The relationship between air pollution and dementia in mood disorders: The moderating role of sleep patterns—— A prospective study from the UK Biobank

Aug 8, 2025Journal of affective disorders

Air pollution and dementia risk in mood disorders may vary with sleep patterns: A UK Biobank study

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Abstract

Mood disorders significantly increased dementia risk with a hazard ratio of 5.69.

Increased exposure to particulate matter (PM) is associated with a higher risk of dementia, with a hazard ratio of 1.67 per 10 μg/m³.
Other pollutants such as PM2.5, PM10, nitrogen oxides (NO), and nitrogen dioxide (NO2) did not show significant associations with dementia risk after adjustment for covariates.
Five specific sleep behaviors, when scored as healthy (≥4), may reduce the negative impact of PM exposure on dementia risk.
Both the individual sleep behaviors and overall sleep pattern scores were found to mitigate the adverse effects of PM on dementia risk.

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PURPOSE: This study aims to quantify dementia risk in mood disorder patients, to examine the association between air pollution and dementia risk, and to assess whether sleep patterns incorporating five specific sleep behaviors modifies this relationship.

METHODS: This prospective cohort study enrolled 459,635 individuals from the UK Biobank, 46,256 mood disorder patients at baseline; of those, 1494 developed dementia during follow-up. Air pollution exposure (PM, PM, PM, NO, and NO) was estimated using land-use regression models. Sleep patterns were defined according to five sleep domains (sleep chronotype, duration, insomnia, snoring, and daytime sleepiness), with a score ≥ 4 considered healthy. Proportional hazards regression (Cox models) was employed to assess hazard ratios (HRs) for dementia risk. Stratification methodologies were performed to evaluate modification by both individual sleep behaviors and the total sleep pattern score on PM-dementia associations. 2.5 10C2X2.5

RESULTS: Mood disorders significantly increased dementia risk (HR: 5.69, 95 %CI: 5.36-6.04, P < 0.001). Notably, a significant association with increased dementia risk was observed only for PM(HR: 1.67 per 10 μg/m, 95 % CI: 1.04-2.69, P = 0.034), while PM, PM, NO, and NOshowed no significant associations after comprehensive covariate adjustment. Both five sleep domains and the sleep patterns were found to mitigate the adverse effect of PMon dementia risk. 2.5C10 2X2.5 3

CONCLUSIONS: This study reveals that PMsignificantly increases dementia risk in mood disorder patients, while healthy sleep patterns may mitigate this effect. These findings highlight the importance of air pollution control and sleep interventions in dementia prevention to reduce dementia risk in vulnerable populations. 2.5

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The relationship between air pollution and dementia in mood disorders: The moderating role of sleep patterns—— A prospective study from the UK Biobank

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