An observational study in Schizoaffective Disorder and Schizophrenia, sponsored by National Institute of Mental Health (NIMH). Completed at 1 site in United States. Open to participants aged 18 Years to 90 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-01.
Sponsored by National Institute of Mental Health (NIMH) · Observational
Background:
Objectives:
- To study the amount and distribution of two types of dopamine receptors.
Eligibility:
Design:
OBJECTIVES
Dopaminergic (DA) modulation of brain function is disturbed in several disabling psychiatric disorders and represents the target of key psychopharmacologic agents, such as neuroleptics. Schizophrenia has been considered a prototype of dysregulated DA signaling, with associated prefrontal cortex (PFC) dysfunction. Prevailing views attribute key symptoms of schizophrenia to deficient DA signaling within mesocortical DA tracts. Little is known, however, about the pre-, intra-, and post-synaptic processes that contribute to dopaminergic dysregulation. Regional cortical DA activity, critical to these processes, has been difficult to measure in patients with the available imaging techniques. The current clinical study aims to address this open issue by taking advantage of two recently developed positron emission tomography (PET) radioligands, [(11)C]NNC-112 and [(18)F]Fallypride, that bind differentially and with a higher binding potential (BP) than previous compounds to the D(1) (NNC-112) or D(2/3) (fallypride) receptors. By measuring the regional BP of these two compounds, cortical and subcortical DA receptor anomalies will be characterized in schizophrenia. Within the Clinical and Translational Neuroscience Branch (CTNB), this PET protocol is expected to add crucial information about DA receptor status to ongoing regional cerebral blood flow (rCBF), magnetic resonance imaging (MRI), magneto-encephalography (MEG) and genetic studies. It will lead to an improved understanding of the modulatory influence of DA on frontal lobe functioning and facilitate the study of how genetic polymorphisms interact with regional changes in D(1) and D(2/3) receptors to increase the risk for schizophrenia.
Some specific hypotheses to be tested are as follows:
D1 BP in frontal cortex will be affected by age, elevated in schizophrenia and inversely correlated with cognitive performance in patients and healthy controls.
Cortical D2/3 receptor BP will be affected by age and inversely correlated with performance on tests of frontal lobe function in patients and healthy controls.
Striatal D2/3 receptor BP will be altered in patients.
Polymorphisms in the catechol-O-methyl transferase (COMT), D1 and D2 genes as well as other schizophrenia risk genes will affect DA receptor BP in frontal cortex.
The ratio of cortical D1 and D2/3 receptor BPs will be affected by age and related to risk for schizophrenia, cognitive performance and polymorphisms in the COMT gene and other schizophrenia risk genes
STUDY POPULATION
It will include 100 patients with schizophrenia, schizoaffective disorder or other psychotic disorders aged 18-60, and 230 healthy controls, aged 18-90. Fifty of the controls will be matched to the patients by age and sex.
DESIGN
Dopamine D(1) and D(2/3) receptor regional binding potentials (BP) will be quantified by PET in medication-free patients and controls. High resolution T1-weighted magnetic resonance imaging (MRI) scans will be obtained for co-registration purposes. Additionally, through enrollment in other ongoing protocols (00-M-0085, 90-M-0014, 01-M-0232, 95-M-0150, 89-M-0160), rCBF, functional MRI, cognitive and genetic data will be obtained and compared with D(1) and D(2/3) receptor BP data obtained from this protocol.
OUTCOME MEASURES
Brain dopamine D(1) and D(2/3) receptor regional binding potentials measured by [[(11)C]NNC-112 and [(18)F]Fallypride PET.
1,626 studies on the registry are indexed under Psychotic Disorders; 293 are open to participants now.
This study's enrollment of 283 is above the median of 150 across 245 observational studies indexed under Psychotic Disorders.
Browse Psychotic Disorders studies →National Institute of Mental Health (NIMH) is the lead sponsor of 359 studies on the registry; 46 are open to participants now.
Of its 25 completed or terminated interventional studies of FDA-regulated products, 24 (96%) have results posted.
Counted across the registry records on this site, refreshed daily.
It will include 100 patients with schizophrenia, schizoaffective disorder or other psychotic disorders aged 18-60, and 230 healthy controls, aged 18-90.
EXCLUSION CRITERIA:
-Subjects will be excluded if they don t fit the study requirements regarding age, ability to provide informed consent, absence of significant general medical, neurological or psychiatric disorders (except the disorder object of study), or intake of substances that
interfere with central dopaminergic signaling.
healthy volunteers
Drug: PET
patients with schizophrenia, schizoaffective disorder or other psychotic disorders aged18-60
Drug: PET
Brain dopamine D1 and D2/3 receptor regional binding potentials measured by \[11C\]NNC-112 and \[18F\]Fallypride PET.
Brain dopamine D1 and D2/3 receptor regional binding potentials
Brain dopamine D1 and D2/3 receptor regional binding potentials
Time frame: ongoing
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is completed, as verified in Sep 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
National Institute of Mental Health (NIMH)