Table 4.
Bivariate latent change score structural equation models examining the direct effect of PM2.5 exposure on changes in episodic memory and the indirect effect mediated by depressive symptoms (N = 2,202).
| CVLT Measures | |||
|---|---|---|---|
| Trials 1–3 | Short Delay Free Recall | Long Delay Free Recall | |
| β (95% CI) | β (95% CI) | β (95% CI) | |
| Estimatesa of Direct Effect | |||
| Effect of PM2.5 on annual change in episodic memory (γPM2.5 on Δem) | −1.26 (−1.90, −0.63) | −1.45 (−2.45, −0.75) | −1.00 (−1.70, −0.31) |
| Estimatesa of Indirect Effect | |||
| Effects of PM2.5 on annual changes in GDS-15 (γPM2.5 on Δdep) | 0.13 (−0.48, 0.64) | 0.09 (−0.52, 0.70) | 0.11 (−0.51, 0.72) |
| Effects of GDS-15 performance on annual change in episodic memory (γLdep on Δem) | −0.01 (−0.07, 0.05) | 0.04 (−0.01, 0.08) | 0.02 (−0.02, 0.06) |
| Indirect effect of PM2.5 on annual change in CVLT | −<0.01 (−0.01, 0.01) | <0.01 (−0.02, 0.03) | <0.01 (−0.01, 0.02) |
Abbreviations: CVLT = California Verbal Learning Test
Estimates bolded if statistically significant at p<0.05
All estimates derived from the bivariate structural equation models (SEM) as depicted in figure 2 panel B, with PM2.5 scaled by baseline interquartile range (4.04 μg/m3). In all models, the effect of time-varying PM2.5 exposure on initial CVLT performance, and on initial GDS-15 were adjusted for initial age, race/ethnicity, geographic region of residence, education, household income, lifestyle factors (smoking, alcohol use, physical activities), clinical characteristics (use of hormone treatment; hypercholesterolemia, hypertension, diabetes, and history of cardiovascular disease)