---
title: Detect early loss of dopamine
nct_id: NCT06456684
status: RECRUITING
sponsor: Xuanwu Hospital, Beijing
study_type: OBSERVATIONAL
canonical_url: "https://parkinsonspathways.com/trial/NCT06456684"
clinicaltrials_gov: "https://clinicaltrials.gov/study/NCT06456684"
last_fetched: "2026-05-10T14:07:18.945Z"
source: "Parkinson's Pathways (curated)"
---
# Detect early loss of dopamine

**Goal (in five words):** Detect early loss of dopamine

**Official Title:** AV133 Longitudinal Imaging Study in Patients With Early and Prodromal Parkinson's Disease

**Trial ID:** [NCT06456684](https://clinicaltrials.gov/study/NCT06456684)

## Key Facts

- **Status:** RECRUITING
- **Study Type:** OBSERVATIONAL
- **Sponsor:** Xuanwu Hospital, Beijing
- **Target Enrollment:** 76 participants
- **Start Date:** 2024-04-12
- **Completion Date:** 2026-09-30
- **Conditions:** Parkinson Disease
- **Interventions:** Fluoro[18F]promethazine
- **Intervention Types:** DIAGNOSTIC_TEST

## Summary For Families

Goal: find and track early loss of dopamine nerve terminals in people with very early or prodromal Parkinson's by detecting reductions in VMAT2, a protein that reflects how healthy dopamine storage in nerve endings is. Approach: participants undergo AV133 PET scans using Fluoro[18F]promethazine, a radioactive tracer that binds VMAT2 so clinicians can visualize and quantify dopamine terminal loss over time; this is an imaging test not a treatment, and people already on levodopa or other Parkinson medications are excluded because those drugs can alter the PET signal. Eligibility: looking for adults 30 and older with a clinical Parkinson's diagnosis within two years and Hoehn and Yahr stage I or II who show AV133 changes, plus a prodromal group generally 60 and older or 30 and older if they have certain genetic risks; everyone must be able to consent and not yet started on PD medications, and some stimulants or interfering drugs must be stopped before imaging.

## Eligibility

- **Minimum age:** 30 Years
- **Sex:** ALL

### Full Criteria

```
Inclusion Criteria:

Clinical diagnosis of Parkinson's disease： Men or women aged 30 years or older at the time of diagnosis of Parkinson's disease.

Patients must have at least two of the following: resting tremor, bradykinesia, tonicity (must have resting tremor or bradykinesia); or asymmetric resting tremor or asymmetric bradykinesia.

Time to diagnosis of Parkinson's disease at screening was 2 years or less. Hoehn \& Yahr staging stage I or II at baseline. AV133 PET scan suggestive of vesicular monoamine transporter 2 (VMAT2) deficiency.

Able to provide informed consent. Not yet started on PD medication.

Clinical diagnosis of Parkinson's disease in the prodromal phase： Subjects confirmed eligible based on existing predictive criteria Olfactory dysfunction confirmed by olfactory testing. Other predictive criteria based on general risk, such as first-degree biological relatives, known Parkinson's disease risk including RBD, or known genetic variants associated with Parkinson's disease risk (LRRK2 or GBA).

Men or women 60 years or older (or 30 years or older for subjects with SNCA or rare genetic variants such as Parkin or Pink1) AV133 deficiency as determined by visual assessment (screening PET scan) Subjects taking any of the following medications: α-methyldopa, methylphenidate, amphetamine derivatives, or modafinil must be willing and medically able to discontinue the medication for at least 5 half-lives prior to PET imaging.

Able to provide informed consent. Not yet started on PD medication.

Exclusion Criteria：

Currently taking levodopa, dopamine agonists, MAO-B inhibitors, amantadine, or other anti-Parkinson's disease medications.

Diagnosed with dementia and related cognitive impairment disorders. Received any of the following medications that may interfere with PET imaging of the dopamine transporter protein within 1 month prior to screening: antipsychotics, metoclopramide, α-methyldopa, methylphenidate, reserpine, modafinil, or amphetamine derivatives.

Current clinically significant cardiovascular disease or screening ECG abnormalities (including but not limited to QTc \> 450 ms) Currently taking medications known to cause QT prolongation; Use of an investigational drug or device within 60 days prior to baseline (dietary supplements taken outside of a clinical trial are not exclusionary, e.g., coenzyme Q10).
```

## Locations (1)

- Xuan Wu Hospital, Capital Medical University, Beijing, Beijing Municipality, China _(39.9075, 116.3972)_
  - Chen Biao, M.D., Ph.D — (CONTACT) — 13501086287 — pbchan@hotmail.com
  - Zhang Hui, Ph.D — (CONTACT) — 15811176880 — zhangxiang229@163.com

## Central Contacts

- zhang hui, Doctor — (CONTACT) — 15811176880 — zhangxiang229@163.com

---

*Canonical: https://parkinsonspathways.com/trial/NCT06456684*  
*HTML version: https://parkinsonspathways.com/trial/NCT06456684*  
*Source data: https://clinicaltrials.gov/study/NCT06456684*