. Author manuscript; available in PMC: 2022 Feb 1.

Published in final edited form as: J Am Geriatr Soc. 2020 Nov 17;69(2):474–484. doi: 10.1111/jgs.16889

Table 3.

Bivariate latent change score structural equation models examining the direct effect of recent and remote exposure to NO₂ and PM_2.5 on changes in episodic memory as well as the respective indirect effect mediated by depressive symptoms (N = 1,583).

	Exposure: NO₂
	Remote^a Exposure	Recent^b Exposure
	Est^d (95% CI)	Est^d (95% CI)
Estimates of Direct Effect^c
Effect of NO₂ on annual change in episodic memory (γ_{NO2 on Δem})	.179 (−.119; .477)	−.024 (−.425; .377)

Estimates of Indirect Effect^c
Effects of NO₂ on annual changes in GDS-15 (γ_{NO2 on Δdep})	.255 (.074; .436)	.203 (−.042; .447)

Effects of GDS-15 performance on annual change in episodic memory (γ_{Ldep on Δem})	−.372 (−.594; −.150)	−.384 (−.615; −.154)

Indirect effect of NO₂ on annual change in episodic memory (γ_{NO2 on Δdep *} γ_{Ldep on Δem})	−.095 (−.171; −.026) ^e	−.078 (−.184; .018)^e

	Exposure: PM_2.5
	Remote^a Exposure	Recent^b Exposure
	Est^d (95% CI)	Est^d (95% CI)
Estimates of Direct Effect^c
Effect of PM_2.5 on annual change in episodic memory (γ_{PM2.5 on Δem})	.114 (−.149; .377)	.154 (−.183; .491)

Estimates of Indirect Effect^c
Effects of PM_2.5 on annual changes in GDS-15 (γ_{PM2.5 on Δdep})	.138 (−.004; .280)	.123 (−.081; .328)

Effects of GDS-15 performance on annual change in episodic memory (γ_{Ldep on Δem})	−.377 (−.608; −.146)	−.380 (−.612; −.148)

Indirect effect of PM_2.5 on annual change in episodic memory (γ_{PM2.5 on Δdep *} γ_{Ldep on Δem})	−.052 (−.112; −.001) ^e	−.047 (−.130; .035)^e

Abbreviations: NO₂ = nitrogen dioxide; PM_2.5 = particulate matter with <2.5 μm; episodic memory = latent factor consisting of the immediate and delayed recall from the East Boston Memory Test and the world list memory from the Telephone Interview for Cognitive Status; depressive symptoms = 15-item Geriatric Depression Scale, CI = Confidence interval, Est = parameter estimate

Estimates bolded if statistically significant at p<0.05

Remote represents the 3-year average exposures to regional PM_2.5 and NO₂ 10 years prior to study baseline

Recent represents the 3-year average exposures to regional PM_2.5 and NO₂ for the 3 years prior to study baseline

All effects below were derived from the bivariate structural equation models (SEM) as depicted in figure 2 panel A, with exposure scaled by interquartile range from the remote period ( PM_2.5 scaled by 3.35 μg/m³ and NO₂ scaled by 9.55 ppb).

In all models, the effects were adjusted for initial age at WHIMS-ECHO, race/ethnicity, geographic region of residence, employment status, education, household income, lifestyle factors (smoking, alcohol use, physical activities), clinical characteristics (use of hormone treatment; hypercholesterolemia, hypertension, diabetes, and history of cardiovascular disease), and neighborhood socioeconomic characteristics.

95% confidence interval for the indirect effect is asymmetric and estimated via Monte Carlo Simulation