Table 2.

Subjective state questionnaire results

Subjective state questionnairePlacebo startl-DOPA startp-valuePlacebo endl-DOPA endp-value
Alert to drowsy0.
Calm to excited−0.29−0.220.42−0.36−0.060.72
Strong to feeble−0.170.680.060.060.510.96
Muzzy to clear headed0.04−0.940.12−0.60−1.120.86
Coordinated to clumsy−0.750.250.11−0.340.330.78
Lethargic to energetic−0.15−0.670.19−0.17−0.910.21
Contented to discontented−0.050.650.200.400.510.85
Troubled to tranquil−−0.71−0.320.62
Slow to quick witted−0.05−0.640.04−0.44−0.680.40
Tense to relaxed−0.04−0.540.22−0.74−0.930.44
Attentive to dreamy0.110.830.140.010.940.09
Incompetent to proficient−0.26−0.320.67−0.48−0.710.95
Happy to sad−
Antagonistic to friendly−0.09−0.240.95−0.64−1.040.26
Interested to bored0.140.400.530.520.641.00
Withdrawn to sociable0.520.410.75−0.06−0.020.88
  • Scores represent differences in ratings in a subjective state questionnaire between baseline (before placebo or l-DOPA administration) and the start of the task or the end of the task. Questions were answered by marking a point on a line and responses were converted to a 0–10 scale. We used a Wilcoxon signed-rank test and the p-values listed are not corrected for multiple comparisons. We found no evidence for an overall effect of l-DOPA on any subjective state report because no test would survive any correction for multiple comparisons. However, many such corrections might be considered too conservative. For three variables, we identified trends at the 10% significance level (uncorrected) for a difference in subjective ratings between placebo and l-DOPA. For those three cases, we then tested for a dose-dependent relationship between l-DOPA and the size of the change in subjective responses because heavier subjects may not be affected and lighter subjects would be. We found no evidence for a relationship at the 10% significance level for these three tests, and therefore found no evidence supporting a dose-dependent effect of l-DOPA on these subjective state reports.