FIGURE 4.

The relationship between brain age and SDMT, independent of chronological age. Left: Scatterplot between BPAD and SDMT in the MS_test dataset. The textbox describes the Pearson r statistic, along with the p value. Right: Forest plot visualizing the significance of the weights (β _n ) in the linear regression equation $\text{SDMT}={\beta }_0+{\beta }_1\text{BrainAge}+{\beta }_2\text{ChronologicalAge}+\epsilon$ in the MS_test dataset (note that variables were normalized with respect to mean and standard deviation before input in the regression equation). The maximum likelihood estimates of the weights (${\beta }_n$) are represented by the orange squares, along with a 95% confidence interval (horizontal bar). If the latter does not include 0, the contribution of that feature to the model is considered significant. Brain age and chronological age contributed significantly (p = 0.002 and p < 0.001 respectively) [Color figure can be viewed at wileyonlinelibrary.com]