Increased MRI-based cortical grey/white-matter contrast in sensory and motor regions in schizophrenia and bipolar disorder
Increased MRI-based cortical grey/white-matter contrast in sensory and motor regions in schizophrenia and bipolar disorder
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DOI：
10.1017/s0033291716000593
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发表时间：
2016-07-01
影响因子：
6.9
通讯作者：
Agartz, I.
中科院分区：
文献类型：
--
作者：
Jorgensen, K. N.;Nerland, S.;Agartz, I.
背景精神分裂症和双相情感障碍共享遗传风险因素，一个可能的发病机制是髓鞘形成异常。T1加权磁共振成像（MRI）组织强度对髓鞘含量敏感。因此，灰质和白质强度之间的对比可能反映了沿皮层表面的髓鞘形成沿着。MRI图像来自精神分裂症患者（n = 214）、双相情感障碍患者（n = 185）和健康对照组（n = 278），并在FreeSurfer中进行处理。在每个顶点处计算灰质/白质对比度，作为平均灰质强度（在皮质带中采样0-60%）和平均白质强度（在皮质下白色物质中采样0-1.5 mm）之间的差值，通过其平均值进行归一化。使用年龄和性别协变线性模型检验组间差异。与对照组相比，精神分裂症患者双侧中央前回和后回、颞横回和后岛叶以及顶枕区的对比度增加。在双相情感障碍中，对比度增加主要位于左侧中央前回。精神分裂症和双相情感障碍之间无显著差异。在调整皮质面积、厚度和回旋后，对比度增加的结果仍然存在。我们发现与抗精神病药物剂量无关。结论。在精神分裂症患者的高度髓鞘化的低级感觉和运动区发现对比度增加，在双相情感障碍患者中发现对比度增加的程度较低。我们认为这些发现表明皮质内髓鞘减少。根据推论放电假说，这可能会导致感觉输入的去抑制，导致扭曲的知觉处理，从而导致精神分裂症的特征性阳性症状。
Background. Schizophrenia and bipolar disorder share genetic risk factors and one possible illness mechanism is abnormal myelination. T1-weighted magnetic resonance imaging (MRI) tissue intensities are sensitive to myelin content. Therefore, the contrast between grey-and white-matter intensities may reflect myelination along the cortical surface.Method. MRI images were obtained from patients with schizophrenia (n = 214), bipolar disorder (n = 185), and healthy controls (n = 278) and processed in FreeSurfer. The grey/white-matter contrast was computed at each vertex as the difference between average grey-matter intensity (sampled 0-60% into the cortical ribbon) and average white-matter intensity (sampled 0-1.5 mm into subcortical white matter), normalized by their average. Group differences were tested using linear models covarying for age and sex.Results. Patients with schizophrenia had increased contrast compared to controls bilaterally in the post-and precentral gyri, the transverse temporal gyri and posterior insulae, and in parieto-occipital regions. In bipolar disorder, increased contrast was primarily localized in the left precentral gyrus. There were no significant differences between schizophrenia and bipolar disorder. Findings of increased contrast remained after adjusting for cortical area, thickness, and gyrification. We found no association with antipsychotic medication dose.Conclusions. Increased contrast was found in highly myelinated low-level sensory and motor regions in schizophrenia, and to a lesser extent in bipolar disorder. We propose that these findings indicate reduced intracortical myelin. In accordance with the corollary discharge hypothesis, this could cause disinhibition of sensory input, resulting in distorted perceptual processing leading to the characteristic positive symptoms of schizophrenia.