Do Antipsychotic Agents Induce Supersensitivity in Humans: A Combined PET/MRI Study in Patients With Schizophrenia

September 4, 2026 updated by: Central Institute of Mental Health, Mannheim
The aim of the present study is to detect changes in the dopamine system in the brain of patients with schizophrenia, especially when pretreated with antipsychotic medication. Here, the investigators want to find out whether the treatment with these drugs can cause permanent changes in docking points (receptors) of dopamine in the brain. It will be examined whether number and response of dopamine receptors is altered, which are associated with the onset of psychotic symptoms. For this purpose, a single PET/MR measurement will be performed in all participants. In total 140 volunteers, consisting of 30 healthy volunteers, 20 first-episode, drug-naive patients with schizophrenia and 90 pretreated patients with schizophrenia will be included over a time period of three years. In addition, the influence of nicotine consumption on dopamine receptors will be invesitgated by comparing data from smoking and non-smoking patients. In clinical practice, an elevation of dopamine action caused by alterations in receptors in the brain is of most importance. This may be the reason why the treatment with antipsychotic agents does not work in some patients. In addition, a permanent elevation of dopamine action is associated with permanent brain alterations by these drugs. The result can contribute to work out valuable indications, whether it makes sense to continue a long term therapy with antipsychotic drugs in a patient. But also the in-depth understanding of the impact of nicotine on the course of therapy can help to open up possibilities for improved drug treatment.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

This project will study for the first time in humans, whether long-term treatment with antipsychotic agents, representing nowadays gold standard for patients with schizophrenia, may lead to an up regulation of dopamine D2-like receptors and associated, a supersensitivity of these receptors. The detection of such changes and the study of influencing factors (in particular smoking and type of medication) are most important for the understanding of relapse risks, development of treatment resistance and the risks for motor complications of antipsychotic pharmacotherapy. This monocentric, controlled study will include 140 participants over a time period of three years. 30 healthy volunteers, 20 first-episode, drug-naive patients with schizophrenia and 90 pretreated patients with schizophrenia will undergo a single PET/MR measurement.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
140

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria for healthy subjects:

  • Age: 18-65
  • The subject is capable to understand scope and individual consequences of the clinical study.
  • An informed consent is signed and personally dated by the subject. • No psychiatric disorder (DSM-5) currently, or in the medical history (ensured by a standardized psychiatric interview Mini International Neuropsychiatric Interview (M.I.N.I.)).

Inclusion Criteria for patients:

  • Age: 18-65
  • The criteria for schizophrenia after DSM-5 are met.
  • The subject is capable to understand scope and individual consequences of the clinical study.
  • For first-episode patients, no application of antipsychotic drugs in history. Other psychoactive substances (in particular antidepressants) are allowed if last application is at least three months ago and total Duration did not exceed three months. Benzodiazepines are allowed.
  • For medically pretreated patients: at least one year pharmacotherapy with one of the following three substances: aripiprazole or quetiapine or risperidone. A medication break of - depending on the plasma level - two days (quetiapine) up to two weeks (aripiprazole) should be clinically defensible.
  • An informed consent is signed and personally dated by the patient. For patients with legal support in addition: signature of the legal supervisor.

Exclusion criteria for patients and subjects:

  • Hypersensitivity against apomorphine or a chemically similar substance or one of the components of the applied medication.
  • Participation in other clinical trials during or within six months prior to this clinical study.
  • Medical or psychological conditions which may endanger a proper performance of the clinical trial.
  • Physical disorders which interfere according to type and severity with the planned examinations, which could influence the parameter to be investigated or could compromise the subject during the examination procedure.
  • Inability to comply with the study protocol.
  • Limited or completely repealed legal capacity.
  • For female participants: positive pregnancy test on the day of the study inclusion or on the day of the PET/MR-measurement.
  • Acute suicidality or endangerment
  • Poor general condition.
  • Participation in a study using ionising Radiation within the last five years.
  • Alcohol abuse, alcohol dependence or addiction disease / abuse of dependence-inducing substances (excluding nicotine) in the history, additional exclusion criterion for healthy subjects: regular medication intake; within the last two weeks before PET/MR-measurement no drugs at all must be taken.

Additional exclusion criterion for patients: other than the approved axis I diagnosis according to DSM-5. An axis II diagnosis is not a criterion for exclusion

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Non-Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Other: Healthy subjects
30 healthy subjects will undergo a single PET/MR-measurement.
Radiation: Single PET/MR-measurement
A single PET/MR-measurement using [18F]Fallypride with a duration of 180min. Within this measurement, the dopamine receptor agonist apomorphine is applicated.
Experimental: First-episode, drug-naive patients with schizophrenia
20 first-episode, drug-naive patients with schizophrenia will undergo a single PET/MR-measurement.
Radiation: Single PET/MR-measurement
A single PET/MR-measurement using [18F]Fallypride with a duration of 180min. Within this measurement, the dopamine receptor agonist apomorphine is applicated.
Experimental: Pretreated chronically ill patients with schizophrenia
90 pretreated chronically ill patients with schizophrenia will undergo a single PET/MR-measurement.
Radiation: Single PET/MR-measurement
A single PET/MR-measurement using [18F]Fallypride with a duration of 180min. Within this measurement, the dopamine receptor agonist apomorphine is applicated.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Dopamine D2/D3-receptor availability
Time Frame: 160 minutes
Dopamine D2/D3-receptor availability measured as binding potential (BP) using PET and blood-oxygen-level-dependant (BOLD)-response measured with fMRI.
160 minutes

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Follow-up of pretreated, chronically ill patients with schizophrenia
Time Frame: two years
In pretreated, chronically ill patients with schizophrenia, the D2/D3-receptor availability correlates with the relapse risk and the risk for the development of TD over the course of two years.
two years
D2/D3-receptor availability in first-episode, drug-naive patients with schizophrenia
Time Frame: 160 minutes
In first-episode, drug-naive patients with schizophrenia expressions of NSS and AIMS correlate significantly with striatal D2/D3-receptor availability.
160 minutes
D2/D3-receptor availability in patients with TD
Time Frame: 160 minutes
In pretreated, chronically ill patients with schizophrenia, patients with TD show a significantly higher D2/D3-receptor availability than patients without TD.
160 minutes

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Central Institute of Mental Health, Mannheim

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Gerhard Gründer, Prof. Dr., Central Institute of Mental Health, Mannheim

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
August 1, 2020

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
June 1, 2028

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
June 1, 2028

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
April 9, 2019

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 10, 2019

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
April 11, 2019

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
September 8, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 4, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
September 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 2018-09-18

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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