Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada.
Physiol Behav. 2012 Apr 12;106(1):65-72. doi: 10.1016/j.physbeh.2011.10.003. Epub 2011 Oct 12.
Different factors have been associated with changes in the regulation of the two major stress response systems of the human body, the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal (HPA) axis. Changes in these systems have been associated with various (psycho)pathologies across adulthood, and are thus frequently assessed within the context of allostatic load. Early Life Adversity (ELA) has been identified as one such factor. Individuals with histories of ELA show evidence of elevated basal and reactive salivary alpha amylase (sAA) levels (a marker of SNS activity), blunted cortisol levels (a marker of HPA axis activity), and an asymmetrical relationship between the two variables. However, variable methods used in the past to measure each variable, and the relationship between the two systems, prevent us from drawing firm conclusions. This preliminary study investigated whether the ratio of reactive sAA over reactive cortisol would be more informative to investigate the relationship between the two stress systems than the ratio of cortisol over sAA, or either marker alone, and whether there is a systematic link between this marker and subjective indexes of chronic stress and depression. We studied this in a total of 37 subjects (n=20 with signs of early life adversity and n=17 without) exposed to the Trier social stress test. Using a specific formula to determine the ratio of sAA over cortisol, we found a systematically stronger positive relationship with indexes of chronic stress and depression when compared to cortisol over sAA, or either marker alone. Our findings suggest that the ratio of sAA over cortisol might be a better marker of stress systems dysregulation than the ratio of cortisol over sAA, sAA or cortisol alone. The usefulness of this marker for other chronic stress states as found in allostatic load is discussed.
不同的因素与人体两大主要应激反应系统——交感神经系统（SNS）和下丘脑-垂体-肾上腺（HPA）轴的调节变化有关。这些系统的变化与成年期的各种（心理）病理学有关，因此经常在适应负荷的背景下进行评估。早期生活逆境（ELA）就是这样一个因素。有 ELA 病史的个体表现出基础和反应性唾液α淀粉酶（SAA）水平升高（SNS 活性的标志物）、皮质醇水平降低（HPA 轴活性的标志物）以及这两个变量之间的不对称关系的证据。然而，过去用于测量每个变量的方法以及两个系统之间的关系存在差异，这使得我们无法得出确定的结论。这项初步研究调查了反应性 SAA 与反应性皮质醇的比值是否比皮质醇与 SAA 的比值或单独的任何一个标志物更能说明两个应激系统之间的关系，以及该标志物与慢性应激和抑郁的主观指标之间是否存在系统联系。我们在总共 37 名受试者（有早期生活逆境迹象的 n=20 名，无早期生活逆境迹象的 n=17 名）中研究了这一问题，他们接受了特里尔社会应激测试。使用特定的公式来确定 SAA 与皮质醇的比值，我们发现与慢性应激和抑郁的指标相比，该比值与皮质醇与 SAA 的比值或单独的任何一个标志物都有更强的正相关关系。我们的研究结果表明，与皮质醇与 SAA 的比值相比，SAA 与皮质醇的比值可能是应激系统失调的更好标志物，而不是皮质醇与 SAA 的比值、SAA 或皮质醇单独的比值。我们还讨论了该标志物在适应负荷中发现的其他慢性应激状态下的有用性。
