Psilocybin Therapy for Depression in Parkinson's Disease

Inclusion Criteria:

* Age 40 to 80
* Comfortable speaking and writing in English
* Have neurologist-diagnosed idiopathic Parkinson's disease (PD), Hoehn and Yahr stages 1 to 3 during an "on" phase (time when medication/DBS for parkinsonian motor feature, including bradykinesia and rigidity is in effect)
* Currently experiencing depressive symptoms
* Able to attend all in-person visits at UCSF as well as virtual visits
* Have a primary care provider, neurologist, or psychiatrist who is actively managing or coordinating

Exclusion Criteria:

* Psychotic symptoms involving loss of insight
* Significant cognitive impairment
* Regular use of medications that may have problematic interactions with psilocybin
* A health condition that makes this study unsafe or unfeasible, determined by study physicians