Fig. 4.

Estimates of the indirect effects in the spatial and verbal working memory structural equation models. The indirect effects (β) and 95% bias-corrected confidence intervals for each mediator variable were calculated using a bootstrap procedure with 20,000 samples. Indirect effects were significant for all mediator variables. However, note that some positive (blue or dark gray) and negative predictors (red or light gray) had opposite indirect effects when mediating the effects of age on working memory. The indirect effects are products of the effects of age on each mediator and the effects of each mediator on working memory. Thus, if both effects are positive or negative, then the indirect effects will be positive. However, if they have opposite effects, then their indirect effects will be negative. MMSE Mini-Mental State Scale, MIA Metamemory in Adulthood Scale, BMI body mass index, MAP mean arterial pressure, fr frequency. ^aTotal intake or time = frequency × duration. ^bLog-transformed variable (color figure online)