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The first 1000 days of the autistic brain: a systematic review of diffusion imaging studies.

Conti E, Calderoni S, Marchi V, Muratori F, Cioni G, Guzzetta A - Front Hum Neurosci (2015)

Bottom Line: Of the 264 papers extracted, four were found to be eligible and were reviewed.Similar conclusions emerged from the other diffusion parameters assessed.These findings are reversed to what is generally found in studies exploring older patient groups and suggest a developmental course characterized by a shift toward hypo-connectivity starting at a time between two and four years of age.

View Article: PubMed Central - PubMed

Affiliation: Department of Developmental Neuroscience, Stella Maris Scientific Institute, IRCCS Stella Maris Foundation Pisa, Italy ; Department of Clinical and Experimental Medicine, University of Pisa Pisa, Italy.

ABSTRACT
There is overwhelming evidence that autism spectrum disorder (ASD) is related to altered brain connectivity. While these alterations are starting to be well characterized in subjects where the clinical picture is fully expressed, less is known on their earlier developmental course. In the present study we systematically reviewed current knowledge on structural connectivity in ASD infants and toddlers. We searched PubMed and Medline databases for all English language papers, published from year 2000, exploring structural connectivity in populations of infants and toddlers whose mean age was below 30 months. Of the 264 papers extracted, four were found to be eligible and were reviewed. Three of the four selected studies reported higher fractional anisotropy values in subjects with ASD compared to controls within commissural fibers, projections fibers, and association fibers, suggesting brain hyper-connectivity in the earliest phases of the disorder. Similar conclusions emerged from the other diffusion parameters assessed. These findings are reversed to what is generally found in studies exploring older patient groups and suggest a developmental course characterized by a shift toward hypo-connectivity starting at a time between two and four years of age.

No MeSH data available.


Related in: MedlinePlus

Summary of the results of studies exploring FA in ASD subject groups whose mean age was below 60 months. Tracts showing a significant difference between ASD and controls are shown, with blue boxes indicating higher FA in ASD and red boxes indicating lower FA in ASD. The black vertical bar in the middle of the boxplots shows the mean age of the ASD group; the lateral sides of the boxplots, show the SD; height of the boxplots represents the sample size, as referred to in the lower left corner.
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Figure 1: Summary of the results of studies exploring FA in ASD subject groups whose mean age was below 60 months. Tracts showing a significant difference between ASD and controls are shown, with blue boxes indicating higher FA in ASD and red boxes indicating lower FA in ASD. The black vertical bar in the middle of the boxplots shows the mean age of the ASD group; the lateral sides of the boxplots, show the SD; height of the boxplots represents the sample size, as referred to in the lower left corner.

Mentions: Three of the four studies measured FA values. Findings are discussed according to the identified connections as grouped into commissural fibers, projection fibers, (thalamocortical, corticofugal, and cerebellar), and association fibers (long and short range) (Catani et al., 2012). As FA is widely explored in most diffusion studies, in order to put our results into a developmental perspective, we compared the three selected studies with those exploring structural connectivity in older subjects, and in particular in ASD groups were the mean age was between 30 and 60 months (Figure 1).


The first 1000 days of the autistic brain: a systematic review of diffusion imaging studies.

Conti E, Calderoni S, Marchi V, Muratori F, Cioni G, Guzzetta A - Front Hum Neurosci (2015)

Summary of the results of studies exploring FA in ASD subject groups whose mean age was below 60 months. Tracts showing a significant difference between ASD and controls are shown, with blue boxes indicating higher FA in ASD and red boxes indicating lower FA in ASD. The black vertical bar in the middle of the boxplots shows the mean age of the ASD group; the lateral sides of the boxplots, show the SD; height of the boxplots represents the sample size, as referred to in the lower left corner.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4374458&req=5

Figure 1: Summary of the results of studies exploring FA in ASD subject groups whose mean age was below 60 months. Tracts showing a significant difference between ASD and controls are shown, with blue boxes indicating higher FA in ASD and red boxes indicating lower FA in ASD. The black vertical bar in the middle of the boxplots shows the mean age of the ASD group; the lateral sides of the boxplots, show the SD; height of the boxplots represents the sample size, as referred to in the lower left corner.
Mentions: Three of the four studies measured FA values. Findings are discussed according to the identified connections as grouped into commissural fibers, projection fibers, (thalamocortical, corticofugal, and cerebellar), and association fibers (long and short range) (Catani et al., 2012). As FA is widely explored in most diffusion studies, in order to put our results into a developmental perspective, we compared the three selected studies with those exploring structural connectivity in older subjects, and in particular in ASD groups were the mean age was between 30 and 60 months (Figure 1).

Bottom Line: Of the 264 papers extracted, four were found to be eligible and were reviewed.Similar conclusions emerged from the other diffusion parameters assessed.These findings are reversed to what is generally found in studies exploring older patient groups and suggest a developmental course characterized by a shift toward hypo-connectivity starting at a time between two and four years of age.

View Article: PubMed Central - PubMed

Affiliation: Department of Developmental Neuroscience, Stella Maris Scientific Institute, IRCCS Stella Maris Foundation Pisa, Italy ; Department of Clinical and Experimental Medicine, University of Pisa Pisa, Italy.

ABSTRACT
There is overwhelming evidence that autism spectrum disorder (ASD) is related to altered brain connectivity. While these alterations are starting to be well characterized in subjects where the clinical picture is fully expressed, less is known on their earlier developmental course. In the present study we systematically reviewed current knowledge on structural connectivity in ASD infants and toddlers. We searched PubMed and Medline databases for all English language papers, published from year 2000, exploring structural connectivity in populations of infants and toddlers whose mean age was below 30 months. Of the 264 papers extracted, four were found to be eligible and were reviewed. Three of the four selected studies reported higher fractional anisotropy values in subjects with ASD compared to controls within commissural fibers, projections fibers, and association fibers, suggesting brain hyper-connectivity in the earliest phases of the disorder. Similar conclusions emerged from the other diffusion parameters assessed. These findings are reversed to what is generally found in studies exploring older patient groups and suggest a developmental course characterized by a shift toward hypo-connectivity starting at a time between two and four years of age.

No MeSH data available.


Related in: MedlinePlus