Prevent Cognitive Decline in GBA-associated Parkinson's Disease

Inclusion Criteria: 1. Diagnosis of PD according to MDS-Criteria. 2. Known heterozygous severe GBA mutation (based on PD-related pathogenicity) as well as patients carrying the GBA risk variant E326K. 3. MoCA ≥ 21. 4. HY in dopaminergic ON ≤3. 5. 35 to 80 years of age at the time of signing the Informed Consent. 6. Able and willing to provide written informed consent and to comply with the study protocol according to the International Council for Harmonization (ICH) and local regulations. Exclusion Criteria: Current or Past Medical History: 1. Known pathogenic mutation carriers of the following familial PD genes: PRKN, PINK1, DJ1, LRRK2. 2. Medical history indicating a Parkinsonian syndrome other than sporadic PD (progressive supranuclear palsy, multiple system atrophy, drug-induced parkinsonism, essential tremor, primary dystonia). 3. A diagnosis of a significant CNS disease other than PD. 4. Previous, current or planned (within next 2 years) treatment with Deep Brain Stimulation (DBS) or ablation with high-intensity focused ultrasound or planned treatment with these within the next 2 years. 5. History of brain MRI scan indicative of clinically significant abnormality of prior hemorrhage or ischemic infarction \> 1 cm3, \> 3 lacunar infarctions, vascular encephalopathy with white matter lesions according to Fazekas grade III. Clinical routine brain MRI scan must be available within 2 years before Screening. 6. Concomitant disease or condition, or treatment thereof that could interfere with the conduct of the study, or that would, in the opinion of the Investigator, pose an unacceptable risk to the participant in this study or interfere with the participant's ability to comply with study procedures or abide by study restrictions, or with the ability to interpret safety data, including: 1. Autoimmune disease (however, well controlled conditions such as quiescent rheumatoid arthritis \[RAS\], controlled type I diabetes, or mild-to-moderate psoriasis not requiring systemic medications may be acceptable after discussion with Sponsor). 2. History of malignancy within 5 years prior to screening, except for appropriately treated carcinoma in situ of the cervix, non-melanoma skin carcinoma, non-metastatic prostate cancer, or Stage I uterine cancer. 3. Any active infectious disease at Screening. 4. Current, or history of, alcohol or drug abuse or other dependence (except nicotine dependence) within one year before Screening. Drug and/or alcohol abuse within 12 months prior to screening, in the investigator's judgment (except nicotine dependence, Marijuana use is not allowed \[this includes all forms of cannabidiol and tetrahydrocannabinol even if given for therapeutic use\]). 5. Any febrile illness within one week prior to first dose administration. 6. Any current psychiatric diagnosis according to Diagnostic and Statistical Manual of Mental Disorders fifth edition (DSM-5), International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) or equivalent, that may interfere with the participant's ability to perform the study and all assessments (e.g., major depression (BDI-II \>28, mental retardation, schizophrenia, bipolar disorder, etc.). Note: Mild depression, depressive mood or mild anxiety arising in the context of PD, are not exclusionary. 7. Acute suicidality, as evidenced by a) Question 5 ("Lifetime"/"Since last visit") on the Columbia- Suicide Severity Rating Scale (C-SSRS), indicating active suicidal ideation with any intent to act, at Screening or baseline (Day 1), or answering "yes" for Question 3 ("In the Past Month"/"Since last visit") on the C-SSRS, indicating active suicidal ideation with any methods (not plan) without intent to act, at Screening or baseline (Day 1) 7. The following cardiovascular conditions: 1. Myocardial infarction in the last 12 months prior to baseline. 2. Known history or documentation of uncontrolled bradycardia on more than one occasion within three months prior to baseline. 3. Resting pulse rate (PR) greater than 110. 4. Known history or documentation of uncontrolled hypertension on more than one occasion within three months prior to baseline. 5. Clinically significant cardiovascular disease including any of the following: unstable angina, decompensated congestive heart failure, clinically significant arrhythmias. 8. Clinically significant abnormalities in laboratory test results at the Screening visit, including hepatic and renal panels, complete blood count, and urinalysis, including: 1. Total bilirubin, alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \> 2 times the upper limit of normal (ULN). 2. Serum creatinine \> 1.5 times the ULN. 3. Hematocrit (Hct) less than 35% for males and less than 32% for females, or absolute neutrophil cell count of \< 1500/μL (with the exception of a documented history of a chronic benign neutropenia), or platelet cell count of \< 100,000/μL; international normalized ratio (INR) \> 1.4 4. A clinically significant abnormal thyroid-stimulating hormone (TSH) test. 5. A positive urine drug screen for a drug of abuse. For participants treated with selegiline, the amphetamine drug abuse test should be based on the results from a urine assay by liquid chromatography-mass spectrometry which is able to differentiate false positives from true positives for methamphetamine. For participants treated with benzodiazepines: A positive urine drug screen for benzodiazepines is allowed, provided that the prescription has been on a stable dosage for 90 days prior to baseline. 6. Positive result for acute or chronic infectious hepatitis B virus (HBV; \[i.e., hepatitis B surface antigen (HBsAg positive test)\]), for hepatitis C virus (HCV), or HIV 1 or 2. Successfully treated patients with HCV (undetectable HCV RNA) are eligible for enrollment. Participants who are immune due to HBV natural infection or HBV vaccination are