Could a Parkinson's drug help restore pleasure in depression?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Previous participation in RCT testing the short-term efficacy of pramipexole vs placebo (EudraCT# 2022-001563-26). * Study participants randomized to pramipexole in the RCT who wish to continue with their treatment can enrol in the study. * Study participants randomized to placebo in the RCT who continue to fulfil the inclusion criteria (and none of the exclusion criteria) after the RCT can enrol in the study. * The research subject has given informed consent to participate in the study. Additional inclusion criterion for patients receiving placebo during the RCT * Anhedonia symptoms: 3 or 4 points on ≥ 3 items of the Snaith-Hamilton Pleasure Scale (SHAPS-C). This has been adopted in previous studies as a definition of "clinically significant anhedonia". Exclusion Criteria: * Pregnancy, breastfeeding or planned pregnancy (if female). * High suicide risk according to the overall clinical assessment of the research physician. * Ongoing substance abuse (within 6 months). * Diagnosis of current psychosis. * Known diagnosis of Emotionally Unstable Personality Disorder. * Treatment under LPT. * History of impulse control disorder (including current binge-eating disorder) or a current ADHD diagnosis with hyperactivity. * Diagnosis of intellectual disability, dementia, or other circumstance that makes it difficult to understand the meaning of participating in the trial and give informed consent. * Diagnosis of renal failure or severe cardiovascular disease (specifically symptomatic heart failure NYHA Class II). Blood samples from RCT are sufficient to rule this out. * Recently started psychotherapy (within 6 weeks) or planning to start such treatment during participation in the trial. * Ongoing ECT, ketamine or rTMS treatment, excluding maintenance ECT, ketamine or rTMS (Maintenance treatment is defined as the use of ECT/ketamine/rTMS for a period exceeding 3 months after a series of ECT/ketamine/rTMS treatment in order to prevent the onset of a new episode). * Other medical conditions or other concomitant drug treatment (see section 14.5) which, in the opinion of the investigators, may affect the evaluability of the trial or conditions that increase trial risk. For example, Parkinson's disease, hepatic insufficiency, ongoing cancer not in remission for more than one year, gastric bypass surgery that affects the absorption of extended release tablets. * Known or suspected allergy to any active substance or excipient in the medicinal product included in the trial. * Participation in other treatment studies. * Other reason, as assessed by the investigator, that prevents the research subject's participation, such as the risk that the research subject is unable to complete the trial (non-compliance).