Here is new research:
A new paper threatens to turn the world of autism neuroscience upside down. Its title is Anatomical Abnormalities in Autism?, and it claims that, well, there aren’t very many. ...Hundreds of papers proved wrong by this? Rarely does one study show that everyone is wrong about some supposed disorder, but this appears to be an example. The psychologists have taken some personality differences and bogus brain scans and falsely made a disorder out of it.
There was no evidence for between-group differences in any measures of gross anatomy or in specific brain regions including the amygdala, hippocampus, most segments of the corpus callosum, and the cerebellum, which have been implicated in previous anatomical studies of ASD.I think this is an important paper and one that the autism field will need to take very seriously. There are hundreds of studies claiming to have found differences in brain structure in autism, many with small sample sizes, and Haar et al’s failure to replicate almost any of these claims, is sobering.
These results suggest that many of the previously reported anatomical abnormalities are likely to be of low scientific and clinical significance… anatomical differences between high-functioning ASD and control groups (aged 6 – 35 years old) are very small in comparison to large within-group variability.
This suggests that anatomical measures alone are likely to be of low scientific and clinical significance for identifying children, adolescents, and adults with ASD or for elucidating their neuropathology.
Meanwhile, brain scans do show differences between dope smokers and normal brains. The same NY Times has a story about parents who help their kids smoke marijuana.
(The above figure shows two copies of one brain. It was not part of the research.)