Table 2.
Proportion of decline in memory function (ADNI-Mem) explained by each biomarker progression
| Biomarker | Normal group |
Among MCI∗ |
Among AD |
|||
|---|---|---|---|---|---|---|
| % Variability explained by biomarkers | Standardized effect size | % Variability explained by biomarkers | Standardized effect size | % Variability explained by biomarkers | Standardized effect size | |
| Novel computerized marker (1 SD = 1.4) | 49.00 | −0.18 | 76.00 | −0.21 | 82.00 | −0.29 |
| t-tau progression (1 SD = 0.21) | N/A | — | N/A | — | N/A | — |
| Aβ42 progression (1 SD = 0.15) | 1.00 | 0.08 | 12.60 | −0.41 | 10.00 | −0.10 |
| FDG-PET progression (1 SD = 0.19) | 2.00 | 0.10 | 17.80 | 0.13 | 84.10 | 0.22 |
| Log_WMH/ICV progression (1 SD = 0.04) | N/A | — | N/A | — | 6.10 | 0.10 |
| HPCV/ICV progression (1 SD = 0.08) | N/A | — | 23.40 | 0.15 | 35.00 | 0.19 |
| Ventricles/ICV progression (1 SD = 0.13) | N/A | — | 43.80 | −0.18 | 73.80 | −0.21 |
| wbrain/ICV progression (1 SD = 0.11) | 6.00 | 0.07 | 26.00 | 0.10 | 30.40 | 0.19 |
| pthickness progression (1 SD = 0.10) | 2.94 | 0.05 | 6.58 | 0.09 | 8.31 | 0.11 |
| mtthickness progression (1 SD = 0.13) | 4.67 | 0.12 | 32.70 | 0.16 | 42.80 | 0.21 |
Abbreviations: ADNI-Mem, Alzheimer's Disease Neuroimaging Initiative-memory; MCI, mild cognitive impairment; AD, Alzheimer's disease; SD, standard deviation; t-tau, total tau; Aβ, amyloid beta; FDG-PET, fluorodeoxyglucose-positron emission tomography; WMH, white matter hyperintensity; ICV, intracranial volume; HPCV, hippocampal volume; wbrain, total brain volume; pthickness, precuneus thickness; mtthickness, medial temporal cortical thickness; APOE, apolipoprotein E.
NOTE. Brain volumes were divided by ICV. Controlling for age at baseline, sex, education, APOE ε4 allele (at least one vs. none), and practice effects.
NOTE. N/A: Variability increased instead of decreased or had no changes, after inclusion of the predictors in the model. For instance, including these variables, goodness of fit of the model compared with the null model did not improve because they did not explain the variability of cognitive outcomes or caused more estimation errors instead of explaining the variability.
To capture changes in diagnosis from MCI to AD during the follow-up, an indicator variable (before AD coded as 0, after AD coded as 1) was included as a control variable to factor in the shift in slopes in cognitive decline among MCI.