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Patients with schizophrenia have a high risk of developing metabolic disorders and current evidence points to an overlap in mechanisms underlying psychiatric symptoms and metabolic disturbances. The main goal of this study is to investigate effects of brain insulin on dopamine signaling and energy metabolism in patients with schizophrenia experiencing their first psychotic episode (FEP). To this end, patients with schizophrenia and healthy volunteers will undergo two [11C]-(+)-PHNO positron emission (PET) scans to measure the changes in dopamine receptor availability after nasally applied insulin, as well as single proton magnetic resonance spectroscopy (1H-MRS) to assess the impact of intranasal insulin on levels of glucose and glutamate in the hippocampus.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Schizophrenia group | Experimental | 20 antipsychotic-naive patients with first episode psychosis will undergo (i) two [11C]-(+)-PHNO PET scans preceded by intranasal insulin or placebo administration in a randomized counterbalanced order, and (ii) 1H-MRS before and after intranasal insulin |
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| Healthy volunteer group | Experimental | 20 healthy volunteers will undergo (i) two [11C]-(+)-PHNO PET scans preceded by intranasal insulin or placebo administration in a randomized counterbalanced order, and (ii) 1H-MRS before and after intranasal insulin |
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| Test-retest group | Other | 6 healthy volunteers will undergo (i) two [11C]-(+)-PHNO PET scans, and (ii) 1H-MRS for test-retest purposes |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Intranasal Insulin | Drug | 160 IU intranasal insulin is administered using precision air pumps twice: 15 min prior to the PET scan and 35 min prior to the 1H-MRS scan |
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| Measure | Description | Time Frame |
|---|---|---|
| [11C]-(+)-PHNO BPND values | Dopamine D2/3 receptor availability after intranasal insulin or placebo administration | Assessed on two separate study visits within 5-12 days (scan duration: 90 min) |
| Hippocampal glucose and glutamate concentrations | Hippocampal glucose and glutamate concentrations before and after intranasal insulin administration | Assessed during a single study visit (scan duration: 40 min in total) |
| Measure | Description | Time Frame |
|---|---|---|
| Changes in blood-based parameters of energy metabolism | Changes in concentrations of selected metabolic parameters (blood glucose, insulin, c-peptide, total cholesterol, HDL, LDL, trigycerides, ketone bodies) following intranasal insulin/placebo administration, assessed by venous blood sampling | Assessed at baseline and at 15min intervals after instranasal insulin/placebo administration over a period of up to 90min |
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Inclusion Criteria:
All participants
Patients only
Exclusion Criteria:
All participants
Healthy volunteers only
Patients only
● Previous oral antipsychotic treatment for more than 2 weeks or previous treatment with antipsychotic depot preparation
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Matthaeus Willeit | Contact | +43 1 40400 | 35470 | matthaeus.willeit@meduniwien.ac.at |
| Irena Dajic | Contact | +43 1 40400 | 35470 | irena.dajic@meduniwien.ac.at |
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Medical University of Vienna | Vienna | 1090 | Austria |
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| ID | Term |
|---|---|
| D012559 | Schizophrenia |
| ID | Term |
|---|---|
| D019967 | Schizophrenia Spectrum and Other Psychotic Disorders |
| D001523 | Mental Disorders |
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| Placebo | Drug | Insulin-free dilution buffer is administered using precision air pumps 15 min prior to the PET scan |
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| Low dose insulin infusion | Drug | 2.5 mU/kg insulin in 100 ml isotonic saline is infused intravenously over 15min prior to PET scan when placebo is administered intranasally |
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| Placebo infusion | Drug | 100 ml saline is infused intravenously over 15min prior to PET scan when insulin is administered intranasally |
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| [11C] (+)-4-propyl-(+)-4-propyl-9-hydroxynaphthoxazine (PHNO) | Radiation | Each participant undergoes a 90-min [11C]-(+)-PHNO scan twice |
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| Hippocampal volumetric parameters | Whole hippocampus and hippocampal subfield volumes assessed with structural MRI | Assessed during a single study visit, at baseline (scan duration: 10min) |