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# Wildfire smoke PM2.5 is associated with higher dementia incidence in older US adults
- URL: https://www.coios.me/wildfire-smoke-pm2-5-is-associated-with-higher-dementia/
- Published: 2026-10-12T13:22:08.000Z
- Updated: 2026-10-12T23:22:09.000Z
- Description: Each microgram per cubic metre of wildfire smoke PM2.5 was associated with a 2.9% increase in the incidence rate of dementia among 39.7 million US Medicare beneficiaries followed to 2019.
- Author: Daniel Ryan
- Tags: Tomorrow's world, A changing climate, Dementia, United States, #preprint, #refines, #item, #source-2026-10

A retrospective cohort of 39.7 million fee-for-service Medicare beneficiaries was followed from 2005 to 2019 for incident Alzheimer's disease and all-cause dementia. Annual high-resolution estimates of smoke and non-smoke PM2.5 were assigned and fitted in stratified Cox models. Per microgram per cubic metre, smoke PM2.5 was associated with incident Alzheimer's disease (HR 1.015) and with all dementia (1.029). The association was stronger for the smoke carbonaceous fraction, at 1.090 for all dementia. The authors attribute 11,142 dementia cases a year to smoke PM2.5, although exposure was modelled rather than measured.

*Why it is interesting: The study separates wildfire smoke from background PM2.5 and resolves the dementia association to its carbonaceous fraction. Smoke carried the higher hazard per unit mass but the lower per interquartile range, which bears on wildfire-smoke health-impact assessments.*

Source

[medRxiv, 11 October 2026](https://doi.org/10.64898/2026.10.08.26364863?ref=coios.me)

Paper

Carbonaceous Components Underlying Wildfire Smoke PM 2.5 -Associated Alzheimer's Disease and Related Dementias in Older US Adults

Authors

Jin Z, Xu K, Qi M, Zhu Q, Yang B, Ferrada GA et al.

DOI

10.64898/2026.10.08.26364863

Type

Preprint

Design

Retrospective cohort of 39,678,630 fee-for-service Medicare beneficiaries, followed 2005-2019, linked to annual high-resolution smoke and non-smoke PM2.5 and carbon components; stratified Cox models

Verdict

Refines prior evidence

Driver

[A changing climate](https://www.coios.me/d-climate/)

Driver

[Dementia](https://www.coios.me/d-dementia/)