An interventional study of Précurseur de la dopamine and antagoniste D2 in Neurosciences, sponsored by Hôpital le Vinatier. Recruiting at 1 site in France. Open to participants aged 18 Years to 45 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-06-12.
Sponsored by Hôpital le Vinatier · Not applicable, Interventional, and Basic science
Reality-monitoring characterizes the ability to determine whether information was perceived in the environment or only imagined . Impaired reality-monitoring abilities have been associated with hallucinations in patients with schizophrenia and patients with Parkinson's disease.
The investigators hypothesize a link between dopaminergic (DA) transmission and reality-monitoring.
This hypothesis is based on several studies in the literature: 1) DA transmission anomalies are observed in both schizophrenia and Parkinson's disease; 2) DA agonists may induce hallucination; 3) DA antagonists reduce hallucinations and improve reality-monitoring abilities in patients with schizophrenia. In addition, also suggesting a link between mesocorticolimbic connectivity, subcortical DA transmission and reality-monitoring, The investigators have shown that fronto-temporal transcranial Direct Current Stimulation (tDCS) leads:
Hôpital le Vinatier is the lead sponsor of 106 studies on the registry; 41 are open to participants now.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Short tests of memory and thinking, each scored out of 30. Lower scores suggest more difficulty; criteria give a range, either to include people with memory problems or to leave them out.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
MMSE and MoCA
Short tests of memory and thinking, each scored out of 30. Lower scores suggest more difficulty; criteria give a range, either to include people with memory problems or to leave them out.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Excipients
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
In the first condition, volunteers will receive a dopamine (DA) precursor (L-dopa, 100mg). L-dopa will be combined with a dose of an Aromatic amino acid decarboxylase inhibitor (Benserazide) 25mg to multiplicate its bioavailability and with a dose of domperidone 10mg (peripheral antagonist of DA) to minimize the risk of side effects.
Other: Précurseur de la dopamine
In the second condition, volunteers will receive a D2 antagonist (Sulpiride, 800mg)
Other: antagoniste D2
In the third condition, volunteers will receive a placebo (lactose)
Other: PLACEBO
In the first condition, volunteers will receive a 100mg dose of L-dopa, 25mg dose of Aromatic amino acid decarboxylase inhibitors (Benserazide) and 10mg dose of Domperidone. In the second condition, volunteers will receive Sulpiride 800mg. In the third condition, volunteers will receive placebo Reality-monitoring performances will be evaluated with a standardized task. Working-memory will be evaluated with the n-back task. Self-monitoring performances will be observed during a speech production experiment in which speakers monitor their auditory feedback while speaking. Speech Bayesian reasoning: This task is a home-made task investigating the influence of prior on speech processing. Subjects will be required to identify speech in ambiguous auditory stimuli. Visual Bayesian reasoning: This task investigates the influence of prior on visual processing. Subjects will be required to recognize morph between faces and house.
In the second condition, volunteers will receive Sulpiride 800 mg
In the third condition, volunteers will receive placebo
Reality-monitoring performance
Measured with a behavioral task developed, validated and used in investigators lab. During the memory retrieval phase, 48 words will be presented, including the 32 words presented during encoding as well as 16 new words. Subjects will be required to identify whether each word was previously heard, imagined or new. Three words lists will be used and assigned randomly depending on the substance condition (L-dopa, Sulpiride, placebo). Each verbal list will include 16 items with the "imagine hear" encoding condition and 16 items with the "listen" encoding condition. A single measure including two variables of interest will account for the main evaluation criteria: * The average conditional source-identification measure (ACSIM) which represents the overall ability to correctly retrieve the source, conditional on that item was recognized as already presented. * The source misattributions,the number of confusions between heard and imagined events.
Time frame: One month
Reaction times at the reality-monitoring task and scores of subjective confidence rating for reality-monitoring responses
Regarding reality-monitoring, a single test in which investigators will also measure the reaction times at the reality-monitoring task and scores of subjective confidence rating for reality-monitoring responses. The variable of interest will be the number of high-confident incorrect source-recognition responses. Investigators finally measure the vividness of each "imagined" or "listened" word with Visual Analogue Scales (VAS) from 0 to 100.
Time frame: One month
Other cognitive tasks
In the same test investigators will measure the number of correct/incorrect responses and reaction times at the n-back working memory task. * The effect of dopamine modulation on the ability the ability to determine our speech as self-generated will be measured with a self-monitoring task. Investigators measure the magnitude of a voice peak response reflecting the feeling of agency. * The effect of dopamine modulation on perception will be evaluated with the performances measured during 2 home-made Bayesian reasoning tasks, evaluating speech processing and visual processing, respectively.
Time frame: One month
Plan to share: No
No publications or documents are linked to this record.
Started Jan 2024 (actual). Primary completion is estimated for Jan 2027, 36 months after the start.
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