Table 1. Data from questionnaires, neuropsychological assessment (NPA), mood, blood pressure and urine metabolites.
| Measure | Screening | Placebo | Tyrosine | Drug effect | |
|---|---|---|---|---|---|
|
Exclusion criteria |
HADS | 3.7 (2.6) | N/A | N/A | N/A |
| MMSE | 29.1 (1.3) | N/A | N/A | N/A | |
| NLV—IQ estimate | 114.9 (8.6) | N/A | N/A | N/A | |
| Effort questionnaire | NCS | 50.7 (11.8) | N/A | N/A | N/A |
| Dopamine proxies | BIS-11 | 58.2 (6.3) | N/A | N/A | N/A |
| Digit span | N/A | 13.3 (3.3)* | 12.7 (3.7) | t(27) = 1.5, p = 0.145 | |
| General neuropsychological assessment | Story recall—immed | N/A | 9.8 (2.8) | 10.6 (3.2) | t(28) = -1.2, p = 0.254 |
| Story recall—delay | 9.3 (2.7) | 9.7 (3.0) | t(28) = -0.6, p = 0.535 | ||
| Stroop effect (sec) | N/A | 84.3 (48.6)* | 87.7 (73.7)** | t(26) = -0.2, p = 0.815 | |
| Verbal fluency, total | N/A | 46.3 (9.4) | 44.0 (10.1)* | t(27) = 1.2, p = 0.246 | |
| Box completion, min | N/A | 90.0 (33.7)* | 82.5 (19.4) | t(27) = 1.2, p = 0.248 | |
| Digit cancellation, min | N/A | 246.8 (31.4)** | 250.8 (38.9)* | t(25) = -0.8, p = 0.433 | |
| Mood (T1-T0) | Calmness | N/A | -0.5 (1.7) | -0.9 (1.9)* | t(27) = 0.7, p = 0.485 |
| Contentedness | N/A | -0.6 (1.4) | -0.7 (1.3)* | t(27) = 0.1, p = 0.888 | |
| Alertness | N/A | -0.2 (1.1) | -0.1 (1.0)* | t(27) = -0.6, p = 0.584 | |
| Total | N/A | -0.4 (1.0) | -0.4 (1.0)* | t(27) = -0.1, p = 0.906 | |
| Blood pressure (T1-T0) | Systolic | N/A | 4.1 (8.6) | -0.6 (6.7) | t(28) = 2.1, p = 0.041 |
| Diastolic | N/A | -2.7 (5.1) | -2.3 (4.4) | t(28) = -0.3, p = 0.740 | |
| Heart rate | N/A | 0.1 (5.1) | -0.2 (3.4) | t(28) = 0.3, p = 0.768 | |
| Metabolites in urine (T1-T0) | DOPAC | N/A | -0.03 (0.3) | 0.2 (0.4) | t(28) = -3.0, p = 0.006 |
| HVA | N/A | 0.6 (0.8) | 0.5 (0.7) | t(28) = 0.9, p = 0.370 | |
| VMA | N/A | 0.3 (0.2) | 0.3 (0.2) | t(28) = 2.1, p = 0.048 | |
| MOPEG | N/A | 0.2 (0.1) | 0.2 (0.2) | t(28) = 1.5, p = 0.157 |
Measures are acquired during screening or testing days (see §2.2). Data represent mean (standard deviation) and when administered in both experimental sessions, results of paired-sample t-tests are presented to assess intervention effects. For the NLV-score and BIS-11 score, data points of 3 and 1 participant(s) were missing, respectively.