Table 3.
Random Forest importance parameters (mean minimal depth, number of nodes, number of trees, times a root, accuracy decrease, Gini decrease, and p-value) and direction of significance for the top significant variables (p < 0.05) are shown. All 4 of the impulsivity scores [total, non-planning (NP), motor (MI), and attentional (AI)], 14 FC connections, and 2 neuropsychological scores from the visual span test (span and total correct scores of the forward condition) were found to be important to classify individuals into either alcohol use disorder or control group. The variables are sorted based on p-values.
| Variable | Mean Minimal Depth | No. of Trees | No. of Nodes | Times a Root | Accuracy Decrease | Gini Decrease | p-Value | Direction |
|---|---|---|---|---|---|---|---|---|
| BIS_Tot | 1.0667 | 75 | 75 | 27 | 0.0129 | 1.2864 | <0.0000 | Alc > Ctl |
| Be_s7_s11 (L.PFC–L.PHG) | 2.1804 | 48 | 49 | 20 | 0.0052 | 0.6907 | <0.0000 | Alc > Ctl |
| BIS_MI | 2.3889 | 46 | 47 | 18 | 0.0059 | 0.6928 | <0.0000 | Alc > Ctl |
| BIS_NP | 2.7201 | 37 | 37 | 13 | 0.0016 | 0.5271 | <0.0000 | Alc > Ctl |
| De_s7_s8 (L.PFC–R.PFC) | 2.8268 | 37 | 37 | 10 | 0.0021 | 0.4859 | <0.0000 | Ctl > Alc |
| TotCor_Fw | 2.7327 | 34 | 35 | 17 | 0.0058 | 0.5137 | <0.0000 | Ctl > Alc |
| Al_s9_s11 (L.LTC–L.PHG) | 2.7503 | 33 | 33 | 18 | 0.0035 | 0.5437 | <0.0000 | Alc > Ctl |
| De_s2_s4 (R.PCC–R.ACC) | 3.1145 | 32 | 32 | 7 | 0.0034 | 0.3497 | <0.0000 | Alc > Ctl |
| Al_s3_s7 (L.ACC–L.PFC) | 3.3615 | 24 | 25 | 5 | 0.0007 | 0.3068 | <0.0000 | Alc > Ctl |
| Al_s10_s12 (R.LTC–R.PHG) | 3.3791 | 23 | 24 | 6 | 0.0023 | 0.2278 | 0.0001 | Alc > Ctl |
| BIS_AI | 3.3615 | 24 | 24 | 6 | 0.0022 | 0.2915 | 0.0001 | Alc > Ctl |
| Al_s8_s9 (R.PFC–L.LTC) | 3.3300 | 22 | 23 | 11 | 0.0015 | 0.2610 | 0.0002 | Alc > Ctl |
| De_s2_s8 (R.PCC–R.PFC) | 3.5566 | 22 | 22 | 2 | −0.0006 | 0.2333 | 0.0004 | Alc > Ctl |
| Ga_s11_s12 (L.PHG–R.PHG) | 3.5700 | 22 | 22 | 3 | 0.0011 | 0.2048 | 0.0004 | Alc > Ctl |
| Be_s2_s11 (R.PCC–L.PHG) | 3.5209 | 21 | 21 | 5 | 0.0004 | 0.1963 | 0.0010 | Alc > Ctl |
| Be_s2_s8 (R.PCC–R.PFC) | 3.5209 | 21 | 21 | 7 | 0.0007 | 0.2348 | 0.0010 | Alc > Ctl |
| De_s10_s12 (R.LTC–R.PHG) | 3.5475 | 21 | 21 | 4 | 0.0004 | 0.2319 | 0.0010 | Alc > Ctl |
| TotCorAvgTime_Fw | 3.5251 | 20 | 20 | 6 | 0.0005 | 0.1813 | 0.0023 | Alc > Ctl |
| Al_s7_s12 (L.PFC–R.PHG) | 3.6802 | 18 | 19 | 4 | 0.0011 | 0.1598 | 0.0049 | Alc > Ctl |
| Ga_s4_s5 (R.ACC–L.IPL) | 3.6268 | 18 | 19 | 6 | 0.0001 | 0.2065 | 0.0049 | Alc > Ctl |
| De_s6_s8 (R.IPL–R.PFC) | 3.6226 | 19 | 19 | 5 | 0.0009 | 0.1804 | 0.0049 | Ctl > Alc |
| Ga_s4_s9 (R.ACC–L.LTC) | 3.5826 | 19 | 19 | 3 | −0.0004 | 0.1558 | 0.0049 | Alc > Ctl |
| Al_s6_s9 (R.IPL–L.LTC) | 3.5068 | 18 | 18 | 9 | 0.0007 | 0.2273 | 0.0101 | Alc > Ctl |
| Th_s1_s11 (L.PCC–L.PHG) | 3.5868 | 18 | 18 | 4 | 0.0011 | 0.1981 | 0.0101 | Alc > Ctl |
| TotCor_Bw | 3.6177 | 17 | 17 | 5 | 0.0007 | 0.1670 | 0.0199 | Ctl > Alc |
| Be_s2_s7 (R.PCC–L.PFC) | 3.6044 | 17 | 17 | 6 | 0.0008 | 0.2282 | 0.0199 | Alc > Ctl |
| Be_s3_s12 (L.ACC–R.PHG) | 3.7644 | 17 | 17 | 3 | 0.0004 | 0.1473 | 0.0199 | Ctl > Alc |
| Be_s8_s9 (R.PFC–L.LTC) | 3.7377 | 17 | 17 | 0 | −0.0005 | 0.1421 | 0.0199 | Alc > Ctl |
| Th_s4_s11 (R.ACC–L.PHG) | 3.5510 | 17 | 17 | 7 | 0.0006 | 0.2227 | 0.0199 | Alc > Ctl |
| Th_s5_s8 (L.IPL–R.PFC) | 3.5910 | 17 | 17 | 6 | 0.0001 | 0.1889 | 0.0199 | Alc > Ctl |
| Th_s6_s11 (R.IPL–L.PHG) | 3.7244 | 17 | 17 | 4 | 0.0002 | 0.1411 | 0.0199 | Alc > Ctl |
| De_s8_s10 (R.PFC–L.PCC) | 3.7953 | 16 | 16 | 2 | −0.0009 | 0.1738 | 0.0371 | Ctl > Alc |
| Ga_s2_s8 (R.PCC–R.PFC) | 3.7153 | 16 | 16 | 3 | 0.0003 | 0.1712 | 0.0371 | Alc > Ctl |
| Ga_s3_s12 (L.ACC–R.PHG) | 3.7153 | 16 | 16 | 4 | 0.0005 | 0.1858 | 0.0371 | Alc > Ctl |
| Th_s2_s9 (R.PCC–L.LTC) | 3.8219 | 16 | 16 | 2 | 0.0006 | 0.1398 | 0.0371 | Alc > Ctl |
| Th_s8_s12 (R.PFC–R.PHG) | 3.7019 | 16 | 16 | 1 | 0.0005 | 0.1510 | 0.0371 | Alc > Ctl |
De–Delta; Th–Theta; Al–Alpha; Be–Beta; Ga–Gamma; L–Left; R–Right; PCC–Posterior cingulate cortex; ACC–Anterior cingulate cortex; IPL–Inferior parietal lobule; PFC–Prefrontal cortex; LTC–Lateral temporal cortex; PHG–Parahippocampal gyrus; VST–Visual Span Test [s1:s12–seeds 1-12 of the default mode network].