Table 2.
Change in indices of cognition by group. Mean ± standard deviation is reported.
| Measure of cognition | Enrollment | 3 months | 6 months | F-test† |
|---|---|---|---|---|
| Digit symbol substitution task total score | ||||
| Adequate processing speed | 69.4 ± 11.1 | 71.5 ± 11.7 | 74.5 ± 10.7 | F = 421.7‡ |
| Below average processing speed | 42.3 ± 11.5 | 44.0 ± 11.0 | 45.9 ± 11.1 | |
| Psychomotor vigilance task lapses | ||||
| Adequate processing speed | 3.8 ± 2.6 | 3.4 ± 2.8 | 3.5 ± 2.5 | F = 23.9‡ |
| Below average processing speed | 5.8 ± 3.8 | 5.4 ± 3.4 | 5.1 ± 3.4 | |
| Trail making Test B time | ||||
| Adequate processing speed | 77.1 ± 32.8 | 74.6 ± 32.8 | 67.4 ± 31.2 | F = 88.8‡ |
| Below average processing speed | 134.6 ± 61.7 | 128.7 ± 57.3 | 127.4 ± 57.5 | |
| Probed recall memory task (out of 4) | ||||
| Adequate processing speed | 2.6 ± 1.2 | 2.7 ± 1.2 | 2.9 ± 1.2 | F = 45.5‡ |
| Below average processing speed | 1.6 ± 1.2 | 1.9 ± 1.3 | 2.0 ± 1.3 | |
| Letter number sequencing test | ||||
| Adequate processing speed | 10.4 ± 3.2 | 10.5 ± 3.4 | 10.8 ± 3.7 | F = 51.0‡ |
| Below average processing speed | 7.5 ± 3.2 | 7.7 ± 3.1 | 7.7 ± 3.2 | |
| Number of cognitive tests with impairment | ||||
| Adequate processing speed | 1.3 ± 0.7 | 1.4 ± 0.8 | 1.3 ± 0.8 | F = 29.8‡ |
| Below average processing speed | 2.0 ± 1.1 | 1.9 ± 1.1 | 1.7 ± 1.0 |
†Test of between-subjects effects; ‡ P value < .0001.