Data from: Cortical thickness, surface area and subcortical volume differentially contribute to cognitive heterogeneity in Parkinson's disease

Parkinson's disease (PD) is often associated with cognitive deficits, although their severity varies considerably between patients. Recently, we used voxel-based morphometry (VBM) to show that individual differences in gray matter (GM) volume relate to cognitive heterogeneity in PD. VBM does, however, not differentiate between cortical thickness (CTh) and surface area (SA), which might be independently affected in PD. We therefore re-analyzed our cohort using the surface-based method FreeSurfer, and investigated (i) CTh, SA, and (sub)cortical GM volume differences between 93 PD patients and 45 matched controls, and (ii) the relation between these structural measures and cognitive performance on six neuropsychological tasks within the PD group. We found cortical thinning in PD patients in the left pericalcarine gyrus, extending to cuneus, precuneus and lingual areas and left inferior parietal cortex, bilateral rostral middle frontal cortex, and right cuneus, and increased cortical surface area in the left pars triangularis. Within the PD group, we found negative correlations between (i) CTh of occipital areas and performance on a verbal memory task, (ii) SA and volume of the frontal cortex and visuospatial memory performance, and, (iii) volume of the right thalamus and scores on two verbal fluency tasks. Our primary findings illustrate that i) CTh and SA are differentially affected in PD, and ii) VBM and FreeSurfer yield non-overlapping results in an identical dataset. We argue that this discrepancy is due to technical differences and the subtlety of the PD-related structural changes.

帕金森病（Parkinson's disease, PD）常伴随认知功能缺损，不过不同患者的缺损严重程度差异显著。近期，我们借助基于体素的形态测量学（voxel-based morphometry, VBM）证实，灰质（gray matter, GM）体积的个体差异与帕金森病患者的认知异质性相关。但基于体素的形态测量学无法区分皮层厚度（cortical thickness, CTh）与皮层表面积（surface area, SA），而这两项指标在帕金森病中可能各自受到独立影响。因此，我们采用基于表面的分析方法FreeSurfer对原有队列进行了重新分析，并开展了两项研究：①比较93名帕金森病患者与45名匹配对照者的皮层厚度、皮层表面积以及皮层下/皮层灰质体积差异；②探究帕金森病患者队列中，上述结构测量指标与六项神经心理学任务的认知表现之间的关联。
研究发现，帕金森病患者存在以下脑结构改变：左侧距状沟周围脑回的皮层变薄，病变范围延伸至楔叶、楔前叶及舌叶区域，同时累及左侧顶下小叶、双侧额中回喙部以及右侧楔叶；左侧三角部额下回的皮层表面积则出现增加。在帕金森病患者队列内部，我们观察到以下相关性：①枕叶区域的皮层厚度与词语记忆任务的表现呈负相关；②额叶皮层的表面积与体积和视空间记忆能力呈负相关；③右侧丘脑体积与两项词语流畅性任务的得分呈负相关。
本研究的核心发现表明，①帕金森病患者的皮层厚度与皮层表面积受影响的模式存在差异；②针对同一数据集，基于体素的形态测量学与FreeSurfer得到的结果并不重合。我们认为，这种差异源于两种分析方法的技术差异，以及帕金森病相关脑结构改变的细微性。