Study to Evaluate DNL201 in Subjects With Parkinson's Disease

Key Inclusion Criteria: * Body mass index (BMI) between 18 and 35.0 kg/m2, inclusive * Clinical diagnosis of Parkinson's disease meeting UK Brain Bank criteria and H\&Y Stage I, II, or III. * sPD subgroup without a LRRK2 mutation; PD LRRK2 subgroup with LRRK2 mutation * Screening dopamine transporter (DAT) SPECT scan with a DAT deficit consistent with Parkinson's disease * Able to hold Parkinson's disease medications 8 hours (overnight) prior to specific study assessments Key Exclusion Criteria: * Any history of clinically significant asthma, chronic obstructive pulmonary disease, or emphysema within 5 years of screening, or other clinically significant pulmonary disease within 6 months of screening * Abnormal Vitals including Respiratory Rate, Body Temperature, and Blood Pressure * Pulmonary Function Tests (PFTs) (FVC \<60% predicted, FEV1 \<50% predicted, FEV1:FVC ratio \<0.6, DLCO \<70% predicted) * Clinically significant neurologic disorder other than Parkinson's disease, including history of stroke, cognitive impairment, seizure within 5 years of screening, or head trauma with loss of consciousness within 6 months of screening * Montreal Cognitive Assessment (MoCA) score of \<24 at screening