Decades of neuroimaging studies have shown modest differences in brain structure and connectivity in depression, hindering mechanistic insights or the identification of risk factors for disease onset¹. Furthermore, whereas depression is episodic, few longitudinal neuroimaging studies exist, limiting understanding of mechanisms that drive mood-state transitions. The emerging field of precision functional mapping has used densely sampled longitudinal neuroimaging data to show behaviourally meaningful differences in brain network topography and connectivity between and in healthy individuals^2,3,4, but this approach has not been applied in depression. Here, using precision functional mapping and several samples of deeply sampled individuals, we found that the frontostriatal salience network is expanded nearly twofold in the cortex of most individuals with depression. This effect was replicable in several samples and caused primarily by network border shifts, with three distinct modes of encroachment occurring in different individuals. Salience network expansion was stable over time, unaffected by mood state and detectable in children before the onset of depression later in adolescence. Longitudinal analyses of individuals scanned up to 62 times over 1.5 years identified connectivity changes in frontostriatal circuits that tracked fluctuations in specific symptoms and predicted future anhedonia symptoms. Together, these findings identify a trait-like brain network topology that may confer risk for depression and mood-state-dependent connectivity changes in frontostriatal circuits that predict the emergence and remission of depressive symptoms over time.

数十年的神经影像学研究表明，抑郁症患者的大脑结构和连接性存在适度差异，阻碍了机制见解或确定疾病发作的危险因素¹。此外，虽然抑郁症是发作性的，但很少有纵向神经影像学研究存在，这限制了对驱动情绪状态转变机制的理解。新兴的精确功能标测领域使用密集采样的纵向神经影像学数据来显示健康个体之间和健康个体之间大脑网络地形和连接性的行为意义差异^2,3,4，但这种方法尚未应用于抑郁症。在这里，使用精确的功能映射和几个深度采样个体的样本，我们发现大多数抑郁症患者的皮层中额纹状体显著性网络扩大了近两倍。这种效应在几个样本中是可复制的，主要由网络边界偏移引起，三种不同的侵占模式发生在不同的个体中。显著性网络扩展随着时间的推移是稳定的，不受情绪状态的影响，并且在青春期后期抑郁发作前可以在儿童中检测到。对在 1.5 年内扫描多达 62 次的个体进行纵向分析，确定了额纹状体回路的连接变化，这些变化跟踪了特定症状的波动并预测了未来的快感缺乏症状。总之，这些发现确定了一种类似特质的脑网络拓扑结构，该拓扑结构可能会赋予抑郁风险和额纹状体回路中的情绪状态依赖性连接变化，从而预测抑郁症状随时间的出现和缓解。