---
title: Identify serotonin abnormalities causing pain
nct_id: NCT06008704
phase: NA
status: RECRUITING
sponsor: University Hospital, Toulouse
study_type: INTERVENTIONAL
canonical_url: "https://parkinsonspathways.com/trial/NCT06008704"
clinicaltrials_gov: "https://clinicaltrials.gov/study/NCT06008704"
last_fetched: "2026-05-10T14:05:46.244Z"
source: "Parkinson's Pathways (curated)"
---
# Identify serotonin abnormalities causing pain

**Goal (in five words):** Identify serotonin abnormalities causing pain

**Official Title:** Pathophysiology of Pain in Parkinson's Disease: Exploration of the Serotonin System in Positron Emission Tomography (PET [18F]-MPPF)

**Trial ID:** [NCT06008704](https://clinicaltrials.gov/study/NCT06008704)

## Key Facts

- **Phase:** NA
- **Status:** RECRUITING
- **Study Type:** INTERVENTIONAL
- **Sponsor:** University Hospital, Toulouse
- **Target Enrollment:** 34 participants
- **Start Date:** 2024-01-01
- **Completion Date:** 2026-09-01
- **Conditions:** Parkinson Disease
- **Interventions:** Clinical assessment, Pain characteristics assessment, MRI, Thermotest, UPDRS-III Scale, [18F]-MPPF PET scan
- **Intervention Types:** DIAGNOSTIC_TEST

## Summary For Families

The team is trying to find out whether changes in the brain's serotonin 5-HT1A system help explain chronic central pain in Parkinson's, so we can better understand why some people with PD have persistent, hard-to-treat pain. They use a PET scan with the tracer [18F]-MPPF, which binds to 5-HT1A receptors to map serotonin signaling, along with MRI, sensory thermotesting and pain and motor assessments; scans are done while participants stay on their usual, stable Parkinson medications so results reflect typical treatment. The trial is looking for people aged 40 to 80 with Parkinson's by UKPDSBB criteria, on stable anti-PD meds for at least 4 weeks, good cognition (MoCA >25) and a specified depression score (HADS-D ≥11), and either chronic central pain with average VAS ≥4 or little/no pain (VAS ≤4); people taking drugs that affect 5-HT1A, with MRI contraindications, or with disabling dyskinesias are excluded.

## Eligibility

- **Minimum age:** 40 Years
- **Maximum age:** 80 Years
- **Sex:** ALL

### Full Criteria

```
Inclusion Criteria:

* Patients with PD defined according to United Kingdom Parkinson's Disease Brain Bank (UKPDSBB) criteria
* Patients with stable anti-parkinsonian treatment for at least 4 weeks prior to inclusion
* Patients with a Montreal Cognitive Assessment (MoCA) score \> 25
* Patients with a Hospital Anxiety and Depression Scale (HADS)-D score ≥ 11
* Person affiliated or benefiting from a social security scheme.
* Free, informed and written consent signed by the participant and the investigator (at the latest on the day of inclusion and before any examination required by the research).

  • For patients with pain
* Patients with PD-related central pain defined according to the criteria of Marques et al, 2019
* Patients with chronic central pain (i.e. present for at least 3 months)
* Patients who have average pain over the previous month according to a VAS ≥ 4.

  • For patients without pain
* Patients who do not have pain defined as VAS ≤ 4, meaning that it does not interfere with daily activity.

Exclusion Criteria:

* Patients treated with second line therapy
* Patients with a history of significant psychiatric pathology according to the investigator
* Patients treated with drugs interacting with 5HT1A receptors in the previous 4 weeks
* Patients with contraindication to MRI
* Patients refusing to be informed of an abnormality discovered during brain imaging
* Patients with dyskinesias judged by the investigator to be disabling for imaging.
* Patients under guardianship or other legal protection, deprived of their liberty by judicial or administrative decision
* Pregnant woman, breastfeeding woman
```

## Locations (1)

- Centre Hospitalier Universitaire de Toulouse, Toulouse, Haute-Garonne, France _(43.6043, 1.4437)_
  - Christine Brefel-Courbon, MD, PhD — (CONTACT) — 05 61 77 94 91 — christine.brefel-courbon@univ-tlse3.fr

## Central Contacts

- Christine BREFEL-COURBON, MD PhD — (CONTACT) — 33-561777753 — Brefel-Courbon Christine <christine.brefel-courbon@univ-tlse3.fr>

---

*Canonical: https://parkinsonspathways.com/trial/NCT06008704*  
*HTML version: https://parkinsonspathways.com/trial/NCT06008704*  
*Source data: https://clinicaltrials.gov/study/NCT06008704*