A pair of revolutionary studies at the UC Davis MIND Institute offer hints about probable types of autism associated with brain structure, including growth in size and white matter.
According to a report from Neuroscience, the twin research is based on scans conducted for many years "as part of the Autism Phenome Project or APP and Girls with Autism, Imaging of Neurodevelopment or GAIN studies."
The said research presents the value of longitudinal studies that monitor the same children from diagnosis to adolescence stage.
According to Christine Wu Nordahl, associate professor in the Department of Psychiatry and Behavioral Sciences, there is no other single location data set like theirs anywhere.
Nordahl, also a MIND Institute Faculty member and co-senior author on both research, added, "in one of the studies," the researchers had more than 1,000 magnetic resonance imaging or MRI scans from 400 children, "which is unheard of." It has been 15 years of work to reach this finding.
Big Brains, A Type of Autism
In the first research, which the Biological Psychiatry published, the study authors used MIR to follow brain size in around 294 children with autism and 135 kids without the condition between three to 12 years.
In those with autism, the study investigators found evidence of large-sized brains associated with height, or disproportionate megalencephaly, a sub-type associated with higher intellectual disability rates and poorer general prognosis.
Previous cross-sectional studies had shown that children with autism have bigger brains at early ages, although no evidence was presented of bigger brains in later childhood. The commonly accepted notion is that these brains either shrank or normalized as the kids grew up.
On the contrary, the research by the MIND Institute found that was not the case. It specified that children with bigger brains three years old still had larger brains at 12 years old.
The reason for this is that, unlike most studies, which investigate different individuals at different points of time, this particular research examined the same children over time in a longitudinal manner.
Bigger Brain Size Linked to Lower IQ
Different from most other studies, this specific work involves children suffering from substantial intellectual disabilities. These were the children with the tendency to have a large brain form of autism.
According to David Amaral, co-senior author on both studies recommended that the difference between their work and the previously-conducted ones was that children who have intellectual disability "were left out of past cross-sectional studies consecrated on older children."
Larger brain size in autism, he also said, has been associated with lower IQ, and children suffering from intellectual disabilities are more difficult to scan as these kids grow older.
Amaral, who's also a distinguished psychiatry and behavioral sciences professor, and a faculty member at MIND Institute, also said, "It's a matter of sampling bias, and the previous 'dogma' appears to be an artifact," of who among the children got scanned and when it happened.
Essentially, children aged below five years old can be scanned while they are sleeping. However, Nordahl and her team have developed unique, groundbreaking protocols that enable researchers to scan older children with intellectual disabilities more easily while they are awake.
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