The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Laboratory for Neuroinformation, University of Electronic Science and Technology of China,Chengdu 610054,P.R. China.
Psychol Med. 2019 Apr;49(5):852-860. doi: 10.1017/S0033291718001502. Epub 2018 Jun 18.
Major depressive disorder (MDD) is associated with high risk of suicide. Conventional neuroimaging works showed abnormalities of static brain activity and connectivity in MDD with suicidal ideation (SI). However, little is known regarding alterations of brain dynamics. More broadly, it remains unclear whether temporal dynamics of the brain activity could predict the prognosis of SI.
We included MDD patients (n = 48) with and without SI and age-, gender-, and education-matched healthy controls (n = 30) who underwent resting-state functional magnetic resonance imaging. We first assessed dynamic amplitude of low-frequency fluctuation (dALFF) - a proxy for intrinsic brain activity (iBA) - using sliding-window analysis. Furthermore, the temporal variability (dynamics) of iBA was quantified as the variance of dALFF over time. In addition, the prediction of the severity of SI from temporal variability was conducted using a general linear model.
Compared with MDD without SI, the SI group showed decreased brain dynamics (less temporal variability) in the dorsal anterior cingulate cortex, the left orbital frontal cortex, the left inferior temporal gyrus, and the left hippocampus. Importantly, these temporal variabilities could be used to predict the severity of SI (r = 0.43, p = 0.03), whereas static ALFF could not in the current data set.
These findings suggest that alterations of temporal variability in regions involved in executive and emotional processing are associated with SI in MDD patients. This novel predictive model using the dynamics of iBA could be useful in developing neuromarkers for clinical applications.
重度抑郁症（MDD）与自杀风险高有关。传统的神经影像学研究表明，有自杀意念（SI）的 MDD 患者存在静息态脑活动和连接的异常。然而，关于脑动力学的改变知之甚少。更广泛地说，目前尚不清楚大脑活动的时间动力学是否可以预测 SI 的预后。
我们纳入了 48 名有和无 SI 的 MDD 患者（n=48）和年龄、性别、教育程度相匹配的 30 名健康对照者（n=30），并对他们进行了静息态功能磁共振成像。我们首先使用滑动窗口分析评估低频波动的动态幅度（dALFF）——内在脑活动（iBA）的替代指标。此外，通过时间上的方差来量化 iBA 的时间变异性（动态性）。此外，还使用广义线性模型从时间变异性来预测 SI 的严重程度。
与无 SI 的 MDD 患者相比，SI 组在背侧前扣带皮层、左侧眶额皮层、左侧颞下回和左侧海马体中表现出脑活动的减少（即时间变异性较低）。重要的是，这些时间变异性可以用于预测 SI 的严重程度（r=0.43，p=0.03），而在当前数据集中，静态 ALFF 则不能。
这些发现表明，参与执行和情绪处理的区域的时间变异性的改变与 MDD 患者的 SI 有关。这种使用 iBA 动力学的新的预测模型在开发用于临床应用的神经标记物方面可能是有用的。
