Table 2.
Linear and polynomial effects of age on global cerebral blood flow in Down syndrome: coefficients, 95% confidence intervals, T-statistic and P values
| Characteristic | Linear | Polynomial | Mediation |
|---|---|---|---|
| Age | β = −0.13 (95% CI: −0.41 to 0.16) | β = 2.26 (95% CI: 0.98 to 4.17) | β = 2.13 (95% CI: 0.26 to 4.01) |
| t = −0.88; P = 0.39 | t = 2.32; P = 0.03 | t = 2.23; P = 0.03 | |
| Age2 | β = −0.03 (95% CI: −0.05 to −0.01) | β = −0.02 (95% CI: −0.04 to −0.01) | |
| t = −2.47; P = 0.02 | t = −2.28; P = 0.03 | ||
| Total grey volume | β = 94.97 (95% CI: 26.84 to 163.09) | β = 89.77 (95% CI: 26.52 to 153.02) | β = 67.02 (95% CI: 6.57 to 127.47) |
| t = 2.73; P = 0.02 | t = 2.78; P = 0.01 | t = 2.17; P = 0.04 | |
| Residual arterial sign: severe vs. mild | – | – | β = −9.18 (95% CI: −16.89 to −1.46) |
| t = −2.33; P = 0.03 | |||
| Residual arterial sign: moderat vs. mild | – | – | β = −5.07 (95% CI: −11.40 to 1.26) |
| t = −1.57; P = 0.13 | |||
| Residual arterial sign: none vs. mild | – | – | β = 2.15 (95% CI: −5.15 to 9.45) |
| t = 0.58; P = 0.57 | |||
| Intercept | β = 20.33 (95% CI: −8.98 to 49.63) | β = −28.29 (95% CI: −75.43 to 18.84) | β = −18.77 (95% CI: −65.98 to 28.43) |
| t = 1.36; P = 0.19 | t = 1.18; P = 0.25 | t = −0.78; P = 0.44 | |
| Observations | 34 | 34 | 34 |
| R2 | 0.32 | 0.43 | 0.57 |
| Adjusted R2 | 0.27 | 0.37 | 0.47 |
| AIC | 244.77 | 240.46 | 237.17 |
| BIC | 250.87 | 248.09 | 249.38 |
| F statistic | 7.132,31; P = 0.003 | 7.583,30; P < 0.001 | 7.026,27; P < 0.001 |
AIC, Akaike information criterion; BIC, Bayesian information criterion; CI, confidence interval.