Psilocybin, a natural compound found in certain mushrooms, has shown promise in treating depression and anxiety. UC San Francisco researchers wanted to know if it could be used to help Parkinson’s patients who often experience debilitating mood dysfunction in addition to their motor symptoms and don’t respond well to antidepressants or other medications.

The results were surprising.

Not only did participants tolerate the drug without serious side effects or worsening symptoms, which is what the pilot study was designed to test, they also experienced clinically significant improvements in mood, cognition, and motor function that lasted for weeks after the drug was out of their systems.