Distribution of the ORCHID (Ordinal Regression Characteristic Index of Dementia) score extracted from for the ADNI dataset representing the disease progressive continuum spanning CTL to MCI-s to MCI-c to AD.

<p>The lower portion of each plot represents the distributions for the CTL class (green) and the AD class (red). (a) represents the distribution of subjects with unstable labels across follow-ups, most of which appear to belong to either the CTL or MCI-s classes (N = 24). (b) represents the distribution of those who convert to AD by 12 month follow-up (N = 62) (i.e. MCI-c: the sample used for training and testing the ADNI-based ORGP model). (c) represents the distribution of those who convert to AD between the 12 and 24 month follow-up (N = 58). (d) represents the distribution of those who convert to AD between the 24 and 36 month follow-up (N = 29).</p

Multivariate discriminative weights computed using ordinal regression.

<p>For ordinal regression the weights can be interpreted as the projection of the data along the function space weight vector spanning CTL to MCI-s to MCI-s to AD. Note that the weights are symmetric across hemispheres. These weights are sensitive the spatial correlations in the data and therefore should not be interpreted in a univariate manner.</p

Baseline subject characteristics.

<p>Data shown as mean ± standard deviation. Education is presented in years. ADNI subset refers to the group of reverters and later converters which were used for validation of the model but were not included in the training of the model. AD = Alzheimer’s disease, MCI = Mild Cognitive Impairment, CTL = healthy control, MMSE = Mini Mental State Examination. CDR-SOB – Clinical Dementia Rating – Sum Of Boxes.</p

Performance curves and correlation plots for ordinal regression.

<p>(A): ROC curves for ordinal regression applied to the ADNI data set using 10-fold cross-validation (first panel) and using the AddNeuroMed data set as an independent test set. In both cases the ROC curves are shown from three contrasts. (B): Correlation plots of the MMSE score assessed at the 12 month follow-up against the Ordinal Regression Characteristic Index of Dementia (ORCHID) score for both the ADNI dataset and the AddNeuroMed dataset.</p