Department of Psychology, Simon Fraser University, Burnaby, Canada.
Department of Psychiatry, University of British Columbia, Vancover, Canada.
Brain Behav. 2019 Mar;9(3):e01233. doi: 10.1002/brb3.1233. Epub 2019 Feb 6.
We investigated white matter differences associated with distinct neurocognitive profiles derived from a large cohort of marginally housed persons with comorbid physical and mental illnesses. Our prior work identified three profile cluster groups: a high functioning group (Cluster 1), a low functioning group with relative strength in decision-making (Cluster 3), and an intermediary group with a relative decision-making weakness (Cluster 2). This study extends previous findings of cortical gray matter differences between these groups with evidence for putative neurodevelopmental abnormalities in the low cognitive functioning group (i.e., Cluster 3). We hypothesized that altered white matter diffusion would be associated with the lowest functioning neurocognitive profile and would be associated with previously observed gray matter differences.
Participants from a socially impoverished neighborhood in Vancouver, Canada underwent neurocognitive evaluation and neuroimaging. We performed Tract-Based Spatial Statistics using diffusion tensor imaging data from 184 participants to examine whole-brain differences in white matter microstructure between cluster analytically derived neurocognitive profiles, as well as unitary neurocognitive measures. Correlations between frontal gray and white matter were also examined.
Cluster 3 showed increased diffusion in predominately bilateral frontal and interhemisphere tracts (vs. Clusters 1 and 2), with relatively greater diffusion in the left hemisphere (vs. Cluster 1). Differences in radial diffusivity were more prominent compared with axial diffusivity. A weak association between regional frontal fractional anisotropy and previously defined abnormalities in gyrification was observed.
In a socially marginalized sample, we established several patterns in the covariation of white matter diffusion and neurocognitive functioning. These patterns elucidate the neurobiological substrates and vulnerabilities that are apt to underlie functional impairments inherent to this complex and heterogeneous population.
我们研究了与边缘人群中并存的躯体和精神疾病的多种神经认知特征相关的脑白质差异，这些人来自一个大型队列。我们先前的工作确定了三个特征聚类组：高功能组（第 1 组）、决策能力相对较强的低功能组（第 3 组）和决策能力相对较弱的中间组（第 2 组）。本研究扩展了先前研究中这些组之间皮质灰质差异的发现，并提供了低认知功能组（即第 3 组）存在潜在神经发育异常的证据。我们假设，改变的脑白质扩散将与认知功能最低的神经认知特征相关，并与先前观察到的灰质差异相关。
来自加拿大温哥华一个社会贫困社区的参与者接受了神经认知评估和神经影像学检查。我们使用来自 184 名参与者的弥散张量成像数据进行基于束流的空间统计学分析，以检查聚类分析得出的神经认知特征之间以及单一神经认知测量之间的全脑白质微观结构差异。还检查了额皮质和白质之间的相关性。
第 3 组显示出双侧额部和半球间束流的扩散增加（与第 1 组和第 2 组相比），且左侧半球的扩散相对更大（与第 1 组相比）。与轴向扩散相比，径向扩散差异更为明显。区域额部各向异性分数与先前定义的脑回异常之间存在微弱的相关性。
在一个社会边缘化的样本中，我们确定了白质扩散和神经认知功能之间的几种变化模式。这些模式阐明了易受功能障碍影响的神经生物学基础和脆弱性，而这些功能障碍是这一复杂和异质人群所固有的。
