Swedish researchers at Lund University have discovered that pramipexole, a medication long used to treat Parkinson's disease, can significantly relieve one of depression's most crushing symptoms: the inability to feel pleasure or motivation. The finding offers hope to patients whose depression has resisted conventional antidepressants—a group for whom current treatments often fall short.
Anhedonia, the loss of joy and motivation that can accompany depression, stands apart from ordinary sadness. People with anhedonia lose interest in activities they once found meaningful or rewarding, a symptom so debilitating that it can trap patients in a cycle of withdrawal and hopelessness. "Anhedonia is one of the most debilitating symptoms of depression, and something on which current antidepressant therapies often have only a limited effect," explains Daniel Lindqvist, a researcher at Lund University and senior consultant in psychiatry at Region Skåne.
The study, published in Nature Medicine in 2026, represents an example of drug repurposing—taking an already approved medication and testing it for a different condition. For nine weeks, researchers gave some patients with marked anhedonia pramipexole as an add-on to their existing depression medication, while others received a placebo. The results were striking: those treated with pramipexole showed significantly greater improvement than the placebo group, and the benefits persisted during a six-month follow-up period for patients who continued the treatment.
To understand how the drug worked, researchers used advanced brain imaging—7 Tesla fMRI technology—to observe changes in reward-related activity in the striatum, a part of the brain crucial for processing motivation and pleasure. Filip Ventorp, a postdoctoral researcher at Lund University, notes that activity monitors revealed something equally important: "We found that pramipexole was linked to a positive effect on the brain's reward system and increased physical activity in everyday life. This supports the theory that the drug affects the dopamine system, which plays a key role in motivation and reward processing."
The safety profile proved favorable. Most patients tolerated the drug well, with few dropping out during the trial. Common side effects—sleep problems, nausea, and dizziness—were typically manageable through dose adjustment. Even those who entered the extended six-month follow-up period generally responded well, maintaining both efficacy and safety over time, a crucial finding for a condition as chronic as treatment-resistant depression.
Marie Asp, a psychiatric researcher at Lund University, acknowledges that vigilance remains necessary. "Although most participants in our study tolerated the drug well, it is important to monitor any side effects, such as impaired impulse control and daytime fatigue." Still, for patients caught in the grip of treatment-resistant depression, particularly those for whom anhedonia dominates their suffering, pramipexole offers something rare: a scientifically validated alternative when standard treatments have failed.