{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"medRxiv"}],"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T21:19:37Z","timestamp":1792790377904,"version":"4.5.0"},"posted":{"date-parts":[[2026,10,11]]},"group-title":"Epidemiology","reference-count":54,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,10,11]],"date-time":"2026-10-11T00:00:00Z","timestamp":1791676800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"name":"National Institutes of Health","award":["R01ES034175"],"award-info":[{"award-number":["R01ES034175"]}]},{"name":"U.S. Department of Energy","id":[{"id":"https:\/\/ror.org\/01bj3aw27","id-type":"ROR","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,10,11]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>\n                  Wildfire smoke exposure is increasing across the U.S., but the long-term neurological effects of smoke-specific fine particulate matter (PM\n                  <jats:sub>2.5<\/jats:sub>\n                  ) and its carbonaceous components remain uncertain. Using Medicare data from 2002 through 2019, we examined incident Alzheimer\u2019s disease (AD) and Alzheimer\u2019s disease and related dementias (ADRD) among 39,678,630 fee-for-service Medicare beneficiaries followed from 2005 through 2019. We identified 3,501,414 incident AD cases over 258.5 million person-years and 8,377,416 incident ADRD cases over 248.6 million person-years. We linked the cohort with annual, high-resolution estimates of smoke and non-smoke PM\n                  <jats:sub>2.5<\/jats:sub>\n                  mass and carbonaceous components (elemental and organic carbon) and fitted stratified Cox proportional hazards models. Per 1 \u00b5g\/m\n                  <jats:sup>3<\/jats:sup>\n                  increase, smoke PM\n                  <jats:sub>2.5<\/jats:sub>\n                  was associated with incident AD (hazard ratio [HR], 1.015, 95% confidence interval [CI], 1.005-1.026) and ADRD (1.029 [1.024-1.035]). Smoke carbonaceous fraction was also associated with AD (1.063 [1.042-1.085]) and ADRD (1.090 [1.077-1.103]). Within the ADRD endpoint, smoke-related associations exceeded their corresponding non-smoke associations on a per-unit-mass basis. Per interquartile range, associations were smaller for smoke PM\n                  <jats:sub>2.5<\/jats:sub>\n                  (AD, 1.005 [1.002-1.008]; ADRD, 1.009 [1.008-1.011]) than for non-smoke PM\n                  <jats:sub>2.5<\/jats:sub>\n                  (AD, 1.086 [1.079-1.094]; ADRD, 1.048 [1.043-1.053]). Associations varied across geographic, racial, socioeconomic, and clinical subgroups. Long-term wildfire smoke exposure, particularly its carbonaceous fraction, was associated with higher incidence of AD and ADRD among older U.S. adults. The associations correspond to 2,284 and 11,142 incident cases per year of AD and ADRD attributable to smoke PM\n                  <jats:sub>2.5<\/jats:sub>\n                  among older Medicare beneficiaries, with the carbonaceous fraction accounting for most of this burden. These findings support the use of source-resolved and composition-specific smoke metrics in dementia research and wildfire-smoke health-impact assessments.\n                <\/jats:p>","DOI":"10.64898\/2026.10.08.26364863","type":"posted-content","created":{"date-parts":[[2026,10,11]],"date-time":"2026-10-11T15:10:23Z","timestamp":1791731423000},"source":"Crossref","is-referenced-by-count":0,"title":["Carbonaceous Components Underlying Wildfire Smoke PM\n                  <sub>2.5<\/sub>\n                  -Associated Alzheimer\u2019s Disease and Related Dementias in Older US Adults"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3510-4339","authenticated-orcid":false,"given":"Zhihao","family":"Jin","sequence":"first","affiliation":[{"name":"Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ke","family":"Xu","sequence":"additional","affiliation":[{"name":"Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Meng","family":"Qi","sequence":"additional","affiliation":[{"name":"Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qiao","family":"Zhu","sequence":"additional","affiliation":[{"name":"Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Binyu","family":"Yang","sequence":"additional","affiliation":[{"name":"Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gonzalo A.","family":"Ferrada","sequence":"additional","affiliation":[{"name":"Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996, USA"},{"name":"Integrated Computational Earth Sciences Group, Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37381, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joshua S.","family":"Fu","sequence":"additional","affiliation":[{"name":"Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996, USA"},{"name":"Integrated Computational Earth Sciences Group, Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37381, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Noah","family":"Scovronick","sequence":"additional","affiliation":[{"name":"Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Howard H.","family":"Chang","sequence":"additional","affiliation":[{"name":"Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alvaro","family":"Alonso","sequence":"additional","affiliation":[{"name":"Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA"},{"name":"Department of Preventive Medicine and Public Health, School of Medicine, University of Navarra, 31008 Pamplona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kyle","family":"Steenland","sequence":"additional","affiliation":[{"name":"Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yang","family":"Liu","sequence":"additional","affiliation":[{"name":"Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026101504503018000_2026.10.08.26364863v1.1","doi-asserted-by":"crossref","first-page":"1208","DOI":"10.1038\/s41467-022-28835-2","article-title":"Spatial and temporal expansion of global wildland fire activity in response to climate change","volume":"13","year":"2022","journal-title":"Nature Communications"},{"key":"2026101504503018000_2026.10.08.26364863v1.2","doi-asserted-by":"publisher","DOI":"10.1021\/acs.est.5c01641"},{"key":"2026101504503018000_2026.10.08.26364863v1.3","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1617394114"},{"key":"2026101504503018000_2026.10.08.26364863v1.4","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1607171113"},{"key":"2026101504503018000_2026.10.08.26364863v1.5","doi-asserted-by":"crossref","unstructured":"Qiu, M. et al. 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