Background

Suicidal ideation (SI) is a common symptom of major depressive disorder (MDD). Accumulating studies demonstrated that MDD with SI was associated with static alterations in brain activity and functional connectivity. However, given that brain is a highly dynamic system, the changes of brain dynamic patterns in MDD with SI remain unknown.

Methods

We included 60 MDD patients with SI (MDD-SI), 58 MDD patients without SI (MDD-NSI), and 58 healthy controls (HCs) who underwent resting-state functional magnetic resonance imaging. The sliding-window approach was used to calculate the dynamic fractional amplitude of low-frequency fluctuation (dfALFF) and dynamic degree centrality (dDC) to characterize the temporal dynamic regional activity and distant functional connectivity. We compared dfALFF and dDC across groups and further conducted correlations between abnormal dynamic metrics and the severity of suicidality.

Results

In terms of the dynamic regional activity, MDD-SI showed decreased dfALFF in the left lingual gyrus and right middle occipital gyrus compared with MDD-NSI; in terms of the dynamic distant connectivity, MDD-SI showed decreased dDC in the right middle frontal gyrus compared with MDD-NSI. The decreased dDC in the right middle frontal gyrus was correlated with increased severity of suicidality.

Limitations

The relatively small sample size.

Conclusions

We demonstrate the specific brain dynamic patterns of MDD-SI in regional activity and distant functional connectivity compared to MDD-NSI. Especially the decreased temporal variability of the distant connectivity in the middle frontal gyrus was associated with SI. These altered dynamic patterns may represent a potential neurobiological diathesis of SI in MDD.

中文翻译：

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有自杀意念的重度抑郁症的脑动力学异常

背景

自杀意念 (SI) 是重度抑郁症 (MDD) 的常见症状。越来越多的研究表明，伴有 SI 的 MDD 与大脑活动和功能连接的静态改变有关。然而，鉴于大脑是一个高度动态的系统，MDD 与 SI 的大脑动态模式的变化仍然未知。

方法

我们纳入了 60 名患有 SI 的 MDD 患者 (MDD-SI)、58 名没有 SI 的 MDD 患者 (MDD-NSI) 和 58 名接受静息状态功能磁共振成像的健康对照 (HCs)。滑动窗口法用于计算低频波动的动态分数幅度（dfALFF）和动态度中心性（dDC），以表征时间动态区域活动和远距离功能连接。我们比较了各组的 dfALFF 和 dDC，并进一步分析了异常动态指标与自杀严重程度之间的相关性。

结果

在动态区域活动方面，MDD-SI与MDD-NSI相比，左侧舌回和右侧枕中回的dfALFF降低；在动态远距离连接方面，与 MDD-NSI 相比，MDD-SI 显示右侧额中回的 dDC 降低。右侧额中回的 dDC 下降与自杀严重程度的增加相关。

限制

样本量相对较小。

结论

与 MDD-NSI 相比，我们展示了 MDD-SI 在区域活动和远程功能连接中的特定大脑动态模式。尤其是额中回远距离连接的时间变异性降低与 SI 相关。这些改变的动态模式可能代表 MDD 中 SI 的潜在神经生物学素质。