Fig. 1.

The multivariate structural equations model used to quantify cognitive reserve and assessed associations of determinants with cognitive reserve. Rectangles are observed variables and ovals are latent variables. Panel A depicts the definition of cognitive reserve as the residual variance of the regressions of five cognitive tests on MRI-scan inferred brain pathology and demographics. For simplicity, the model does not show the correlations among the observed variables. Panel B depicts the variables investigated in relation to cognitive reserve. Note that all cognitive, MRI and demographic variables listed in Panel A are included in the model, but not depicted in Panel B. 15WLT, the 15-word verbal learning test; STROOP, Stroop task; WFT, word fluency test; LDST, letter-digit substitution task; PPB, Purdue pegboard test; WMH, white matter hyperintensities; HT, hypertension; CVD, cardiovascular disease; COPD, chronic obstructive pulmonary disease.