Midlife in the United States (MIDUS 2): Biomarker Project, 2004-2009

The Biomarker study is Project 4 of the Midlife in the United States (MIDUS) longitudinal study, a national survey of more than 7,000 Americans (aged 25 to 74) begun in 1994. The purpose of the larger study was to investigate the role of behavioral, psychological, and social factors in understanding age-related differences in physical and mental health. With support from the National Institute on Aging (NIA), a longitudinal follow-up of the original MIDUS samples [core sample (N = 3,487), metropolitan over-samples (N = 757), twins (N = 957 pairs), and siblings (N = 950)] was conducted in 2004-2006. Guiding hypotheses, at the most general level, were that behavioral and psychosocial factors are consequential for health (physical and mental). A description of the study and findings from it are available on the MIDUS website. The Biomarker Project (Project 4) of MIDUS 2 contains data from 1,255 respondents. These respondents include two distinct subsamples, all of whom completed the Project 1 Survey: (1) longitudinal survey sample (n = 1,054) and (2) Milwaukee sample (n = 201). The Milwaukee group contained individuals who participated in the baseline MIDUS Milwaukee study, initiated in 2005. The purpose of the Biomarker Project (Project 4) was to add comprehensive biological assessments on a subsample of MIDUS respondents, thus facilitating analyses that integrate behavioral and psychosocial factors with biology. The broad aim is to identify biopsychosocial pathways that contribute to diverse health outcomes. A further theme is to investigate protective roles that behavioral and psychosocial factors have in delaying morbidity and mortality, or in fostering resilience and recovery from health challenges once they occur. The research was not disease-specific, given that psychosocial factors have relevance across multiple health endpoints. Biomarker data collection was carried out at three General Clinical Research Centers (at UCLA, University of Wisconsin, and Georgetown University). The biomarkers reflect functioning of the hypothalamic-pituitary-adrenal axis, the autonomic nervous system, the immune system, cardiovascular system, musculoskeletal system, antioxidants, and metabolic processes. Our specimens (fasting blood draw, 12-hour urine, saliva) allow for assessment of multiple indicators within these major systems. The protocol also included assessments by clinicians or trained staff, including vital signs, morphology, functional capacities, bone densitometry, medication usage, and a physical exam. Project staff obtained indicators of heart-rate variability, beat to beat blood pressure, respiration, and salivary cortisol assessments during an experimental protocol that included both a cognitive and orthostatic challenge. Finally, to augment the self-reported data collected in Project 1, participants completed a medical history, self-administered questionnaire, and self-reported sleep assessments. For respondents at one site (UW-Madison), objective sleep assessments were also obtained with an Actiwatch(R) activity monitor.

生物标志物研究是美国中年纵向研究（MIDUS）的第4个项目，该研究始于1994年，是一项针对7000多名美国成年人（年龄在25至74岁之间）的全国性调查。该研究的总体目标在于探究行为、心理和社会因素在理解与年龄相关的身体和心理健康差异中的作用。在国家老龄研究所（NIA）的支持下，对原始MIDUS样本（核心样本（N = 3,487）、都市地区过度样本（N = 757）、双胞胎（N = 957对）和兄弟姐妹（N = 950））进行了1994-2006年的纵向追踪研究。在最高层次上，研究假设行为和心理社会因素对健康（身体和心理）具有决定性影响。关于该研究和其发现的信息可在MIDUS网站上查阅。MIDUS 2的生物标志物项目（第4个项目）包含了1,255名受访者的数据。这些受访者包括两个不同的子样本，他们均完成了第1个项目的调查：（1）纵向调查样本（n = 1,054）和（2）密尔沃基样本（n = 201）。密尔沃基组包含那些自2005年起参与MIDUS密尔沃基基准研究的个体。生物标志物项目（第4个项目）的目的是对MIDUS受访者的一部分进行全面的生物评估，从而促进将行为和心理社会因素与生物学因素相结合的分析。其广泛目标是识别有助于多种健康结果的生物心理社会途径。另一个研究主题是探究行为和心理社会因素在延缓发病率、死亡率，或是在健康挑战发生后的恢复和适应中发挥的保护作用。鉴于心理社会因素对多个健康终点具有相关性，本研究并非针对特定疾病。生物标志物数据收集在三个综合临床研究中心（加州大学洛杉矶分校、威斯康星大学和乔治城大学）进行。生物标志物反映了下丘脑-垂体-肾上腺轴、自主神经系统、免疫系统、心血管系统、骨骼肌肉系统、抗氧化剂和代谢过程的功能。我们的样本（空腹血液抽取、12小时尿液、唾液）允许对这些主要系统内的多个指标进行评估。研究方案还包括临床医生或培训有素的员工进行的评估，包括生命体征、形态学、功能能力、骨密度测量、药物使用和体格检查。项目工作人员在包含认知和直立性挑战的实验方案中获得了心率变异性、每次心跳血压、呼吸和唾液皮质醇评估的指标。最后，为了补充第1个项目中收集的自我报告数据，参与者完成了病史、自我管理的问卷和自我报告的睡眠评估。对于位于一个站点（威斯康星大学麦迪逊分校）的受访者，还使用了Actiwatch®活动监测器进行了客观的睡眠评估。