Studying the effects of dietary body weight-adjusted acute tryptophan depletion on punishment-
related behavioral inhibition
Sammanfattning
Background: Alterations in serotonergic (5-HT) neurotransmission are thought to play a decisive
role in
affective disorders and impulse control.
Objective: This study aims to reproduce and extend previous findings on the effects of acute
tryptophan
depletion (ATD) and subsequently diminished central 5-HT synthesis in a reinforced categorization
task
using a refined body weightadjusted depletion protocol.
Design: Twenty-four young healthy adults (12 females, mean age [SD]25.3 [2.1] years) were
subjected to a
double-blind within-subject crossover design. Each subject was administered both an ATD challenge
and a
balanced amino acid load (BAL) in two separate sessions in randomized order. Punishment-related
behavioral
inhibition was assessed using a forced choice go/no-go task that incorporated a variable payoff
schedule.
Results: Administration of ATD resulted in significant reductions in TRP measured in peripheral blood
samples, indicating reductions of TRP influx across the bloodbrain barrier and related brain 5-HT
synthesis.
Overall accuracy and response time performance were improved afterATDadministration. The ability
to adjust
behavioral responses to aversive outcome magnitudes and behavioral adjustments following error
contingent
punishment remained intact after decreased brain 5-HT synthesis. A previously observed
dissociation effect of
ATD on punishment-induced inhibition was not observed.
Conclusions: Our results suggest that neurodietary challenges with ATD MojaDe have no
detrimental effects
on task performance and punishment-related inhibition in healthy adults.