Familial risk of autism alters subcortical and cerebellar brain anatomy in infants and predicts the emergence of repetitive behaviors in early childhood.
Inês Pote, Siying Wang, Vaheshta Sethna and 12 others
PMID 30801993WHAT IT FOUND
Infants with an older sibling diagnosed with autism showed larger subcortical and cerebellar brain volumes at 4-6 months.
These early structural differences correlated with repetitive behaviors observed at 36 months, suggesting brain anatomy changes precede behavioral symptoms in high-risk groups.
Key findings
01High-risk infants had significantly larger cerebellum and subcortical volumes at 4-6 months compared to low-risk infants.
02Within the high-risk group, larger subcortical volume at 4-6 months was positively correlated with restricted and repetitive autistic behaviors at 36 months.
03Cerebellar volume at 4-6 months was also significantly correlated with restricted and repetitive behaviors at 36 months in the high-risk group.
STILL TO COME
How it was doneWhat they found
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What it does not show
The sample size was small (50 infants), limiting statistical power and generalizability. Behavioral outcome data was collected only for the high-risk group at 36 months, preventing direct comparison of symptom trajectories with the low-risk group. MRI resolution was low, preventing analysis of smaller sub-regions within the cerebellum and subcortical areas. The study was not powered to distinguish between high-risk infants who develop ASD and those who do not; the four diagnosed cases drove some results. No correction for multiple comparisons was applied to the primary volumetric or correlation analyses, increasing the risk of false positives. Mother-infant interactions were observed only once in a research setting, which may not reflect natural behavior.
Declared interests
The study was funded by the National Institute for Health Research (UK), Medical Research Council, Simons Foundation, Autistica, and the European Union's Seventh Framework Programme. EU-AIMS received support from the Innovative Medicines Initiative, with contributions from pharmaceutical industry associations (EFPIA) and Autism Speaks. Authors are part of the EU-AIMS consortium.
The easy way to misread this
Do not interpret these brain volume differences as a diagnostic tool for individual patients. The study identifies group-level associations in a small sample, and the differences are subtle. Furthermore, the association between brain structure and behavior varied depending on whether the four infants diagnosed with ASD were included in the analysis, indicating that the findings may not apply uniformly across all high-risk infants.