Influence of Dopaminergic Blockade on Stress Responses, Motivation and Emotional Reactivity in Humans.
Condition: Healthy Participants
Study type: Interventional

Summary: 
      The study aims to identify whether partial blockade of human dopamine signaling with
      antipsychotic drugs affects human stress responses, motivation and emotion. 84 healthy adult
      participants are planned to complete the study protocol.

      Therefore three experiments are planned:

      Experiment 1: Influence of amisulpride on human stress responses. Experiment 2: Influence of
      amisulpride on motivated effort. Experiment 3: Influence of amisulpride on emotion.
    

Detailed description: 
      The study is a double blind, placebo controlled, randomized trial with two groups. One group
      will be receiving placebo (PG) and the other group will receive 300 mg amisulpride (VG). All
      participants are planned to complete all three experiments sequentially after drug/placebo
      intake.

      In experiment 1 we want to test whether a medium single dosage of amisulpride (VG) changes
      human stress responses compared to the PG. Therefore test subjects take the medication /
      placebo and wait for peak plasma levels. Afterwards they undergo a standardized stress test
      (MAST procedure,e.g. Shilton et al., 2017) where they submerge their non-dominant hand in
      cold water and have to do mental arithmetic tasks. We collect ECG, cortisol and skin
      conductance data as well as subjective measures of the stress response.

      In experiment 2 that is done after completion of experiment 1 the aim is testing whether the
      VG compared to the PG has an altered motivated effort. Therefore so called effort based
      paradigms (Reddy et al., 2015) are used. In these paradigms participants are given the option
      between an easy and effortless way of solving a trial that is reinforced with a small
      monetary reward or a harder and effortful way of trial solving that is rewarded higher. We
      measure how often the VG versus the PG will take the easy, low reward option over the hard,
      high reward option.

      In experiment 3 and after the completion of experiment to the aim is it to test whether the
      mean intensity of visually evoked emotions in the VG is changed compared to the PG. Therefore
      we use a stimulus set (15 positive images, 15 negative images, 15 neutral images) out of the
      International Affective Picture System images to evoke emotions and plan to analyze data like
      in positivity offset research (detailed description in: Strauss et al, 2017).
    

Intervention name(s): Amisulpride 300 MG; Placebo oral capsule
Intervention type(s): Drug; Drug
Intervention description(s): A single dose of 300 mg amisulpride that looks identical to placebo control capsules.; A placebo capsule with no inert pharmacological effect. Looks identical to the amisulpride capsules.
Intervention MeSH terms: Amisulpride
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Basic Science
Keywords: dopamine antagonists; dopamine blockade; psychophysiological stress response; Maastricht acute stress test (MAST); effort based paradigms; positivity offset theory; international affective picture system (IAPS)