, the MRIs showed something remarkable. There was a significant
increase in the surface area of the brains of kids who would later
develop ASD compared to other children. By age 2, the brains of these
kids were obviously larger. The researchers found that kids whose brains
grew the fastest also had the most severe social deficits.
But could these observations be translated into early diagnosis? To
begin looking for an answer, the researchers turned to machine learning.
They wanted to find out whether a computer could use features captured
in those MRI scans, including the surface area and volume of the brain,
to predict accurately which kids would develop ASD and which ones
wouldn’t. They found that 8 times out of 10, the computer got it right.
Importantly, the computer-derived algorithm relied primarily on the
changes in brain surface area between the ages of 6 months and 1 year to
make those calls .
If the new findings can be confirmed in more children, it may lead to
a much-needed new approach to early diagnosis for kids at high risk of
ASD. Piven says the findings also highlight that ASD doesn’t occur
suddenly and spontaneously, as sometimes incorrectly thought. Rather,
the disorder develops over time—beginning in the first year of life or
likely earlier—from genetic and environmental influences that the North
Carolina team and others are working hard to understand.
Why should the development of a larger brain lead to ASD? We don’t
really know yet. Perhaps in the process of molding the brain for optimum
function, it’s not just the expansion of neurons and synaptic junctions
that matter, but also the “pruning” that allows this complex
network—the most complicated structure in the known universe—to achieve
maximum efficacy for human abilities and social interactions.The
findings also add to evidence from studies in mice that ASD may be
related to abnormalities in the progenitor cells that allow the brain to
grow . The hope is that, as more is learned about ASD’s underlying
biology, researchers will make even greater strides toward improving its
diagnosis and discovering entirely new kinds of treatments to help
these kids and their parents.
 Magnetic resonance imaging and head circumference study of brain size in autism: birth through age 2 years. Hazlett HC, Poe M, Gerig G, Smith RG, Provenzale J, Ross A, Gilmore J, Piven J. Arch Gen Psychiatry. 2005 Dec;62(12):1366-76.
 Early brain development in infants at high risk for autism spectrum disorder.
Hazlett HC, Gu H, Munsell BC, Kim SH, Styner M, Wolff JJ, Elison JT,
Swanson MR, Zhu H, Botteron KN, Collins DL, Constantino JN, Dager SR,
Estes AM, Evans AC, Fonov VS, Gerig G, Kostopoulos P, McKinstry RC,
Pandey J, Paterson S, Pruett JR, Schultz RT, Shaw DW, Zwaigenbaum L,
Piven J; IBIS Network; Clinical Sites; Data Coordinating Center; Image
Processing Core; Statistical Analysis.Nature. 2017 Feb
 Regulation of cerebral cortical size by control of cell cycle exit in neural precursors. Chenn A, Walsh CA. Science. 2002 Jul 19;297(5580):365-9.
Autism Spectrum Disorder (National Institute of Mental Health/NIH)
Infant Brain Imaging Study
Heather Hazlett (University of North Carolina, Chapel Hill)
Joseph Piven (University of North Carolina, Chapel Hill)
NIH Support: National Institute of Mental Health; Eunice Kennedy
Shriver National Institute of Child Health and Human Development;
National Institute of Biomedical Imaging and Bioengineering