Data_Sheet_1_Clinical and cortical similarities identified between bipolar disorder I and schizophrenia: A multivariate approach.docx

BackgroundStructural neuroimaging studies have identified similarities in the brains of individuals diagnosed with schizophrenia (SZ) and bipolar I disorder (BP), with overlap in regions of gray matter (GM) deficits between the two disorders. Recent studies have also shown that the symptom phenotypes associated with SZ and BP may allow for a more precise categorization than the current diagnostic criteria. In this study, we sought to identify GM alterations that were unique to each disorder and whether those alterations were also related to unique symptom profiles.
Materials and methodsWe analyzed the GM patterns and clinical symptom presentations using independent component analysis (ICA), hierarchical clustering, and n-way biclustering in a large (N ∼ 3,000), merged dataset of neuroimaging data from healthy volunteers (HV), and individuals with either SZ or BP.
ResultsComponent A showed a SZ and BP < HV GM pattern in the bilateral insula and cingulate gyrus. Component B showed a SZ and BP < HV GM pattern in the cerebellum and vermis. There were no significant differences between diagnostic groups in these components. Component C showed a SZ < HV and BP GM pattern bilaterally in the temporal poles. Hierarchical clustering of the PANSS scores and the ICA components did not yield new subgroups. N-way biclustering identified three unique subgroups of individuals within the sample that mapped onto different combinations of ICA components and symptom profiles categorized by the PANSS but no distinct diagnostic group differences.
ConclusionThese multivariate results show that diagnostic boundaries are not clearly related to structural differences or distinct symptom profiles. Our findings add support that (1) BP tend to have less severe symptom profiles when compared to SZ on the PANSS without a clear distinction, and (2) all the gray matter alterations follow the pattern of SZ < BP < HV without a clear distinction between SZ and BP.

研究背景
结构神经影像学研究已发现，确诊精神分裂症（schizophrenia, SZ）与双相I型障碍（bipolar I disorder, BP）患者的脑部存在相似特征，二者的灰质（gray matter, GM）缺失区域存在重叠。近期研究还表明，相较于现行临床诊断标准，基于SZ与BP的相关症状表型可实现更为精准的疾病分类。本研究旨在识别两种疾病各自特有的灰质改变，并探究此类改变是否与独特的症状特征存在关联。

材料与方法
本研究针对包含健康志愿者（healthy volunteers, HV）、SZ患者及BP患者的大型合并神经影像学数据集（样本量约3000例），采用独立成分分析（independent component analysis, ICA）、层次聚类及多向双聚类方法，分析灰质模式与临床症状表现。

研究结果
成分A在双侧岛叶与扣带回区域呈现出SZ与BP患者GM水平低于健康志愿者的模式；成分B在小脑及小脑蚓部区域呈现出SZ与BP患者GM水平低于健康志愿者的模式，且上述两种成分在不同诊断组间无显著差异。成分C在双侧颞极区域呈现出SZ患者GM水平低于健康志愿者、BP患者GM水平介于二者之间的模式。对阳性与阴性症状量表（PANSS）得分及ICA成分进行层次聚类，未得到新的亚组。多向双聚类识别出样本内3个独特的个体亚组，这些亚组对应不同的ICA成分组合及按PANSS划分的症状特征，但未发现显著的诊断组间差异。

结论
上述多变量分析结果表明，诊断边界与结构性脑差异或独特症状特征并无明确关联。本研究结果为以下两点提供了佐证：（1）相较于SZ患者，BP患者在PANSS量表上的症状严重程度更低，但二者并无明确区分；（2）所有灰质改变均遵循SZ＜BP＜HV的模式，SZ与BP之间亦无明确差异。