Table 1. Characteristics of ALFF studies included in the meta-analysis.
| Study | Sample (female) | Mean Age (SD) | UPDRS-III (SD) | H&Y stage (SD) | Duration (SD) | Medication status | Scanner | Software | FWHM | Threshold | Quality scores# |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Kwak et al.25 | PD 24 (2) HC 24 (5) | 64.3 (8) 63.3 (7) | 18.5 (8) | 2.2 (0.3) | 5.4 (3) | Off-state | 3.0 T | SPM5 | 8 mm | p < 0.001 uncorrected | 20 |
| Wen et al.19 | PD 16 (8) HC 21 (8) | 60.7 (18.7) 55.4 (16.4) | 33.8 (24.2) | 1.5 (1) | 5.6 (7.4) | Off-state | 3.0 T | SPM8, REST | 5 mm | p < 0.005 uncorrected | 20 |
| Possin et al.23 | PD 12 (9) HC 15 (11) | 73.9 (5.9) 72.9 (5.2) | 30.8 (14.5) | NA | 9 (7) | Off-state | 3.0 T | SPM8, REST | 4 mm | p < 0.05 corrected | 19 |
| Skidmore et al.13 | PD 14 (3) HC 15 (6) | 62 (9) 65 (13) | 37 (13) | NA | NA | Off-state | 3.0 T | AFNI | 6 mm | p < 0.005 uncorrected | 18 |
| Zhang et al.24 | PD 72 (37) HC 78 (32) | 59.7 (11.9) 58.6 (8.5) | 20.24 (8.44) | NA | 7.05 (6.01) | Off-state | 3.0 T | SPM8, REST | 8 mm | p < 0.05 corrected | 19 |
| Hou, et al.26 | PD 101 (42) HC 102 (42) | 59.84 (7.15) 59.91 (7.09) | 25.54 (11.51) | 1.87 (0.71) | 7.23 (4.42) | Off-state | 3.0 T | SPM8, DPARSF | 3 mm | p < 0.05 corrected | 20 |
| Luo et al.21 | PD 30 (15) HC 30 (15) | 53.64 (10.18) 51.9 (7.70) | 26.83 (12.44) | 1.73 (0.38) | 2.12 (1.30) | Off-state | 3.0 T | SPM8, REST | 8 mm | p < 0.001 corrected | 20 |
| Hu et al.17 | PD 17 (7) HC 20 (9) | 60.29 (12.03) 58.48 (6.89) | 17.11 (6.12) | NA | 3.94 (2.57) | Off-state | 3.0 T | SPM8, REST | 8 mm | p < 0.005 uncorrected | 19 |
| Chen et al.15 | PD1 12 (8) PD2 19 (7) HC 22 (10) | 62.6 (8.71) 64.8 (8.34) 65.1 (5.00) | 19.1 (11.5) 21.6 (11.6) | 1.87 (0.607) 2.13 (0.984) | 6.38 (4.01) 6.68 (4.85) | Off-state | 3.0 T | SPM8, REST | 4 mm | p < 0.05 corrected | 20 |
| Luo et al.18 | PD3 28 (14) PD4 28 (14) PD5 24 (11) HC 30 (15) | 52.45 (9.18) 54.12 (8.24) 54.41 (10.59) 53.53 (10.45) | 14.11 (6.45) 29.68 (8.22) 43.54 (12.65) | 1.0 (NA) 2.0 (NA) 3.0 (NA) | 1.56 (1.42) 3.78 (2.87) 5.31 (4.77) | Off-state | 3.0 T | SPM5, REST | 8 mm | p < 0.001 uncorrected | 19 |
| Xiang et al.27 | PD 24 (12) HC 24 (12) | 62.7 (7.4) 65.6 (6.9) | 22.0 (7.0) | 2.2 (0.9) | 7.0 (3.3) | Off-state | 3.0 T | SPM8, REST | 8 mm | p < 0.01 corrected | 20 |
Key: ALFF, amplitude of low-frequency fluctuations; PD, Parkinson’s disease; HC, healthy controls; SD, standard deviation; UPDRS-III, Unified Parkinson’s Disease Rating Scale, Part III; H&Y, Hoehn and Yahr disability scale; FWHM, full width at half maximum; NA, not available; AFNI, Analysis of Functional NeuroImage software; fMRI, functional magnetic resonance imaging; SPM, statistical parametric mapping; REST, the Resting-State fMRI Data Analysis Toolkit; 1postural instability/gait difficulty subtype of PD; 2tremor-dominant subtype of PD; 3PD patients at H&Y stage I; 4PD patients at H&Y stage II; 5PD patients at H&Y stage III; #a maximum score of 20 for each study.