{ "abstract": "The prevalence of functional impairment (i.e., difficulty performing daily activities such as bathing and dressing) has increased among middle-aged Americans, but longitudinal data are lacking. The objective of this study was to examine trajectories of functional status and incidence of functional impairment among middle-aged adults across 4 birth cohorts. We conducted a cohort study of 14,707 participants ages 50–56 enrolled between 1992–2010 in the nationally representative Health and Retirement Study (HRS) who were independent at baseline in self- or proxy-reported basic activities of daily living (ADLs, score 0–6) and instrumental ADLs (IADLs, score 0–5). Participants were born in one of four birth cohorts: “Pre-War Babies,” 1935–1941; “War Babies,” 1942–1947; “Early Baby Boomers,” 1948–1953; or “Mid Baby Boomers,” 1954–1959. Primary outcomes were trajectories of functional status (number of ADL and IADL difficulties) and incidence of functional impairment (difficulty with ≥1 ADLs or ≥1 IADLs) before age 65. We used group-based trajectory models to identify distinct classes of ADL change and multinomial logistic regression models to examine association of birth cohort with group membership. From the earliest to latest birth cohort, the percentages excluded at baseline due to prevalent functional impairment were 13.8%, 9.9%, 9.6%, and 11.7%. Mean age among participants was 53.2 years, 51.6% were women, 9.9% identified as Black, and 8.0% as Latino. In adjusted and unadjusted analyses, Pre-War Babies and War Babies were at significantly higher risk of belonging to trajectory groups with higher levels of impairment versus Mid Boomers. Over a median follow-up of 7.6 years, average annual incidence rates for ADL impairment from earliest to latest cohort were 2.0%, 0.7%, 0.7%, and 1.0%. Findings were similar for IADLs. Functional trajectories and incidence of functional impairment improved from earlier to later birth cohorts. Findings suggest differing risk factors for mid-life prevalent versus incident functional impairment.", "abstract_shown": true, "affiliations": [ "Division of Geriatric Medicine, Department of Medicine, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America", "Leonard Davis Institute of Health Economics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America", "Geriatrics and Extended Care Program, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, Pennsylvania, United States of America", "Center for Health Evaluation Research and Promotion, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, Pennsylvania, United States of America", "Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America", "Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, Michigan, United States of America", "Division of General Internal Medicine, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America", "Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America" ], "article_type": "Research Article", "arxiv": null, "author_total": 8, "authors": [ { "affs": [ 0 ], "name": "Rebecca T. Brown" }, { "affs": [ 1 ], "name": "Xi Zuo" }, { "affs": [ 2 ], "name": "Haotian Zheng" }, { "affs": [ 3 ], "name": "Kira L. Ryskina" }, { "affs": [ 4 ], "name": "Anne R. Cappola" }, { "affs": [ 5 ], "name": "Irma Elo" }, { "affs": [ 6 ], "name": "Norma B. Coe" }, { "affs": [ 7 ], "name": "Dawei Xie" } ], "bibtex": "https://research.draconitic.com/paper/dpx0tbq374mya.bib", "cited_by": 0, "doi": "10.1371/journal.pone.0358337", "fulltext_url": null, "id": "dpx0tbq374mya", "issns": [ "1932-6203" ], "landing_url": "https://doi.org/10.1371/journal.pone.0358337", "language": null, "licence": "CC-BY-4.0", "licence_label": "CC BY 4.0", "licence_source": "journal", "licence_url": "https://creativecommons.org/licenses/by/4.0/", "metadata_licence": null, "native_subjects": [ [ "openalex", "2739|Aging, Health, and Disability" ], [ "plos", "/Biology and life sciences/Neuroscience/Cognitive neuroscience/Cognitive neurology/Cognitive impairment" ], [ "plos", "/Biology and life sciences/Neuroscience/Cognitive science/Cognitive neuroscience/Cognitive neurology/Cognitive impairment" ], [ "plos", "/Biology and life sciences/Physiology/Physiological parameters/Body weight" ], [ "plos", "/Medicine and health sciences/Epidemiology" ], [ "plos", "/Medicine and health sciences/Epidemiology/Medical risk factors" ], [ "plos", "/Medicine and health sciences/Health care/Quality of life/Activities of daily living" ], [ "plos", "/Medicine and health sciences/Health care/Socioeconomic aspects of health" ], [ "plos", "/Medicine and health sciences/Neurology/Cognitive neurology/Cognitive impairment" ], [ "plos", "/Medicine and health sciences/Public and occupational health/Socioeconomic aspects of health" ], [ "plos", "/Research and analysis methods/Research design/Cohort studies" ], [ "plos", "/Social sciences/Sociology/Education/Schools" ] ], "openalex": "W7213543654", "pdf_url": "https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0358337&type=printable", "pmcid": null, "pmid": null, "published": "2026-09-18", "publisher": "Public Library of Science", "ris": "https://research.draconitic.com/paper/dpx0tbq374mya.ris", "sources": [ { "first_seen": "2026-10-30T12:17:49Z", "native_id": "10.1371/journal.pone.0358337", "source": "plos", "url": "https://doi.org/10.1371/journal.pone.0358337" } ], "subjects": [ { "field": "biology", "origin": "plos:cognitive neuroscience", "subfield": "neuroscience" }, { "field": "medicine", "origin": "plos:epidemiology", "subfield": "epidemiology-public-health" } ], "title": "Trends in trajectories and incidence of functional impairment in middle-aged Americans", "title_text": "Trends in trajectories and incidence of functional impairment in middle-aged Americans", "type": "peer-reviewed", "updated_at": "2026-10-30T12:17:49Z", "url": "https://research.draconitic.com/paper/dpx0tbq374mya", "venue": "PLOS One", "versions": [] }