Medical Investigation of Neurodevelopmental Disorders Institute and Department of Psychiatry and Behavioral Sciences, School of Medicine, University of California, Davis, Sacramento, California.
Medical Investigation of Neurodevelopmental Disorders Institute and Department of Psychiatry and Behavioral Sciences, School of Medicine, University of California, Davis, Sacramento, California.
Biol Psychiatry. 2021 Mar 1;89(5):424-432. doi: 10.1016/j.biopsych.2020.10.013. Epub 2020 Oct 29.
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.
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.
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.
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.
横断面弥散加权磁共振成像研究表明，年幼的自闭症儿童的白质结构存在改变，与年长的自闭症患者不同。然而，目前尚不清楚这些差异是由于神经发育异常还是年轻和年长队列之间的抽样差异所致。此外，改变的白质发育与自闭症症状的纵向变化之间的关系尚不清楚。
我们使用纵向弥散加权磁共振成像，在大约 2.5 到 7.0 岁之间的 2 到 3 个时间点，对 125 名自闭症儿童和 69 名正常发育对照参与者进行了采集，我们直接检验了自闭症个体在整个儿童期存在白质发育异常的假设。此外，我们还试图确定白质扩散参数的变化是否与自闭症严重程度的纵向变化相关。
研究发现自闭症儿童胼胝体压部、上纵束、内囊和胼胝体体部的各向异性分数发育较慢。此外，在矢状层，随着时间的推移自闭症严重程度增加的自闭症个体的各向异性分数的发育轨迹较慢，而自闭症严重程度降低的个体则较快。在钩束中，自闭症症状严重程度降低的个体，其各向异性分数随年龄的增长也有更大的增加。
这些纵向研究结果表明，先前在年轻和年长自闭症队列之间的弥散加权磁共振成像测量值中报道的差异归因于白质发育的异常轨迹。自闭症严重程度增加、保持稳定或降低的个体之间白质发育的差异表明，这些功能差异与自闭症大脑中的纤维发育有关。
