Parkinson's Medication Shows Promise for Restoring Joy in Depression

Anhedonia — the diminished capacity to feel pleasure or motivation — is among the hardest symptoms of depression to treat. Even when other signs of depression ease, this particular symptom frequently lingers, and standard antidepressants often do little to address it directly.

A drug long prescribed for Parkinson's disease may help relieve anhedonia — the loss of pleasure and motivation — in people with depression, according to a new study led by researchers at Lund University in collaboration with psychiatric services in Region Skåne.

"Anhedonia is one of the most debilitating symptoms of depression, and something on which current antidepressant therapies often have only a limited effect," said Daniel Lindqvist, a researcher at Lund University and senior consultant in psychiatry. That gap has driven researchers to look beyond conventional treatments, turning instead to the brain systems that govern reward and motivation.

A Known Drug Tested for a New Purpose

The research employed drug repurposing — an approach that examines whether existing medications can be effective against new conditions. The drug in question, pramipexole, stimulates dopamine receptors in the brain. Because Parkinson's disease disrupts dopamine systems, the medication is routinely used to restore movement. Researchers reasoned it might similarly restore emotional responsiveness in people experiencing anhedonia. "By studying unusual conditions and treatments, we sometimes uncover solutions that were not originally intended," Lindqvist said.

The clinical trial enrolled depression patients with clear signs of anhedonia. All continued their usual medications throughout. Participants were randomly assigned to receive either pramipexole or a placebo over nine weeks, allowing researchers to attribute any observed differences to the drug itself.

By the trial's end, patients in the pramipexole group showed greater gains in their ability to experience pleasure. "Those treated with pramipexole for anhedonia showed a more pronounced improvement compared with the placebo group," Lindqvist said. Importantly, these improvements were sustained during a six-month follow-up period.

Brain Imaging and Daily Activity Findings

To examine how the drug acts on the brain, researchers used high-resolution 7 Tesla functional MRI scans focused on the brain's reward system. "We found that pramipexole was linked to a positive effect on the brain's reward system and increased physical activity in everyday life," said Filip Ventorp, a postdoctoral researcher at Lund University. The findings point to improved function in dopamine pathways as a likely mechanism.

The study also tracked participants' physical movement through wearable monitors rather than relying solely on self-reported symptoms. Patients taking pramipexole demonstrated increased activity in daily life — including basic actions such as walking and completing routine tasks — suggesting that improvements went beyond how patients felt and were reflected in actual behavior.

Safety Profile and Broader Implications

Most participants tolerated the treatment without significant difficulty, and few withdrew from the trial. Side effects, which included sleep disturbances, nausea, and dizziness, were generally mild and manageable through dose adjustments. Researchers stressed the need to monitor for daytime fatigue and changes in impulse control. "Although most participants in our study tolerated the drug well, it is important to monitor any side effects," said Marie Asp, a psychiatric researcher at Lund University.

The study is part of a wider shift in mental health research toward targeting specific symptoms rather than treating depression as a single, uniform condition. Anhedonia represents one such focal point. The findings also underscore what researchers describe as the limited reach of current antidepressants, which, while beneficial for many patients, frequently fall short of fully restoring emotional engagement.