Abstract

Allostatic load is the wear-and-tear organisms accumulate due to senescence and stress; it is measured by combining biomarkers from multiple somatic systems into allostatic load indices (ALIs). Frequently used in human research, ALIs have shown consistent results across samples despite different biomarkers and methods. However, determining optimal models likely is necessary if ALIs are to be feasible research tools in other species. Herein, we build on prior research in western lowland gorillas to explore one potential method for determining which biomarkers may be best for estimating allostatic load. After narrowing down which biomarkers to include using a combination of forward stepwise regression and independent biomarker associations with project variables, we estimated allostatic load using both the traditional one-tailed quartile method as well as a multi-method approach. There was a significant positive association between allostatic load and triglycerides, but not cholesterol, both of which are commonly used as diagnostic markers of poor health. Using binomial generalized linear models, a one-unit increase in allostatic load was associated with increased risk of all-cause morbidity and mortality, but reduced risk of cardiac disease. Although conclusions were similar, compared to our original ALIs, these new ALIs had weaker effect sizes and poorer relative goodness of fit, suggesting this method for identifying the best possible list of biomarkers to include in an index was not effective. This report continues the development of ALIs as a clinical tool in wildlife while systematically testing one possible method for determining an optimal ALI for a particular species.

摘要

异源负荷是由于衰老和压力而积累的磨损生物；它是通过将来自多个体细胞系统的生物标记物组合到同位负荷指数（ALIs）中进行测量的。尽管生物标志物和方法不同，但在人类研究中经常使用的ALI在所有样品中均显示出一致的结果。但是，如果要使ALI在其他物种中成为可行的研究工具，则可能需要确定最佳模型。在本文中，我们基于先前在西部低地大猩猩上的研究来探索一种潜在的方法，以确定哪种生物标记物可能最适合估计静力负荷。在通过结合逐步逐步回归和独立的生物标记与项目变量的组合来缩小要包括的生物标记后，我们使用传统的单尾四分位数方法以及多方法方法估计了静载荷。恒定负荷与甘油三酸酯之间存在显着的正相关，而胆固醇却没有，两者通常被用作不良健康的诊断标志。使用二项式广义线性模型，单位负荷增加一个单位会增加全因发病和死亡的风险，但会降低心脏病的风险。尽管结论相似，但与我们最初的ALI相比，这些新的ALI的效应大小较弱，而拟合的相对良好性较差，这表明这种用于识别可能包含在索引中的最佳生物标志物列表的方法无效。