Figure 1.

Study design. Part a shows the study design with the cross‐over randomization of the tryptophan interventions (ATD, acute tryptophan depletion; BAL, balanced; ATL, acute tryptophan loading), the final number of participants for each intervention and session (N = 85) and the number of participants in each possible order of interventions. Part B shows the timeline of a study session. The mixture was prepared 1 hr before the participant arrived. At T0, the first blood sample was taken as a baseline measure of tryptophan plasma concentrations, followed by the ingestion of the mixture and mood and behavioral assessments. Additional blood samples were taken 1, 3, and 6 hr after the ingestion of the mixture. The fMRI session was carried out 3 hr after the drink [Color figure can be viewed at http://wileyonlinelibrary.com]