Table 3. Result of neurocognitive tests and driving tests.
| Neurocognitive tests | placebo group(N = 50) | caffeine group(N = 50) | p-value | |
|---|---|---|---|---|
| SDC | Correct Responses b | 66.1 ± 9.7 | 67.2 ± 11.2 | 0.74 |
| Errors b | 1.3 ± 1.4 | 1.5 ± 1.8 | 0.58 | |
| ST | Simple Reaction Time b | 320.3 ± 45.3 | 308.0 ± 40.2 | 0.09 |
| Complex Reaction Time Correct b | 620.1 ± 68.3 | 614.1 ± 70.9 | 0.65 | |
| Stroop Reaction Time Correct a | 704.7 ± 81.0 | 694.8 ± 89.3 | 0.56 | |
| Stroop commission Errors b | 1.0 ± 1.2 | 0.9 ± 0.8 | 0.73 | |
| SAT | Correct Responses b | 52.2 ± 6.4 | 55.0 ± 5.7 | 0.03 |
| Errors b | 3.7 ± 2.6 | 2.5 ± 2.0 | 0.02 | |
| Correct Reaction Time a | 1000.7 ± 127.6 | 959.5 ± 133.2 | 0.12 | |
| Four Part CPT | Part 1 | |||
| Average Correct Response Time b | 334.2 ± 40.0 | 324.4 ± 46.2 | 0.09 | |
| Part 2 | ||||
| Correct Responses b | 6.0 ± 0.1 | 6.0 ± 0.0 | 0.32 | |
| Average Correct Response Time a | 412.1 ± 50.3 | 409.2 ± 46.8 | 0.77 | |
| Incorrect Responses b | 0.0 ± 0.2 | 0.1 ± 0.4 | 0.39 | |
| Average Incorrect Response Time b | 18.3 ± 91.7 | 32.8 ± 113.7 | 0.41 | |
| Omission Errors b | 0.0 ± 0.1 | 0.0 ± 0 | 0.32 | |
| Part 3 | ||||
| Correct Responses b | 15.8 ± 0.5 | 15.8 ± 0.5 | 1.00 | |
| Average Correct Response Time b | 473.1 ± 64.9 | 454.7 ± 63.6 | 0.15 | |
| Incorrect Responses b | 0.1 ± 0.2 | 0.0 ± 0.1 | 0.31 | |
| Average Incorrect Response Time b | 28.3 ± 121.6 | 11.0 ± 77.6 | 0.31 | |
| Omission Errors b | 0.2 ± 0.5 | 0.2 ± 0.5 | 1.00 | |
| Part 4 | ||||
| Correct Responses b | 13.1 ± 2.2 | 13.4 ± 2.3 | 0.36 | |
| Average Correct Response Time a | 640.5 ± 134.6 | 619.2 ± 135.3 | 0.43 | |
| Incorrect Responses b | 1.0 ± 1.2 | 1.1 ± 1.1 | 0.35 | |
| Average Incorrect Response Time b | 455.8 ± 444.8 | 560.4 ± 453.7 | 0.39 | |
| Omission Errors b | 2.9 ± 2.2 | 2.6 ± 2.3 | 0.36 | |
| Driving tests | placebo group(N = 50) | caffeine group(N = 50) | p-value | |
| SDLP (m) a | 0.87 ± 0.27 | 0.89 ± 0.25 | 0.75 | |
| BRT (sec) a | 0.89 ± 0.12 | 0.84 ± 0.08 | 0.048 | |
Abbreviations: SDC = Symbol Digit Coding Test, ST = Stroop Test, SAT = Shifting Attention Test, FPCPT = Four Part Continuous Performance Test, BRT = the brake reaction time, SDLP = the standard deviation of the lateral position.
The data are the mean ± standard deviation for skewed variables.
a: via non-paired t-tests.
b: Mann-Whitney U test.