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.

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白质发育与幼儿期自闭症严重程度变化相关的纵向研究

背景横断面扩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与年长的自闭症患者不同。然而，目前尚不清楚这些差异是否是由于非典型神经发育或年轻和年长队列之间的采样差异造成的。此外，白质发育改变与自闭症症状纵向变化之间的关系尚不清楚。方法 使用纵向扩散加权磁共振成像，在 125 名自闭症儿童和 69 名典型发育对照参与者的年龄在 2.5 至 7.0 岁之间的 2 至 3 个时间点上采集，我们直接检验了自闭症个体在整个过程中具有非典型白质发育的假设。童年。此外，我们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。结果 自闭症儿童的扣带束、上纵束、内囊和胼胝体压部各向异性分数发育较慢。此外，在矢状层中，与自闭症严重程度下降的个体相比，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。在钩束中，自闭症症状严重程度下降的自闭症患者的各向异性分数随着年龄的增长也有更大的增加。结论 这些纵向研究结果表明，先前报道的年轻和老年自闭症人群之间弥散加权磁共振成像测量的差异可归因于白质的非典型发育轨迹。自闭症严重程度增加、保持稳定或减少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。