The global burden of early life adversity (ELA) is profound. The World Health Organization has estimated that ELA accounts for almost 30% of all psychiatric cases. Yet, our ability to identify which individuals exposed to ELA will develop mental illness remains poor and there is a critical need to identify underlying pathways and mechanisms. This review proposes unpredictability as an understudied aspect of ELA that is tractable and presents a conceptual model that includes biologically plausible mechanistic pathways by which unpredictability impacts the developing brain. The model is supported by a synthesis of published and new data illustrating the significant impacts of patterns of signals on child development. We begin with an overview of the existing unpredictability literature, which has focused primarily on longer patterns of unpredictability (e.g. years, months, and days). We then describe our work testing the impact of patterns of parental signals on a moment-to-moment timescale, providing evidence that patterns of these signals during sensitive windows of development influence neurocircuit formation across species and thus may be an evolutionarily conserved process that shapes the developing brain. Next, attention is drawn to emerging themes which provide a framework for future directions of research including the evaluation of functions, such as effortful control, that may be particularly vulnerable to unpredictability, sensitive periods, sex differences, cross-cultural investigations, addressing causality, and unpredictability as a pathway by which other forms of ELA impact development. Finally, we provide suggestions for prevention and intervention, including the introduction of a screening instrument for the identification of children exposed to unpredictable experiences.

中文翻译：

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年度研究回顾：可预测性的力量——生命早期的信号模式塑造神经发育和心理健康轨迹

早年逆境（ELA）给全球带来了深远的负担。世界卫生组织估计，ELA 几乎占所有精神病病例的 30%。然而，我们识别哪些接触 ELA 的人会患上精神疾病的能力仍然很差，因此迫切需要确定潜在的途径和机制。这篇综述提出不可预测性是 ELA 的一个尚未得到充分研究的方面，它是易于处理的，并提出了一个概念模型，其中包括不可预测性影响发育中的大脑的生物学上合理的机制途径。该模型得到了已发表数据和新数据的综合支持，这些数据说明了信号模式对儿童发展的重大影响。我们首先概述现有的不可预测性文献，这些文献主要关注较长的不可预测性模式（例如年、月和日）。然后，我们描述了我们的工作，测试了父母信号模式对每时每刻时间尺度的影响，提供了证据表明这些信号在敏感发育窗口期间的模式影响跨物种的神经回路形成，因此可能是一个进化上保守的过程，塑造了正在发育的大脑。接下来，人们关注新兴主题，这些主题为未来的研究方向提供了框架，包括评估功能，例如努力控制，这些功能可能特别容易受到不可预测性、敏感时期、性别差异、跨文化调查、解决因果关系、不可预测性是其他形式的 ELA 影响发展的途径。最后，我们提供了预防和干预的建议，包括引入筛查工具来识别暴露于不可预测经历的儿童。