Table 1. Descriptive statistics of sequenced ARIC participants.
| Characteristic | African Americans (N = 406) | European Americans (N = 1,008) |
|---|---|---|
| % Female | 67.7% | 53.4% |
| % APOE ε4 carriers | 44.1% | 33.0% |
| Time between amyloid measurements (in years) | ||
| Mean (SD) | 18 (1) | 18 (1) |
| Range | 16–20 | 16–20 |
| Age (in years) | ||
| Visit 3 Mean (SD) | 59 (5) | 60 (5) |
| Range | 50–71 | 50–70 |
| Visit 5 Mean (SD) | 77 (5) | 77 (5) |
| Range | 67–89 | 67–90 |
| Plasma aβ42 (in pg/ml) | ||
| Visit 3 Mean (SD) | 26.69 (9.30) | 30.06 (9.64) |
| Interquartile Interval | 20.10–31.80 | 23.20–36.34 |
| Visit 5 Mean (SD) | 33.57 (12.06) | 38.45 (11.23) |
| Interquartile Interval | 25.50–39.70 | 30.70–45.20 |
| Fold-change Mean (SD) | 1.30 (0.49) | 1.31 (0.41) |
| Interquartile Interval | 1.04–1.44 | 1.06–1.47 |
| aβ42:aβ40 ratio | ||
| Visit 3 Mean (SD) | 0.20 (0.11) | 0.19 (0.07) |
| Interquartile Interval | 0.15–0.22 | 0.15–0.23 |
| Visit 5 Mean (SD) | 0.17 (0.07) | 0.17 (0.06) |
| Interquartile Interval | 0.13–0.20 | 0.13–0.19 |
| Fold-change Mean (SD) | 0.95 (0.33) | 0.93 (0.31) |
| Interquartile Interval | 0.75–1.11 | 0.73–1.08 |
NOTE: SD = Standard deviation. The amyloid measures were non-normal, thus the interquartile interval conveyed the amyloid values in the 25th to 75th percentile.