Table 1.
Characteristics of the study population
| Females (n = 287) | Males (n = 341) | P-value | ||
|---|---|---|---|---|
| Age (years) | 44.5 [33.6; 50.8] | 44.0 [35.1; 50.7] | 0.91 | |
| APOE ɛ4 haplotype | 0.63 | |||
| ɛ4 carriers | 54 (21.4%) | 58 (19.4%) | ||
| ɛ4 non-carriers | 198 (78.6%) | 241 (80.6%) | ||
| Level of intellectual disability | 0.09 | |||
| Mild | 72 (25.7%) | 61 (18.4%) | ||
| Moderate | 144 (51.4%) | 184 (55.6%) | ||
| Severe or profound | 64 (22.9%) | 86 (26.0%) | ||
| Diagnostic group | 0.78 | |||
| Asymptomatic | 177 (66.0%) | 218 (67.5%) | ||
| Symptomatic Alzheimer’s disease | 91 (34.0%) | 105 (32.5%) | ||
| Medical conditions | ||||
| Hypothyroidism (n = 406) | 108 (58.7%) | 87 (39.2%) | <0.001 | |
| Epilepsy (n = 330) | 17 (11.0%) | 15 (8.6%) | 0.58 | |
| Sleep apnoea (n = 403) | 15 (8.2%) | 34 (15.4%) | 0.04 | |
| Depression (n = 433) | 31 (16.0%) | 36 (15.1%) | 0.90 | |
| Cognition | ||||
| CAMCOG-DS score (n = 441) | 72.0 [56.0; 84.0] | 70.5 [57.0; 83.0] | 0.83 | |
| mCRT immediate recall (n = 374) | 35.0 [28.0; 36.0] | 35.0 [31.0; 36.0] | 0.69 | |
| mCRT delayed recall (n = 369) | 11.5 [9.0; 12.0] | 11.0 [10.0; 12.0] | 0.76 | |
| Fluid biomarkers | ||||
| CSF Aβ42/Aβ40 (n = 235) | 5.3 [4.2; 7.4] e−2 | 5.9 [4.3; 7.9] e−2 | 0.54 | |
| CSF p-tau181 (n = 232) | 67.0 [29.7; 153] | 55.6 [29.3; 120] | 0.42 | |
| CSF total tau (n = 233) | 519 [280; 886] | 452 [256; 808] | 0.53 | |
| CSF NfL (n = 150) | 586 [356; 876] | 560 [353; 976] | 0.59 | |
| Plasma p-tau 181 (n = 514) | 15.1 [9.4; 24.1] | 12.9 [9.0; 22.2] | 0.09 | |
| Plasma NfL (n = 499) | 12.8 [7.3; 21.8] | 11.1 [6.8; 19.1] | 0.20 | |
| Imaging biomarkers | ||||
| Centiloid amyloid PET (n = 119) | 13.9 [1.6; 59.9] | 12.0 [1.7; 48.2] | 0.66 | |
| FDG-PET SUVR (n = 147) | 1.2 [0.9; 1.4] | 1.3 [1.1; 1.4] | 0.40 | |
| Hippocampal volume (n = 243) | 5.5 [4.9; 6.0] | 6.2 [5.5; 6.7] | <0.001 | |
| Adj hippocampal volume (n = 243) | 4.9 [4.2; 5.3] e−3 | 4.9 [4.3; 5.3] e−3 | 0.94 | |
Unless otherwise indicated, values represent n (%) or median [Quartile 1 and Quartile 3]. All fluid biomarker concentration units, except for the CSF Aβ42/40 ratio, are pg/mL. P-values refer to analyses of chi-squared tests for categorical variables and Mann–Whitney tests for continuous variables. Aβ40, amyloid β peptide 40; Aβ42, amyloid β peptide 42; CAMCOG-DS, Cambridge Cognitive Examination for Older Adults with Down Syndrome; CSF, cerebrospinal fluid; FDG, ¹18F-fluorodeoxyglucose; mCRT, modified cued recall test; NfL, neurofilament light chain; PET, positron emission tomography; p-tau181, phosphorylated tau at threonine 181; SUVR, standardized uptake value ratio; TIV, total intracranial volume.