TOPLINE:

Contrary to what the authors had hypothesized, stroke and hypertension should not vital mediators of the affiliation between positive particulate matter (PM_2.5) and dementia, findings from a nationally consultant cohort examine present, suggesting extra investigation is required into how publicity to air air pollution can have an effect on dementia threat.

METHODOLOGY:

• For this examine, the authors hypothesized vascular dysfunction (stroke and hypertension) might act as a mediator of the affiliation of PM_2.5 with dementia, given the affiliation of PM_2.5 with vascular circumstances, and of vascular circumstances with dementia.

• The examine included 27,857 contributors from the Health Retirement Study (HRS), a nationally consultant cohort of older Americans, imply age 61 years, who had been with out dementia at baseline and had no less than 1 follow-up interview between 1998 and 2016.

• Researchers estimated PM_2.5 concentrations on the premise of residential addresses throughout the 10 years previous to baseline and used causal mediation modeling to quantify the diploma to which stroke and hypertension might be mediators and/or modifiers of the affiliation of PM_2.5 with incident dementia, which they labeled utilizing a standardized strategy from survey respondents or their proxies.

TAKEAWAY:

• After a imply follow-up of 10.2 years, 14.7% of examine contributors developed dementia; of those, 53.7% had a historical past of hypertension at baseline and 9.4% obtained a prognosis of hypertension throughout the follow-up, whereas 9.2% had a historical past of stroke at baseline and 16.4% had a stroke over the follow-up interval.

• With adjustment for covariates, larger ranges of PM_2.5 weren’t related to elevated threat of stroke (odds ratio [OR] per interquartile vary (IQR) distinction in PM_2.5, 1.08; 95% CI, 0.91 – 1.29).

• There was no affiliation of PM_2.5 with prevalent hypertension (OR per IQR increment in PM_2.5, 0.99; 95% CI, 0.92 – 1.07).

• Sensitivity analyses discovered constant outcomes when the examine was restricted to youthful contributors and time intervals with larger high quality publicity information, and a urged affiliation of PM_2.5 with incident dementia amongst these with hypertension at baseline, with no related interplay for stroke.

IN PRACTICE:

As the examine did not present proof that hypertension or stroke mediated or modified the affiliation of PM_2.5 with incident dementia, “additional investigation of the pathways underlying the association of air pollution with dementia is needed to understand disease etiology and identify populations who might benefit most from pollution reduction strategies,” the authors write.

SOURCE:

The examine was carried out by Boya Zhang, PhD, Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, and colleagues. It was published online September 20  in JAMA Network Open.

LIMITATIONS:

The examine used the 10-year common publicity earlier than baseline, which can have resulted in an underestimation of the affiliation of PM_2.5 with dementia and diminished energy to seize mediation associations. Estimating PM_2.5 ranges from residential historical past moderately than real-time areas might have led to measurement error, and use of self-reported mediators might have launched misclassification of hypertension and stroke.

DISCLOSURES:

The Health and Retirement Study (HRS) was funded by the National Institute on Aging (NIA) and the Social Security Administration, and the examine was supported by the National Institutes for Environmental Health Sciences and NIA. Zhang has disclosed no related monetary relationships; see paper for disclosures of different authors.

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