Study tests if cannabis Self-Medication theory holds up in schizophrenia

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: Groups 1-3 Participants with schizophrenia and a cannabis use disorder 1. Ages 18 - 55 years 2. Diagnosis of schizophrenia 3. Diagnosis of cannabis abuse or dependence 4. Use of cannabis within the month prior to screening 5. Willing to remain abstinent for the 14 days before the baseline assessments and throughout the two scans. 6. Psychiatrically stable 7. Treated with a stable dose of an antipsychotic medication (except clozapine) for the past month 8. Not seeking treatment for their cannabis use disorder. Group 4 - Control participants with schizophrenia 1. Ages 18 - 55 years 2. Diagnosis of schizophrenia 3. Willing to remain abstinent as described above 4. Psychiatrically stable 5. Treated with a stable dose of an antipsychotic medication (except clozapine) for the past month Groups 5-7 - Control participants with cannabis use disorder 1. Ages 18 - 55 years 2. Diagnosis of cannabis abuse or dependence 3. Use of cannabis within the month prior to screening 4. Willing to remain abstinent as described above 5. Not seeking treatment for their cannabis use disorder. Group 8 - Healthy control participants 1. Ages 18 - 55 years 2. Willing to remain abstinent as described above Exclusion criteria: Groups 1-3 with schizophrenia and a cannabis use disorder 1. Positive symptoms of psychosis (\> 4 \[moderate\]) on any item of the Positive and Negative Syndrome Scale psychosis subscale (once abstinent) except for the hallucination item. We will exclude for a rating \> 5 for this item. 2. Cocaine/stimulant use disorder 3. Pharmacological treatment for addiction 4. Mental retardation 5. History of head injury 6. Metal objects within the body that would contraindicate and MRI 7. Pregnancy or currently nursing 8. Uncontrolled medical condition 9. Taking clozapine 10. Any condition that would contraindicate use of cannabis or dronabinol. 11. History of a seizure disorder Group 4 - Control participants with schizophrenia 1. Positive symptoms of psychosis (\> 4 \[moderate\]) on any item of the Positive and Negative Syndrome Scale psychosis subscale (once abstinent) except for the hallucination item. We will exclude for a rating \> 5 for this item. 2. Any history of a substance use disorder other than nicotine 3. Pharmacological treatment for addiction 4. Mental retardation 5. History of head injury 6. Metal objects within the body that would contraindicate and MRI 7. Pregnancy or currently nursing 8. Uncontrolled medical condition 9. Taking clozapine Groups 5-7 - Control participants with cannabis use disorder 1. Axis I psychiatric diagnosis other than a cannabis use disorder 2. Taking any psychotropic medication 3. Pharmacological treatment for addiction 4. Mental retardation 5. History of head injury 6. Metal objects within the body that would contraindicate and MRI 7. Pregnancy or currently nursing 8. Uncontrolled medical condition 9. History of a seizure disorder Group 8 - Healthy control participants 1. Any Axis I psychiatric diagnosis 2. Taking any psychotropic medication 3. Pharmacological treatment for addiction 4. Mental retardation 5. History of head injury 6. Metal objects within the body that would contraindicate and MRI 7. Pregnancy or currently nursing 8. Uncontrolled medical condition 9. Current tobacco smokers