Table 1.
Representative Autism Case-Control Classification Studies
| Study | Data Source | n | Age, Years, Mean ± SD or Range | Male, % | Algorithm | Features | Validation | Accuracy (Sensitivity, Specificity) | Notes |
|---|---|---|---|---|---|---|---|---|---|
| (68) | Lab-specific | 40 autism 40 NT |
8–42 | 100% | – | FC from 7266 × 7266 ROIs | Internal (leave-one-out CV); external validation in independent sample | 79% (83%, 75%) | External validation results: 71% accuracy, 75% sensitivity, and 69% specificity |
| (50) | Lab-specific | 13 autism 14 NT |
Autism: 21.4 ± 3.9 NT: 22.6 ± 4.2 |
100% | LRC | FC from 102 × 102 ROIs (AAL atlas) (139); seed-based connectivity | Internal (leave-one-out CV) | 77.8% (76.9%, 78.6%) | Whole-brain classification results reported; seed-based accuracies ranged from 70% to 96% |
| (53) | Lab-specific | 29 autism 29 NT |
– | 83% | LRC | FC from 106 × 106 ROIs (AAL atlas) (139) | Internal (leave-one-out CV) | (82.8%, 82.8%) | – |
| (52) | Lab-specific | 20 autism 20 NT |
Autism: 9.96 ± 1.59 NT: 9.95 ± 1.60 |
80% | LRC | Network FC maps (10 components) | Internal (leave-one-out CV); external validation in independent sample | 78% (75%, 80%) | Best performing network (salience network) is shown External validation results: 83% accuracy, 67% sensitivity, 100% specificity |
| (46) | ABIDE | 126 autism 126 NT |
6–36 | 85% | RF | FC from 220 × 220 ROIs (Power atlas) (140) | Bootstrapping CV (one third left out); external validation set | 91% (89%, 93%) | Various SVM pipelines also tested, with the highest accuracy obtained = 66% |
| (51) | Lab-specific | 59 autism 59 NT |
Autism: 17.66 ± 2.72 NT: 18.3 ± 3.05 |
100% | Various tested | Various tested | Internal (leave-one-out, stratified 3-fold, stratified 10-fold CV) | 76.7% (70%, 83.3%) | Pipeline with the highest accuracy and positive predictive values is shown Classifier: SVM; features: FC from 162 × 162 ROIs (Destrieux atlas); validation: leave-one-out CV |
| (49) | ABIDE | 312 autism 328 NT |
6–19 | 84% | NN | FC from 90 × 90 ROIs (AAL atlas) (139) | Internal (leave-one-out, various k-fold CV strategies tested) | 89.4% (92%, 87%) | Showing results for leave-one-out |
| (47) | ABIDE | 112 autism 128 NT |
12–18 | 85% | SVM | FC from 142 × 142 ROIs (Dosenbach atlas) (141); multiple frequency bands used | Internal (leave-one-out, 10-fold CV); leave-one-site-out CV | 79.2% (77.8%, 80.5%) | Showing results for leave-one-out |
| (54) | Lab-specific, ABIDE | Lab-specific: 74 autism, 107 NT ABIDE: 44 autism, 44 NT |
Lab-specific: ~30 ± 8 per site ABIDE: site-specific |
82% | LRC | FC from 140 × 140 ROIs (extended BrainVisa Sulci atlas) (142) | Internal (leave-one-out CV); external validation | 85% (80%, 89%) | Results are reported for leave-one-out; accuracy on external data = 75% |
| (48) | IBIS | 11 autism 48 HR |
2 | 69% | SVM | FC from 230 × 230 ROIs (including nodes from Power atlas) (140) | Internal (leave-one-out CV) | 96.6% (81.8%, 100%) | – |
| (55) | ABIDE | 55 autism 55 NT |
8–19 | 76% | NN | FC from 116 × 116 ROIs (AAL atlas) (139) | Internal (5-fold nested CV) | 86.36% | – |
| (57) | ABIDE | 126 autism 126 NT |
7–36 | 81% | RF, CRF | FC from 220 × 220 ROIs (Power atlas) (140) | External validation sample | 66.7% | Highest accuracy using CRF in validation dataset shown here; highest accuracy using RF in validation data = 71% |
| (12) | ABIDE | 403 autism 468 NT |
Site-specific | Site-specific | SVM | Various tested | Internal (10-fold CV); leave-one-site-out CV | 66.8% | Highest accuracy obtained in leave-one-site-out analyses using a dictionary learning-based atlas (143) |
| (56) | ABIDE | 505 autism 530 NT |
Site-specific | Site-specific | NN | FC from 200 × 200 ROIs (Craddock atlas) (144) | Internal (5-fold, 10-fold CV); leave-one-site-out CV | 70 (74%, 63%) | Showing results for 10-fold CV |
| (58) | ABIDE | 816 autism + NT | 5–65 | – | SVM | GT properties (AAL atlas) (139) | Internal (10-fold CV) | 95% (97%, 91%) | Highest accuracy obtained across various pipelines, age groups (obtained in 30+ year olds) using sparse inverse covariance to estimate connectivity GT properties included various measures of integration, segregation, and centrality |
| (59) | ABIDE | 505 autism 530 NT |
Site-specific | Site-specific | NN | FC from 200 × 200 ROIs (Craddock atlas) (144) | Internal (5-fold, 10-fold CV) | 70.3% (68.3%, 72.2%) | Showing results for 10-fold CV |
| (60) | ABIDE | 408 autism 401 NT |
Autism: 16.5 ± 6.7 NT: 16.8 ± 7.8 |
84% | NN | Various tested | Internal (various k-fold CV strategies tested); leave-one-site-out CV | 73.2% (74.5%, 71.7%) | Showing results for 10-fold CV using a combination of features from AAL + HO + Craddock atlases, along with demographic data |
| (61) | ABIDE | 506 autism 548 NT |
16.86 ± 7.55 | 85% | SVM | FC from 200 × 200 ROIs (Craddock atlas) (144) | Internal (10-fold nested CV) | 72.2% (68.6%, 75.4%) | – |
| (62) | ABIDE | 505 autism 530 NT |
Site-specific | Site-specific | NN | FC from 392 × 392 ROIs (Craddock atlas) (144) | Internal (10-fold CV); leave-one-site-out CV | 70.2% (77.5%, 61.8%) | Showing results for 10-fold CV |
| (63) | ABIDE | 505 autism 530 NT |
– | – | NN | FC from 116 × 116 ROIs (AAL atlas) (139); voxel-wise × ROI FC | Internal (test set validation) | 74% | – |
| (64) | ABIDE | 45 autism 47 NT |
7–15 | 78% | SVM | FC from 116 × 116 ROIs (AAL atlas) (139); various dFC measures | Internal (6-fold nested CV) | 83% (82%, 84%) | Showing results from a combination of FC and dFC measures that resulted in best performance |
| (65) | ABIDE | 505 autism 530 NT |
– | – | NN | FC from 200 × 200 ROIs (Craddock atlas) (144) | Internal (10-fold nested CV); leave-one-site-out CV | 76.4% (77.8%, 75%) | Showing results from 10-fold CV |
| (66) | ABIDE | 403 autism 468 NT |
– | – | NN | FC from 264 × 264 ROIs (Power atlas) (140) | Internal (10-fold CV) | 79.2% | – |
| (67) | ABIDE | 306 autism 350 NT |
6–18 | Varied by analysis | RF | FC from 237 × 237 ROIs [Gordon (145) + HO subcortical (146) + cerebellar (147) atlases] | Bootstrapping CV (one third left out) | 62.5% (60%, 65%) | Main sample size is shown here; different subsamples were tested consisting of n = 200 with autism and n = 200 NT participants Results from subsample including males and females with no ADOS score cutoffs |
Table adapted with permission from (9). Note that studies are arranged in chronological order such that more recent studies are at the bottom of the table.
AAL, automated anatomical labeling; ABIDE, Autism Brain Imaging Data Exchange; ADOS, Autism Diagnostic Observation Schedule; CRF, conditional random forest; CV, cross-validation; dFC, dynamic functional connectivity; FC, functional connectivity; GT, graph theory; HO, Harvard-Oxford atlas; HR, high risk; IBIS, Infant Brain Imaging Study; LRC, logistic regression classifier; NN, neural network; NT, neurotypical; RF, random forest; ROI, region of interest; SVM, support vector machine.