Dougherty Chase C, Evans David W, Katuwal Gajendra J, Michael Andrew M
Autism and Developmental Medicine Institute, Geisinger Health System, 120 Hamm Drive, Lewisburg, PA 17837 USA.
Department of Psychology, Program in Neuroscience, Bucknell University, 701 Moore Avenue, Lewisburg, PA 17837 USA.
Mol Autism. 2016 May 24;7:28. doi: 10.1186/s13229-016-0089-5. eCollection 2016.
While asymmetry in the fusiform gyrus (FFG) has been reported in functional and structural studies in typically developing controls (TDC), few studies have examined FFG asymmetry in autism spectrum disorder (ASD) subjects and those studies are limited by small sample sizes, and confounded by cognitive ability or handedness. No previous work has examined FFG surface area or cortical thickness asymmetry in ASD; nor do we understand the trajectory of FFG asymmetry over time. Finally, it is not known how FFG structural asymmetry relates to ASD symptom severity.
In this study, we examined FFG volume, surface area, and cortical thickness asymmetry, as well as their cross-sectional trajectories in a large sample of right-handed males aged 7 to 25 years with 128 ASD and 127 TDC subjects using general linear models. In addition, we examined the relationship between FFG asymmetry and ASD severity using the Autism Diagnostic Observation Schedule (ADOS) and Gotham autism severity scores.
Findings revealed that while group differences were evident with mean leftward asymmetry in ASD and mean near symmetry in TDC volume and surface area, asymmetry for both groups existed on a spectrum encompassing leftward and rightward asymmetry. In ASD subjects, volume asymmetry was negatively associated with ADOS and autism severity score symptom measures, with a subset of rightward asymmetric patients being most severely affected. We also observed differential trajectory of surface area asymmetry: ASD subjects exhibited a change from leftward asymmetry toward symmetry from age 7 to 25, whereas TDCs exhibited the reverse trend with a change from near symmetry toward leftward symmetry over the observed age range.
Abnormalities in FFG structural asymmetry are related to symptom severity in ASD and show differential developmental trajectory compared to TDC. This study is the first to note these findings. These results may have important implications for understanding the role of FFG asymmetry in ASD.
虽然在典型发育对照组（TDC）的功能和结构研究中已报道梭状回（FFG）存在不对称性，但很少有研究考察自闭症谱系障碍（ASD）患者的FFG不对称性，且这些研究受样本量小的限制，并受到认知能力或利手的干扰。此前没有研究考察过ASD患者FFG的表面积或皮质厚度不对称性；我们也不了解FFG不对称性随时间的变化轨迹。最后，尚不清楚FFG结构不对称性与ASD症状严重程度之间的关系。
在本研究中，我们使用一般线性模型，对128名ASD患者和127名TDC患者组成的7至25岁右利手男性大样本，考察了FFG的体积、表面积和皮质厚度不对称性，以及它们的横断面轨迹。此外，我们使用自闭症诊断观察量表（ADOS）和哥谭自闭症严重程度评分，考察了FFG不对称性与ASD严重程度之间的关系。
研究结果显示，虽然ASD患者平均向左不对称，TDC患者平均接近对称，两组之间存在明显的组间差异，但两组的不对称性都存在于一个涵盖向左和向右不对称的范围内。在ASD患者中，体积不对称与ADOS和自闭症严重程度评分症状指标呈负相关，一部分向右不对称的患者受影响最严重。我们还观察到表面积不对称的差异轨迹：ASD患者从7岁到25岁表现出从向左不对称向对称的变化，而TDC患者在观察到的年龄范围内表现出相反的趋势，即从接近对称向向左对称变化。
FFG结构不对称异常与ASD症状严重程度相关，且与TDC相比显示出不同的发育轨迹。本研究首次指出了这些发现。这些结果可能对理解FFG不对称性在ASD中的作用具有重要意义。
