Carbidopa

This clinical study is being conducted to learn more about a new imaging drug called \[18F\]MK-0947, which is designed to help doctors see changes in the brain related to Parkinson's disease (PD). PD is a condition that affects movement, balance, and thinking. The drug works with a type of scan called PET (Positron Emission Tomography) to show areas of the brain where a protein called α-synuclein builds up. This buildup is linked to PD and other brain disorders. The main goal of this study is to find out if \[18F\]MK-0947 is safe for people and if it works well to show α-synuclein in the brain. The study will also look at how the drug moves through the body and how much radiation it gives off. Researchers hope this information will help develop better tools for diagnosing PD and tracking how it changes over time. Who can join? Adults who have PD or who are healthy may be able to take part. Participants will have screening tests to make sure they qualify. What does participation involve? People in the study will have PET scans, blood tests, and other safety checks. Some participants will also have an MRI scan. The study is divided into two parts: Part 1 looks at how the drug works in the brain of PD patients and healthy elderly participants, and Part 2 measures radiation levels in healthy participants. Why is this important? There is currently no cure for PD, and better imaging tools could help researchers develop new treatments. By joining this study, participants will help advance research that may improve care for people with PD and similar conditions in the future.

The purpose of this study is to investigate the use of ultra-low, anti-inflammatory doses of radiation therapy (RT) for the treatment of Parkinson's Disease (PD). In this study, the TrueBeam LINAC utilizes a linear accelerator (LINAC) for the delivery of radiation therapy. Dynamic conformal arc (DCA) therapy will be used to deliver a total of five (5) once-a-day radiation treatments (RT) using DaT-SPECT (Dopamine Transporter-Single-Photon Emission Computed Tomography) and MRI imaging to guide radiation treatment planning.

This study aims to evaluate the efficacy of community-based early detection and targeted interventions, including stem cell therapy and wearable non-invasive brain-computer interface (BCI) devices, for Mild Cognitive Impairment (MCI) in adults aged 55 years and older residing in U.S. urban and suburban communities. Primary objectives include assessing improvements in MCI detection rates, cognitive outcomes, and progression delay compared to standard care.

The purpose of this study is to evaluate the efficacy, safety, and pharmacokinetics (PK) of prasinezumab compared with placebo in participants with early-stage Parkinson's disease (PD) on stable symptomatic monotherapy with levodopa.

The goal of this clinical trial is to learn if cognitive cueing (eg., prompting individuals to think about taking big-long steps while walking), either as a stand- alone intervention or combined with a personalized gait training video, can improve gait (walking), mobility, and balance confidence for individuals with Parkinson's Disease. The main questions it aims to answer are: 1. Does focusing on cognitive cues while walking improve gait, mobility, and balance confidence for individuals with Parkinson's Disease? 2. Does incorporating a personalized gait training video alongside cognitive cueing lead to amplified improvements in gait, mobility, and balance confidence for individuals with Parkinson's Disease? Researchers will compare how gait, mobility, balance confidence and quality of life change over time for participants when they practice walking with and without a cognitive cue alone, and when they practice with using a personalized gait training video. The researchers are also interested in how participation in this trial will affect quality of life and conscious attention to gait. Participants will * Complete walking trials on an instrumented mat that records data on their walking ability. These trials will be undertaken without a cognitive cue and while participants mentally rehearse a series of 3 cognitive cues (Take big long steps; Walk heel-toe; Stand up straight). * Be informed about which of the 3 cues best improved their walking and will receive a personalized gait training video for at home practice. * Complete online surveys that ask questions about their Parkinson's Disease, mobility, balance confidence quality of life and conscious attention to gait. * Visit the research facility 3 to 4 times during the study to have their gait (walking), mobility, balance confidence, quality of life and conscious attention to gait assessed and reassessed. * Practice both with and without their personalized video at home and keep a diary to record their practice sessions * Participate in a brief interview to discuss their experiences with the training and their perceptions of the effectiveness of cognitive cues and video-recorded feedback

The Goal of this study is to evaluate the safety, tolerability, and clinical responses following implantation of DSP-1083. Study enrolls both male and female patients in 2 cohorts. This study will be held in approximately 5-8 study sites in United States

The investigators propose a Phase I single surgical-center, double-blinded randomized parallel clinical trial involving bilateral autologous peripheral nerve tissue (PNT) delivery into the NBM or the alternate target also affecting cognition in this population, the substantia nigra (SN), to address "repair cell" support of these areas. Twenty-four participants with idiopathic Parkinson's Disease (PD) who have selected, qualified and agreed to receive as standard of care deep brain stimulation (DBS) will be enrolled and randomly allocated to receive bilateral PNT deployment to either the NBM or SN at the time of DBS surgery. Participants will be allocated equally among both assignments over the course of three years (8 Year 1, 10 Year 2, 6 Year 3). Participants will be evaluated for neurocognitive, motoric function, activities of daily living, and quality of life at enrollment before surgery, two-weeks after surgery, and 6, 12, and 24 months after surgery.

The purpose of this study is to evaluate the safety, tolerability, and PK/PD of LY3962681 in healthy volunteers and patients with Parkinson's disease. The study will be comprised of two parts, the Single Ascending Dose (SAD) study and the Multiple Ascending Doses (MAD) study. During the SAD portion of the study, healthy volunteers will receive a single dose of LY3962681 or placebo (artificial cerebrospinal fluid (aCSF), no active drug) given into the spinal fluid. During the MAD portion of the study, patients with Parkinson's disease will receive two doses of either LY3962681 or placebo (aCSF) administered into the spinal fluid. * The treatment period in the SAD study will be 1 day. The treatment period in the MAD study will be 2 days, 12 to 24 weeks apart. * The follow-up period in the SAD study will be up to 52 weeks. The follow-up period in the MAD study will be up to 52 weeks post Dose 2.

To evaluate the safety and efficacy of transplantation of human induced pluripotent stem cell-derived dopaminergic progenitors, CT1-DAP001, into the corpus striatum in patients with Parkinson's disease

Investigation of tenapanor as a potential treatment for synucleinopathy-associated constipation

Parkinson's disease (PD) is a devastating illness that has a growing impact on Veterans. One of the most disabling symptoms is depression, which is common in PD and linked to poor quality of life and higher risk of suicide. Unfortunately, there is a lack of effective treatments for depression in PD. Ketamine, which has rapid and potent antidepressant effects, is a potential option but has not been tested in Veterans with PD. Studies in rodents show that ketamine may not only improve depression in PD, it may target two of the underlying drivers of the disease: (1) reduced neuroplasticity, or the brain's ability to adapt and remodel itself; and (2) elevated inflammation. The investigators are conducting a randomized, placebo-controlled study to examine if a dose of intravenous (IV) ketamine improves depression in Veterans with PD. The investigators will also examine ketamine's effects on neuroplasticity and inflammation, which will help us understand how ketamine works in PD and if it can be a useful treatment for Veterans with the disease. This study will lay groundwork for a larger clinical trial across multiple VA sites.

The overall goal of the proposed research is to evaluate the use of \[11C\]SY08 as a PET radiotracer for aggregated alpha synuclein (αS) in individuals with Parkinson's disease (PD), Multiple system atrophy (MSA), Dementia with Lewy Bodies (DLB) and healthy controls. The purpose of this study is to evaluate the use of \[11C\]SY08 as a PET radiotracer for αS fibrils in individuals with PD, MSA, DLB and healthy controls. The specific aims of the current study are: 1. To determine brain uptake, distribution, and kinetics of \[11C\]SY08 in healthy individuals. 2. To determine brain uptake, distribution, and kinetics of \[11C\]SY08 in patients with alpha synuclein aggregates in the brain, including PD, DLB and MSA. 3. To determine human dosimetry of \[11C\]SY08 in healthy individuals An intravenous bolus injection of \[11C\]SY08 will be administered per subject for brain PET imaging.