{
  "abstract": "Background: Air pollution and built environment features are increasingly associated with negative health outcomes, yet their relation to brain health in cognitively healthy older adults remains unclear.\n\nMethods: To synthesise the extant literature, we conducted a systematic review, searching MEDLINE (PubMed) and Web of Science (Core Collection) from inception to February 23, 2026. Eligible studies assessed a natural or built environmental exposure against brain magnetic resonance imaging (MRI) measures in cognitively healthy older adults (ages 65+). Reviewers screened and extracted summary data from published reports in Covidence; no individual patient data were sought. The main outcome was brain health; findings were synthesised narratively using an effect-direction approach, as heterogeneous exposures, outcomes, and effect metrics precluded pooling.\n\nFindings: Of 2,496 records screened, 27 studies met eligibility, comprising >84,000 older adults across 10 countries: United States, South Korea, United Kingdom, France, Spain, Sweden, Netherlands, Taiwan, Germany, and Japan. Thirteen studies were cross-sectional and 14 were cohort studies (nine observational and five longitudinal). Higher air pollution exposure—particularly PM2.5, NO2, and PM10—was associated with altered brain structure: smaller total, grey matter, and white matter volumes, greater white matter hyperintensities, cortical thinning, and smaller medial temporal and hippocampal volumes; greenspace was associated with more favourable brain structure in several mostly cross-sectional studies, though findings were not uniform. Thirteen studies met criteria for high methodological quality and low though not uniform risk of bias; outcome assessment was a recurring source of bias (12 of 27 studies), and four of the five longitudinal studies did not meet criterion for follow-up adequacy.\n\nInterpretation: This review synthesises emerging observational evidence that air pollution is associated with differences in brain structure in cognitively healthy ageing. Because the included evidence is predominantly cross-sectional, these associations are hypothesis generating; if confirmed in longitudinal studies, this modifiable exposure could serve as a potential target for policymakers aiming to protect brain health in the fastest growing segment of the global population.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": null,
  "author_total": 3,
  "authors": [
    {
      "name": "Kelly E Perry"
    },
    {
      "name": "Breanna Marie Watterson"
    },
    {
      "name": "Jenna Louise Merenstein"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/6gnh6abrbzkhw.bib",
  "cited_by": 0,
  "doi": "10.31234/osf.io/yj7xw_v2",
  "fulltext_url": null,
  "id": "6gnh6abrbzkhw",
  "issns": [],
  "landing_url": "https://osf.io/preprints/psyarxiv/yj7xw_v2/",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "bepress",
      "Built Environments"
    ],
    [
      "bepress",
      "Environmental Psychology"
    ],
    [
      "bepress",
      "Natural Environments"
    ],
    [
      "bepress",
      "Neuroscience"
    ],
    [
      "bepress",
      "Social Settings"
    ],
    [
      "bepress",
      "Social and Behavioral Sciences"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://osf.io/yj7xw/download",
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-12",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/6gnh6abrbzkhw.ris",
  "sources": [
    {
      "first_seen": "2026-11-13T12:21:17Z",
      "native_id": "yj7xw",
      "source": "osf",
      "url": "https://osf.io/preprints/psyarxiv/yj7xw_v2/"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "bepress:Neuroscience",
      "subfield": "neuroscience"
    }
  ],
  "title": "Environmental Exposures and Brain Magnetic Resonance Imaging Phenotypes in Cognitively Healthy Ageing: A Systematic Review",
  "title_text": "Environmental Exposures and Brain Magnetic Resonance Imaging Phenotypes in Cognitively Healthy Ageing: A Systematic Review",
  "type": "preprint",
  "updated_at": "2026-11-13T12:21:17Z",
  "url": "https://research.draconitic.com/paper/6gnh6abrbzkhw",
  "venue": "PsyArXiv",
  "versions": []
}