Reward-specific Changes of the Chemical Messenger Dopamine in the Brain of Healthy and Depressed People

Summary

Major depressive disorder was shown to be associated with pathological alterations within neurotransmitter systems of the brain. Based on earlier study results, it is assumed that the neurotransmitter dopamine is relevant for several symptoms of depression, e.g., loss of interest or pleasure and lack of motivation. Thus, it is assumed that the synthesis of dopamine in the brain of depressed individuals could be impaired. The specific effect of common antidepressants on the human reward system in depression has not yet been sufficiently investigated. In particular, it is unclear whether depressed patients exhibit reward-specific changes of dopamine synthesis, and whether or not these changes can be differentially affected by diverse types of antidepressants. Neurotransmitter systems can be visualized in the brain using positron emission tomography (PET). Additionally, brain structure and function can be studied using magnetic resonance imaging (MRI). For the visualization of dopamine synthesis in the brain, the radioligand \[18F\]FDOPA can be used in PET measurements. To assess task-relevant changes of diverse radioligands and thus specific metabolic processes in the brain during specific tasks, a recently developed PET-approach can be used which has already been successfully applied in a pilot study with healthy volunteers. In the present project, 60 depressed subjects and 30 healthy controls will undergo PET/MR-imaging twice. Depressed subjects will be assigned to 1 of 2 treatment groups. 30 depressive subjects will receive bupropion, the other 30 patients will be treated with escitalopram. After a treatment period of 6 weeks, the 2nd PET measurement will be performed in all participants, aiming to detect potential reward-specific changes of dopamine synthesis. The investigators hypothesize that reward-specific changes of dopamine synthesis will be lower in depressed subjects than in healthy controls, that reward-specific changes of dopamine synthesis will be significantly higher in the bupropion group than in the escitalopram group, and that the changes of dopamine synthesis will be associated with functional changes in the brain (measured by simultaneous functional MRI scans). This will be the first study comparing the effects of escitalopram and bupropion on task-specific dopamine synthesis and thus on the human reward system. The study is expected to yield new insights for individual treatment concepts in the therapy of depression.

Conditions

• Major Depressive Disorder (MDD)

Interventions

DRUG

WELLBUTRIN SR (Bupropion HCI) Sustained-Release Tablets, 150 mg; GlaxoSmithKline

Bupropion 150 mg daily after baseline PET/MRI or MRI/MRS over 6-8 weeks

DRUG

Cipralex (escitalopram)

Escitalopram 10 mg daily after baseline PET/MRI or MRI/MRS over 6-8 weeks

Sponsors & Collaborators

• Austrian Science Fund (FWF)

  collaborator OTHER

• Medical University of Vienna

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

TRIPLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

65 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2022-12-01

Primary Completion

2026-12-31

Completion

2026-12-31

Countries

• Austria

Study Locations