Treat each non-motor PD domain with disease-specific pharmacology rather than generic agents, and use quetiapine rather than typical antipsychotics when psychosis needs treating to minimize motor worsening. Recognize that depression affects up to forty percent of patients and may precede motor symptoms, which means antidepressant therapy may be indicated even before a formal PD diagnosis.

MPTP is a potent dopaminergic neurotoxin; For dementia, you can use donepezil or rivastigmine; When dealing with depression, selective serotonin reuptake inhibitors or tricyclics are appropriate choices; Because it replicates the core pathology of Parkinson's so accurately, it's actually the primary compound used to test almost all new therapies in animal models; If psychosis emerges, medications like quetiapine, olanzapine, or ziprasidone can be used, though you have to exercise a lot of caution with them in Parkinson's disease cases