Stress effects on childhood brain development

描述（由申请人提供）：本研究的目的是探讨压力对儿童大脑发育的影响。虽然发育期间的低压力水平可以促进以后生活中的健康应对，但长期压力会导致精神疾病和认知能力受损。虽然慢性应激不能在人类实验中被操纵，但有可能研究自然发生的应激暴露变化的影响。儿童社会经济地位（SES）是一个由父母教育、职业和收入组成的指数，它与压力暴露和压力反应的梯度有关。较低的社会经济地位与更多的压力生活事件和更大的压力生理失调有关。此外，低社会地位环境与较少的缓冲压力影响的因素有关。最近的动物研究提供了证据，表明压力可能会加速重要的成熟过程。这是有问题的，因为在人类身上发现，较慢的大脑发育与较好的认知能力有关。我提议测试压力加速幼儿大脑发育的新假设。此外，我将探讨大脑早期成熟是否是对高压力环境的适应性反应。为了验证这些假设，我将招募经历过许多压力生活事件的低经济地位背景的6岁儿童（高压力组，N=40）和经历过很少压力生活事件的高经济地位背景的儿童（低压力组，N=40）。我将1)描述高压力组和低压力组在感知压力、生理压力标记和认知表现方面的差异；2)测试高应激组是否表现出更高的脑结构成熟度（以更大的皮质厚度和更大的白质定向扩散率为指标）；3)探讨结构成熟度差异是否反映在功能网络中；4)探讨高应激组的早熟是否与认知能力和心理健康的优劣相关。在高压力

DESCRIPTION (provided by applicant): The goal of this research is to investigate the effects of stress on childhood brain development. While low levels of stress during development can promote healthy coping later in life, chronic stress sets up vulnerabilities for psychiatric disorders and impairs cognition. Although chronic stress cannot be experimentally manipulated in humans, it is possible to investigate the effects of naturally occurring variations in stress exposure. Childhood socioeconomic status (SES), an index composed of parental education, occupation, and income, is linked to a gradient in exposure and reactivity to stress. Lower SES is associated with more stressful life events and greater dysregulation of stress physiology. Further, low SES environments are associated with fewer factors that buffer the effects of stress. Recent animal research has provided evidence that stress might accelerate important maturational processes. This is problematic in light of the finding in humans that slower brain development is associated with superior cognitive skills. I propose to test the novel hypothesis that stress accelerates brain development in young children. Further, I will explore the question of whether early brain maturation is an adaptive response to a high-stress environment. To test these hypotheses, I will recruit six-year-old children from low SES backgrounds who have experience many stressful life events (high-stress group, N=40), and children from high SES backgrounds who have experienced few stressful life events (low-stress group, N=40). I will 1) characterize differences in perceived stress, physiological stress markers, and cognitive performance between high- and low-stress groups; 2) test whether the high-stress group exhibits greater structural brain maturity as indexed by greater cortical thickness and more directional diffusivity in white matter; 3) explore whether structural maturation differences are reflected in functional networks; and 4) investigate whether early maturation in the high-stress group is associated with inferior or superior cognitive abilities and mental health. In high-stress environments, accelerated maturation may be adaptive because it protects networks supporting cognitive skills in a partially developed state, rendering them less vulnerable to environmental insult. In sum, this research will be the first to test the innovative hypothesis that stress accelerates brain development in young children, and to explore whether accelerated development is an adaptive response to stress. Results of this study will help fill a major gap in knowledge that has evolved from the underrepresentation of children from low SES backgrounds in cognitive neuroscience research. Our findings will elucidate the neurodevelopmental mechanisms by which childhood stress impacts cognition and increases risk for psychiatric illness. Knowledge gained from this work will provide insight into whether interventions should aim to accelerate or decelerate brain maturation in children exposed to stress.