A Longitudinal Study of White Matter Development in Relation to Changes in Autism Severity Across Early Childhood.
BACKGROUND
Cross-sectional diffusion-weighted magnetic resonance imaging studies suggest that young autistic children have alterations in white matter structure that differ from older autistic individuals. However, it is unclear whether these differences result from atypical neurodevelopment or sampling differences between young and older cohorts. Furthermore, the relationship between altered white matter development and longitudinal changes in autism symptoms is unknown.


METHODS
Using longitudinal diffusion-weighted magnetic resonance imaging acquired over 2 to 3 time points between the ages of approximately 2.5 to 7.0 years in 125 autistic children and 69 typically developing control participants, we directly tested the hypothesis that autistic individuals have atypical white matter development across childhood. Additionally, we sought to determine whether changes in white matter diffusion parameters were associated with longitudinal changes in autism severity.


RESULTS
Autistic children were found to have slower development of fractional anisotropy in the cingulum bundle, superior longitudinal fasciculus, internal capsule, and splenium of the corpus callosum. Furthermore, in the sagittal stratum, autistic individuals who increased in autism severity over time had a slower developmental trajectory of fractional anisotropy compared with individuals whose autism decreased in severity. In the uncinate fasciculus, autistic individuals who decreased in autism symptom severity also had greater increases in fractional anisotropy with age.


CONCLUSIONS
These longitudinal findings indicate that previously reported differences in diffusion-weighted magnetic resonance imaging measures between younger and older autism cohorts are attributable to an atypical developmental trajectory of white matter. Differences in white matter development between individuals whose autism severity increased, remained stable, or decreased suggest that these functional differences are associated with fiber development in the autistic brain.
['Andrews|Derek Sayre|DS|', 'Lee|Joshua K|JK|', 'Harvey|Danielle Jenine|DJ|', 'Waizbard-Bartov|Einat|E|', 'Solomon|Marjorie|M|', 'Rogers|Sally J|SJ|', 'Nordahl|Christine Wu|CW|', 'Amaral|David G|DG|']
D016880:Anisotropy D001321:Autistic Disorder D001921:Brain D002648:Child D002675:Child, Preschool D003430:Cross-Sectional Studies D038524:Diffusion Magnetic Resonance Imaging D006801:Humans D008137:Longitudinal Studies D066127:White Matter
Longitudinal White Matter Development Autism Imaging Diffusion