Table 2.
Summary of meta-analyses comparing mean group differences in cognitive functioning between autism and schizophrenia.
| Cognitive Domain | Number of Studies | Combined ASD n | Combined SZ n | ASD Scaled Score | SZ Scaled Score | Effect Size | Effect Size 95% C.I. | Effect Size p-value | I2 | ERT (p-value) | Fail-Safe n |
|---|---|---|---|---|---|---|---|---|---|---|---|
| VCI: Similarities | 6 | 260 | 190 | 10.81 (0.47) | 9.42 (0.97) | 0.389 | (-0.061, 0.839) | .090 | 77.0 | 1.027 (.305) | – |
| VCI: Information | 5 | 247 | 177 | 11.84 (0.54) | 10.81 (0.90) | 0.287 | (-0.034, 0.608) | .079 | 53.5 | -0.797 (.425) | – |
| VCI: Vocabulary | 4 | 215 | 160 | 9.98 (0.48) | 9.06 (0.61) | 0.275* | (0.031, 0.519) | .027 | 10.9 | -0.736 (.462) | 4 |
| VCI: Comprehension | 5 | 247 | 177 | 9.81 (0.82) | 8.81 (0.74) | 0.321 | (-0.063, 0.704) | .101 | 66.9 | -0.043 (.966) | – |
| PRI: Block Design | 6 | 260 | 190 | 10.84 (0.33) | 8.82 (0.75) | 0.636** | (0.177, 1.095) | .007 | 77.4 | 0.488 (.626) | 65 |
| PRI: Picture Completion | 4 | 215 | 160 | 9.30 (0.55) | 8.26 (0.44) | 0.433*** | (0.203, 0.663) | <.001 | 0.0 | -1.923 (.055) | 13 |
| WMI: Digit Span | 6 | 260 | 190 | 9.74 (0.35) | 8.96 (0.41) | 0.213 | (-0.051, 0.476) | .113 | 35.4 | 0.994 (.320) | – |
| WMI: Arithmetic | 5 | 247 | 177 | 10.10 (0.56) | 8.98 (0.63) | 0.334* | (0.056, 0.612) | .019 | 38.4 | -0.236 (.814) | 12 |
| PSI: Digit Symbol Coding | 6 | 260 | 190 | 7.93 (0.71) | 6.73 (0.45) | 0.385 | (-0.056, 0.826) | .087 | 76.1 | 0.851 (.395) | – |
| Object Assembly | 4 | 215 | 160 | 10.25 (0.32) | 8.64 (0.80) | 0.475* | (0.083, 0.868) | .018 | 63.8 | -0.593 (.553) | 20 |
| Picture Arrangement | 4 | 215 | 160 | 9.45 (0.84) | 7.72 (0.68) | 0.672 | (-0.054, 1.397) | .070 | 88.9 | -1.318 (.187) | – |
ASD, autism spectrum disorder; SZ, schizophrenia; VCI, Verbal Comprehension Index; PRI, Perceptual Reasoning Index; WMI, Working Memory Index; PSI, Processing Speed Index.
For scaled scores, means weighted by group inverse variance are presented with standard errors in parentheses. Scaled scores are age-adjusted to have a sample distribution centered at a mean of 10 and a standard deviation of 3 (range=1-19), with higher scores indicating better performance.
C.I., confidence interval. *p<.05; **p<.01; ***p<.001.
I2 (31): percentage of variation across studies that is due to heterogeneity rather than chance.
ERT [Egger’s Regression Test; (32)]: correlation between effect sizes and sample sizes.
Fail-safe n: number of studies with null results that would have to be added to the current set of studies to raise the significance level of the effect size to p=.05 (33).