Distinct patterns of grey matter abnormality in AS and HFA

Post Reply New Topic

Here are some interesting findings from a study on grey matter differences and the pertinence of language development in AS and HFA.

Interesting stuff.

It begs the question, are the differences causative or a result of plasticity in the brain and how the brain is utilized?

Quite so - pity feral children are rare enough that we likely cannot readily get comparable scans.

Anybody know how / whether use patterns impact the brain? I know they do with bone shape and composition.

Horus, thank you for posting this!!

I have a paper to write for my atypical child development course due this January) and I want to argue that AS and autism are distinct disorders. Actually I think the DSM should acknowledge both the similarities and differences between the 'autism spectrum disorders'. Creating a category called autism spectrum disorders makes sense , but the separate disorders should be listed underneath within this category I don't think all the PDDs should be subsumed under the heading ASD's and be designated mild, moderate and severe ASD'S. I don't think theses disorders only very in terms of the severity of the disorders , I think there are qualitative differences as well.

I am going to look for the full-text of this article.

oopsI put very instead of vary and theses instead of these .....I am very sleep deprived....I had an exam today......anyways I found another similar article . I can't seem to post links to the full-text article (from my uni database) on this site if you but if anyone wants the full article, pm me. =)

Title Differential effects on white-matter systems in high-functioning autism and Asperger's syndrome.
Author McAlonan, G. M.1; Cheung, C.2; Cheung, V.2; Wong, N.2; Suckling, J.3; Chua, S. E.1
Affiliation (1)State Key Laboratory for Brain and Cognitive Sciences, University of Hong Kong, Hong Kong, China; (2)Department of Psychiatry, University of Hong Kong, Hong Kong, China; (3)Cambridge Brain Mapping Unit, Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom
Source Psychological Medicine: A Journal of Research in Psychiatry and the Allied Sciences. Vol 39(11), Nov 2009, pp. 1885-1893
ISSN 0033-2917
Electronic ISSN 1469-8978

Descriptors
Aspergers Syndrome* Autism* White Matter*
New Search Using Marked Terms: Use AND to narrow Use OR to broaden
Add to Current Search: Use AND to narrow Use OR to broaden

Abstract Background: Whether autism spectrum maps onto a spectrum of brain abnormalities and whether Asperger's syndrome (ASP) is distinct from high-functioning autism (HFA) are debated. White-matter maldevelopment is associated with autism and disconnectivity theories of autism are compelling. However, it is unknown whether children with ASP and HFA have distinct white-matter abnormalities. Method: Voxel-based morphometry mapped white-matter volumes across the whole brain in 91 children. Thirty-six had autism spectrum disorder. A history of delay in phrase speech defined half with HFA; those without delay formed the ASP group. The rest were typically developing children, balanced for age, IQ, gender, maternal language and ethnicity. White-matter volumes in HFA and ASP were compared and each contrasted with controls. Results: White-matter volumes around the basal ganglia were higher in the HFA group than ASP and higher in both autism groups than controls. Compared with controls, children with HFA had less frontal and corpus callosal white matter in the left hemisphere; those with ASP had less frontal and corpus callosal white matter in the right hemisphere with more white matter in the left parietal lobe. Conclusions: HFA involved mainly left hemisphere white-matter systems; ASP affected predominantly right hemisphere white-matter systems. The impact of HFA on basal ganglia white matter was greater than ASP. This implies that aetiological factors and management options for autism spectrum disorders may be distinct. History of language acquisition

This particular paper only supports different symptomology not different causality. A tumor in different areas of the brain will cause different issues even if it is a glioblastoma in both instances. If the cause of ASDs is white matter density anomalies, as this paper suggests, then the magnitude and placement of those anomalies are only variants of the same underlying neurological condition. So the argument for Asperger's versus HFA becomes one of terminology. You could just as easily call one left brain autism and the other right brain autism.

Are you familiar with Occam's Razor? It would suggest that insisting that Asperger's is a different disorder needlessly adds complexity to the issue. I would even question the author's statement that the etiology is different. The cause is white matter density anomalies. The presentation is a difference in language development. Treatment is of course different in the same way that a stroke victim's rehab is specific to the region of the brain damaged.[/quote]


One of the main purposes of having a taxonomic classification system is to be able to come up with the best possible intervention for individuals with different disorders .... so the fact that "treatment is of course different" is a very significant issue in terms of whether the two disorders should be considered distinct for classification purposes. Patients with strokes in different regions of the brain would all be identified as "stroke patients" but would be further classified according to the location of their damage , i.e. "left parietal damage " , 'right temporal lobe damage", and would be treated for their unique damage. This is similar to what I have suggested....that there should be an 'ASD' category, with the distinct disorders i.e. AS, HFA listed within the category. It would only be un-parsimonious to distinguish between AS and HFA if there were no qualitative differences and only quantitative differences (they vary in terms of severity and nothing else) between the two conditions. The research into whether or not there are qualitative differences between AS and autism has yielded contradictory results. I don't think it can be concluded at this point that there are no qualitative differences between the two. This article supports my position by demonstrating that the two disorders may have very different etiologies. The fact that there are white matter abnormalities in both (as well as grey matter abnormalities in both....see the OP's article) does not mean that the etiology is not different!! !! ! That is like saying (that is saying) that the etiology is the same because they both involve brain abnormalities. If you google disorders that involve abnormalities of white matter density you will see what I mean ! !! These abnormalities (the ones found in this study) are in very different regions of the brain...which is why the author suggests a "different etiology".

For those who are interested but don't remember much neurology off the top of their heads,

http://www.dana.org/news/brainwork/detail.aspx?id=6028 Basal ganglia

And for those who find that the quotes may as well be Greek, the only part I can figure out is that the second one says that HFA > AS > NT in terms of white matter in basal ganglia.

Aetiological = etiological (only more pompous sounding). Etiology is the cause of stuff (in this case autism). Yep, they opened that can of worms.

I hope someone who knows more about neurology than I do comes along and translates the rest, please and thanks.

One of the main purposes of having a taxonomic classification system is to be able to come up with the best possible intervention for individuals with different disorders .... so the fact that "treatment is of course different" is a very significant issue in terms of whether the two disorders should be considered distinct for classification purposes. Patients with strokes in different regions of the brain would all be identified as "stroke patients" but would be further classified according to the location of their damage , i.e. "left parietal damage " , 'right temporal lobe damage", and would be treated for their unique damage. This is similar to what I have suggested....that there should be an 'ASD' category, with the distinct disorders i.e. AS, HFA listed within the category. It would only be un-parsimonious to distinguish between AS and HFA if there were no qualitative differences and only quantitative differences (they vary in terms of severity and nothing else) between the two conditions. The research into whether or not there are qualitative differences between AS and autism has yielded contradictory results. I don't think it can be concluded at this point that there are no qualitative differences between the two. This article supports my position by demonstrating that the two disorders may have very different etiologies. The fact that there are white matter abnormalities in both (as well as grey matter abnormalities in both....see the OP's article) does not mean that the etiology is not different!! !! ! That is like saying (that is saying) that the etiology is the same because they both involve brain abnormalities. If you google disorders that involve abnormalities of white matter density you will see what I mean ! !! These abnormalities (the ones found in this study) are in very different regions of the brain...which is why the author suggests a "different etiology".[/quote]

What is interesting is that we could use this paper to argue endlessly for discarding Asperger's (all autism is a white matter density issue) or for keeping it (differences in presentation). That suggests that it is not definitive enough to make a strong case in either direction.

What is interesting is that we could use this paper to argue endlessly for discarding Asperger's (all autism is a white matter density issue) or for keeping it (differences in presentation). That suggests that it is not definitive enough to make a strong case in either direction.[/quote]

I agree that there is not conclusive evidence to make the conclusion that AS and HFA are distinct or that they are one and the same. I just don't think that they should get rid of the AS label (along with Retts Disorder etc.) until there is more clarity.

However the fact that both disorders are associated with white matter (the article I posted ) AND grey matter (the article Horus posted) abnormalities is not enough to argue for a similarity t =between the two disorders, if one is primarily affecting the left hemisphere and the other is primarily affecting the right hemisphere. All that means is that the cell bodies of neurons (grey matter) AND the connections between neurons (white matter) are affected in both conditions. This just means there are brain abnormalities in both conditions , which could be said about almost any “condition”.

Having said that I will reiterate that there IS other evidence that would suggest that the disorders are qualitatively similar (or one and the same) as well as other evidence that shows (qualitative) distinctions. I think it is too early to conclude anything as of yet.

that’s a good question though....and I'm not saying it has been definitively answered..... I’m just my general impression from what I've read....but I've never specifically investigated it............