Principal Investigator:  Carol Ryff, Ph.D.; Co-Investigator, Richard P. Sloan, Ph.D.

 Midlife in the United States (MIDUS) is a national sample of continental U.S. residents, aged 25 to 74, who were first interviewed in 1995-1996. 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. The sample included more than 7,000 individuals on whom extensive psychosocial assessments (e.g., personality traits, wellbeing, affect, sense of control, quality of social relationships) were obtained. Such constructs received extensive attention in prior studies of adult development and aging, but the prior work was based on small, select samples with limited generalizability to the larger population. Including comprehensive psychosocial content in MIDUS afforded new directions for demography, epidemiology, and sociology by allowing linkage of diverse “individual difference” variables to core demographic factors and broad-ranging assessments of health. With support from the National Institute on Aging, a longitudinal follow up of the MIDUS sample was launched in 2004-2005 and an third was of begun in 2016. 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 biomedically oriented research. The research was not disease specific, given that psychosocial factors have relevance across multiple diseases. The broad aim was to “delineate the biopsychosocial pathways through which converging processes contribute to diverse health outcomes”. A further guiding theme was to investigate protective roles that behavioral and psychosocial factors have in delaying the onset of morbidity and mortality or in fostering resilience and recovery from health challenges once they occur. Comprehensive bioindicators and health assessments data were collected on a sample of 1,255 adults. Here, we describe the data-collection protocol, the specific biological measures and physical health assessments, and sociodemographic characteristics of the sample. As MIDUS data are in the public domain (see Inter-University Consortium for Political and Social Research), with more than 400 publications generated by scientists from diverse fields to date, numerous research opportunities accompany the new bioindicators. To facilitate understanding of these prospects, the five projects that comprise the MIDUS II data collection are described briefly below, followed by an overview of the major systems covered in the biological protocol.

Marna Freed