Table 3.
General linear mixed models of premorbid intellectual disability (ID) level on PET Biomarkers
| Estimate (Standard Error) or F value | ||
| Aβ | Tau | |
| Site (random effect) | 0.554 | 0.498 |
| Age | 1.622 (0.233)** | 0.017 (0.002)** |
| Biological Sex | –2.033 (2.774) | –0.022 (0.031) |
| Trisomy type (versus full) | 0.531 | 0.481 |
| Mosaic | 2.443 (7.041) | 0.080 (0.087) |
| Translocation | –4.877 (5.087) | –0.018 (0.056) |
| APOE ɛ4 | 2.461(3.333) | 0.026 (0.036) |
| Clinical Status (versus CS) | 48.681** | 43.185** |
| MCI-DS | 37.720 (6.882)** | 0.437 (0.073)** |
| Dementia | 66.874 (7.411)** | 0.624 (0.078)** |
| Premorbid ID (versus mild) | 0.093 | 1.351 |
| Moderate | 2.53 (13.755) | –2.57 (0.155) |
| Severe/Profound | –7.823 (22.867) | –0.141 (0.256) |
| Age×Premorbid ID (versus mild) | 0.182 | 1.797 |
| Age×Moderate | –0.016 (0.354) | 0.008 (0.004) |
| Age×Severe/Profound | 0.349 (0.602) | 0.004 (0.007) |
ID, intellectual disability; CS, cognitively stable; MCI-DS, mild cognitive impairment-Down syndrome; Aβ, amyloid-beta assessed in centiloids. Age2 was not significantly related to Aβ (0.099 [0.067]) or Tau (0.003 [0.002]). Age2×Premorbid ID was not significantly related to Aβ (F = 0.134, p = 0.865) or Tau (F = 0.184, p = 0.465). *p < 0.05; **p < 0.01.