Table 2. Subgroup analyses for heterogeneity and group differences (chi2 and I2 tests).
| Subgroup | Heterogeneity chi2, df (P), I2 | Subgroup differences chi2 (P), I2 |
|---|---|---|
| Animal condition | 91.40, 21 (P<0.00001), 77% | 9.21, (P=0.002), 89.1% |
| Intact | 22.43, 11 (P=0.02), 51% | |
| Impaired | 43.95, 9 (P<0.00001), 80% | |
| Animal species# | 86.57, 20 (P<0.00001), 77% | 2.64, (P=0.10), 62.2% |
| Rat | 32.76, 10 (P=0.0003), 69% | |
| Mouse | 51.47, 9 (P<0.00001), 83% | |
| Type of drug | 91.40, 21 (P<0.00001), 77% | 7.72, (P=0.005), 87.0% |
| Extract | 14.80, 9 (P=0.10), 39% | |
| Active | 63.69, 11 (P<0.00001), 83% | |
| Duration of treatment | 91.40, 21 (P<0.00001), 77% | 0.03, (P=0.87), 0% |
| Acute | 18.13, 3 (P=0.0004), 83% | |
| Chronic | 71.55, 17 (P<0.00001), 76% | |
| Type of memory assessed* | 168.6, 34 (P<0.00001), 80% | 1.49, (P=0.22), 32.9% |
| Working | 131.2, 25 (P<0.00001), 81% | |
| Recognition | 37.39, 8 (P<0.00001), 79% |
#
The only study performed with zebra fish was omitted in the subgroup analysis.
*
All the individual experiments performed to assess memory were entered in the subgroup analysis.