Mid-Life in the U.S. Study (MIDUS)

http://www.midus.wisc.edu/

Overview
MIDUS (Midlife in the U.S.) is a national sample of continental U.S. residents, aged 25 to 74, who were first interviewed in 1995/96. The original study was conceived by a multidisciplinary team of investigators interested in the influence of psychological and social factors on health, broadly defined, as people age from early adulthood to later life. With support from the National Institute on Aging, a longitudinal follow-up of the MIDUS sample was launched in 2004/05. The objective was to investigate long-term change (9-10 years) across the sociodemographic, psychosocial, behavioral, and health domains assessed at baseline. A further objective was to extend the scientific scope of the study by adding comprehensive biological assessments on a subsample of respondents. In its longitudinal extension, MIDUS thus became a forum for investigating health as an integrative process, which involved combining the behavioral and social sciences together with bio-medically oriented research. Based on the quality and use of the MIDUS data, the study was extended for a 3rd round of funding (2011-2016), with the objective of expanding the MIDUS sample, known as the MIDUS Refresher. Both the MIDUS Refresher and MIDUS 3 will substantially augment the current battery of survey measures to include questions specific to the economic recession that began in 2008. This study is designed to allow researchers to examine questions about American’s health and well-being with sensitivity to the changing historical context.

Data Collection
The original sample of over 7,000 adults included: a national sample, obtained through random-digit dialing procedures (Main RDD); siblings of many respondents (N=950), for the purpose of investigating familial factors in health and well-being; and a national sample of twins (N=1,914), of the same age range as the national RDD sample (for the purpose of investigating genetic influences on health and well-being), and the over-samples in select metropolitan areas (N=757).

Participation in the national survey at Time 2 (MIDUS II) was an eligibility criterion for participation in additional projects within the MIDUS Program Project framework.  Many participants in the national survey completed more than one of these additional projects.  The daily diary assessments (Project 2) involved 8 days of phone assessments about multiple aspects of daily life, including stressful experiences at work and with family, and emotional reactions to them. Daily stress assessments were also obtained on a large subsample at MIDUS I and thus constitute longitudinal assessments for part of the Project 2 sample. For MIDUS II, the sample was expanded, and assessments of daily salivary cortisol were added to the protocol. Assessments of cognitive function (Project 3) were obtained by phone interviews. All participants in Project 1 were invited to participate in Project 3 cognitive assessments. The biological protocol (Project 4) consisted of the bioindicator and health assessments (see below). The neuroscience assessments (Project 5) were carried out on a subsample of the Project 4 respondents at one data collection site (University of Wisconsin-Madison). Assessments focused on affective reactivity and recovery and include multiple electroencephalography (EEG) and electromyography (EGM) indicators as well as structural magnetic resonance imaging (MRI) and task event-related functional imaging (fMRI) on a subgroup of respondents.

In 2013, a third wave (MIDUS III) of survey data was collected on longitudinal participants. Data collection for this follow-up wave largely repeated baseline assessments (e.g., phone interview and extensive self-administered questionnaire), with additional questions in selected areas (e.g., economic recession experiences, optimism and coping, stressful life events, and caregiving). A third wave of cognitive functioning data were also collected.

Beginning in 2012, the MIDUS received funding to continue data collection on a new sample of respondents called the MIDUS Refresher. Data collection began in 2012.

Biomarkers
All living Project 1 (national survey) respondents were considered eligible for participation if their existing health information indicated an ability to travel to the clinic without excessive risk to the respondent or project staff.  Siblings of main sample respondents were not part of the recruitment pool (primarily because of cost), but members of the twin sample were included.  Members of the Milwaukee sample of African Americans, newly recruited at MIDUS II, were also part of the recruitment pool.

Specimens (fasting blood draw, 12-hour urine, saliva) were collected to allow for assessment of major biological systems:  cardiovascular, neuroendocrine, inflammatory, musculoskeletal, and anti-oxidants. The Figure below outlines the specific measures/assays that were obtained for each major regulatory system. In addition, the Project 4 biological protocol included multiple assessments obtained by clinicians or trained staff, including vital signs, morphology, functional capacities, bone densitometry, medication usage, and a physical exam (details provided in Figure 1). We also 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 extensive self-reported data collected in Project 1 survey assessments, participants in the biological protocol (Project 4) completed a medical history and self-reported sleep assessments. For respondents at one site (UW-Madison), objective sleep assessments were also obtained with an Actiwatch® activity monitor.

Publications
http://www.midus.wisc.edu/findings/

Wiley, J. F., Gruenewald, T. L., Karlamangla, A. S., & Seeman, T. E. (2016). Modeling multisystem physiological dysregulation.
  Psychosomatic Medicine. Advance online publication.

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