Table 3. Comparison between depressed subjects with MDD only, versus those with primary PTSD and comorbid MDDand healthy controls (HC).
| Parameters | Estimate | SEM | t | p | 95% CI boot
|
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| (bias) | Lower Limit | Upper Limit | ||||||||||||
| Early Discounting (β) | ||||||||||||||
| HC | 0.664 (0.007) | 0.134 | 4.974 | <0.001 | 0.4101 | 0.9967 | ||||||||
| MDD only | 1.370 (0.053) | 0.297 | 4.613 | <0.001 | 0.862 | 2.374 | ||||||||
| MDD + PTSD | 1.800 (0.498) | 0.442 | 4.072 | <0.001 | 1.002 | 8.652 | ||||||||
| Group differences in early discounting (β* g) | ||||||||||||||
| HC vs. MDD only | 0.706 (0.005) | 0.326 | 2.168 | 0.031 | 0.1028 | 1.6968 | ||||||||
| HC vs. MDD + PTSD | 1.136 (0.490) | 0.462 | 2.460 | 0.014 | 0.265 | 8.065 | ||||||||
| MDD only vs. MDD + PTSD | 0.430 (0.445) | 0.533 | 0.807 | 0.420 | -0.7816 | 7.0652 | ||||||||
| Late Discounting over gains (δ) | ||||||||||||||
| HC | -0.012 (0.001) | 0.013 | 1.752 | 0.081 | -0.0336 | 0.0123 | ||||||||
| MDD only | 0.030 (0.001) | 0.022 | 0.507 | 0.612 | 0.0006 | 0.0632 | ||||||||
| MDD + PTSD | 0.057 (0.002) | 0.025 | 3.332 | <0.001 | 0.0126 | 0.1034 | ||||||||
| Late Discounting over losses (δ* l) | ||||||||||||||
| HC | -0.034 (-0.001) | 0.008 | -4.431 | <0.001 | -0.0502 | 0.004 | ||||||||
| MDD only | 0.019 (-0.000) | 0.014 | 1.369 | 0.172 | -0.0558 | 0.0352 | ||||||||
| MDD + PTSD | -0.027 (-0.002) | 0.011 | -2.613 | 0.009 | -0.1326 | -0.0353 | ||||||||
| Group differences in late discounting over gains (δ* g) | ||||||||||||||
| HC vs. MDD only | 0.042 (-0.0002) | 0.020 | 2.132 | 0.034 | 0.0035 | 0.0817 | ||||||||
| HC vs. MDD + PTSD | 0.069 (0.0005) | 0.025 | 2.726 | 0.007 | 0.0194 | 0.1233 | ||||||||
| MDD only vs. MDD + PTSD | 0.027 (0.0007) | 0.029 | 0.932 | 0.352 | -0.0285 | 0.0835 | ||||||||
| Group differences in late discounting over losses (δ* g* l) | ||||||||||||||
| HC vs. MDD only | 0.011 (0.0005) | 0.025 | 0.441 | 0.659 | -0.0417 | 0.0652 | ||||||||
| HC vs. MDD + PTSD | -0.062 (-0.001) | 0.028 | -2.191 | 0.029 | -0.1179 | -0.0069 | ||||||||
| MDD only vs. MDD + PTSD | -0.073 (0.001) | 0.034 | -2.189 | 0.029 | -0.1400 | -0.0071 | ||||||||
Results from best fitting quasi-hyperbolic model and bootstrap analysis showing parameter estimates for each group and group differences in early and late discounting over gains and losses.
β: early discounting, δ: late discounting, g: effect of group on discounting slope, l: effect of loss on discounting slope. Parameter estimates are shown together with their estimated bias based on bootstrap analyses (in brackets), respective standard errors (SEM), t statistic, p values, and 95% confidence intervals from confirmatory nonparametric bootstrap analyses.
Parameter estimates reflect quasi-hyperbolic intertemporal choice functions for each group (β, δ and, δ * l). Interactions with the group dummy (g) reflect differences in slopes between groups for delays smaller than one year (β* g), as well as delays greater than one year in the domain of gains (δ* g) and losses (δ* g * l).