Table 5.
Mediation by education of the associations of race with cognitive score and Alzheimer’s dementia risk.
| Adjusteda difference (95% CI) between black and white participants’ baseline cognitive scores | Adjusteda relative risk (95% CI) of incident Alzheimer’s dementia among black versus white participants | |
|---|---|---|
| N = 7335 | N = 2827 | |
| Estimated total effect | Estimated effect of race (black compared with white) on cognitive performance through all causal pathways. | |
| −0.69 (−0.73, −0.65) | 1.49 (1.05, 2.01) | |
| Estimated natural direct effect | Estimated effect of race (black compared with white) on cognitive performance through pathways other than those involving years of education. | |
| −0.45 (−0.49, −0.41) | 1.30 (0.91, 1.78) | |
| Estimated controlled direct effect | Estimated effect of race (black compared with white) on cognitive performance under the scenario in which everyone attains the same specified years of education.b | |
| Everyone attains 12 years of education | −0.57 (−0.62, −0.53) | 1.30 (0.91, 1.78) |
| Everyone attains 16 years of education | −0.29 (−0.35, −0.24) | |
| Proportion of effect eliminated by setting years of education to specified level | Proportion of difference eliminatedc | Proportion of excess relative risk eliminatedb,d |
| Everyone attains 12 years of education | 17% | 37% |
| Everyone attains 16 years of education | 58% | |
a
Adjusted for age, sex, and childhood socioeconomic resources.
b
With no interaction between race and education with respect to Alzheimer’s dementia risk, the estimated natural direct effect and controlled direct effects are equivalent, and the controlled direct effect and proportion of effect eliminated do not vary by years of education.
c
[(Total Effect - Controlled Direct Effect)/(Total Effect)].
d
[RR(Total Effect) - RR(Controlled Direct Effect)]/[RR(Total Effect)-1]. Excess relative risk is the portion of the relative risk that exceeds 1, i.e., RR − 1.