Table 3.
Mean (±SE) scores of cognitive performance tests for each condition and group separately
| Variable | Group | Statistics (p values) | |||||
|---|---|---|---|---|---|---|---|
| Treatment | Chronic users | Infrequent users | Controls | Treatment × group | Treatment | Group | |
| Word Learning Test | |||||||
| Immediate recall score | Placebo | 39.5 (1.9) | 43.6 (2.2) | 46.2 (1.9) | NS | 0.003 | NS |
| Zopiclone | 35.4 (2.9) | 39.1 (2.7)a | 41.6 (2.5) | ||||
| Delayed recall | Placebo | 5.3 (0.7) | 6.8 (0.9) | 7.3 (0.8) | NS | 0.024 | NS |
| Zopiclone | 4.8 (0.8) | 5.8 (0.8) | 5.4 (0.7) | ||||
| Recognition score | Placebo | 25.4 (1.1) | 25.0 (1.3) | 25.5 (1.3) | NS | 0.014 | NS |
| Zopiclone | 24.4 (0.8) | 23.4 (1.4) | 23.5 (1.5)a | ||||
| Recognition reaction time (ms) | Placebo | 848 (32) | 785 (36) | 851 (33) | NS | 0.006 | NS |
| Zopiclone | 889 (39) | 863 (40) | 893 (34) | ||||
| Psychomotor Vigilance Task | |||||||
| Average reaction time (ms) | Placebo | 290 (13) | 290 (15) | 281 (8) | NS | NS | NS |
| Zopiclone | 288 (12) | 303 (16) | 297 (11) | ||||
| Lapses (>500 ms) | Placebo | 3.1 (1.0) | 1.7 (0.4) | 2.1 (0.6) | NS | NS | NS |
| Zopiclone | 2.6 (0.8) | 3.1 (1.0) | 2.6 (0.6) | ||||
| Critical Tracking Task | |||||||
| Average lambda (rad/s) | Placebo | 3.1 (0.2) | 2.9 (0.2) | 2.8 (0.2) | NS | 0.007 | NS |
| Zopiclone | 2.9 (0.2) | 2.7 (0.2) | 2.7 (0.1) | ||||
| Divided Attention Task | |||||||
| Average error (mm) | Placebo | 16.5 (1.5) | 18.4 (1.1) | 19.8 (1.3) | NS | <0.001 | NS |
| Zopiclone | 18.9 (1.2)a | 20.5 (1.3)a | 21.4 (1.1) | ||||
| Reaction time (ms) | Placebo | 2,052 (87) | 1,971 (75) | 1,941 (81) | NS | 0.034 | NS |
| Zopiclone | 2,038 (65) | 2,086 (71)a | 2,140 (93) | ||||
| Stop Signal Task | |||||||
| Hits (#) | Placebo | 241 (3) | 246 (1) | 247 (1) | NS | 0.016 | NS |
| Zopiclone | 240 (3) | 245 (1) | 245 (2) | ||||
| Go reaction time (ms) | Placebo | 437 (19) | 432 (19) | 438 (13) | NS | 0.001 | NS |
| Zopiclone | 442 (18) | 452 (20)a | 459 (15)a | ||||
| Stop reaction time (ms) | Placebo | 181 (7) | 184 (8) | 202 (10) | .034 | <0.001 | 0.016 |
| Zopiclone | 184 (9)b | 197 (8)a | 229 (9)a | ||||
NS = no significant effect
aSignificantly different from placebo within group (p < 0.05)
bSignificantly different from control group (p < 0.05)