Understanding How Opioids Affect the Experiential and Neural Signatures of Social Experiences

Study Overview
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Brief Summary
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The study is a randomized, placebo-controlled design with the opioid antagonist, oral naltrexone. Following random assignment, participants will take 50mg of naltrexone or placebo once a day for 7 days. On days 1 - 7, participants complete reports of their feelings of social connection and mood in order to assess more naturalistic feelings in response to opportunities for social connection outside of the laboratory setting. Additionally, at the end of each day, they complete a physical symptoms questionnaire. On the 7th day, participants will come to the SDSU MRI scanning facility to complete tasks designed to elicit feelings of social connection in the fMRI scanner. After the scan, feelings in response to the scanner tasks will be collected.

Official Title
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Understanding How Opioids Affect the Experiential and Neural Signatures of Social Experiences

Conditions
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Naltrexone, Placebo

Intervention / Treatment
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* Drug: Naltrexone Hydrochloride
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: good health English fluency willing to provide contact information for 4-6 close others willing to provide digital photographs of 2 close others own a smartphone Exclusion Criteria: presence of medical devices, implants, or other metal objects in or on the body that cannot be removed tattooed eyeliner a body habitus prohibiting MRI scanning claustrophobia self-reported chronic mental or physical illness current and regular use of prescription medication previous history of having difficulty taking pills current use of opioid analgesics depressive symptoms above a 9 on Patient Health Questionnaire excessive alcohol use positive urine drug test body mass index (BMI) greater than 35 pregnancy or plans to become pregnant in next 6 months positive urine pregnancy test

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 25 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Naltrexone<br>50mg naltrexone HCL once daily for seven days by mouth | Drug: Naltrexone Hydrochloride<br>* oral naltrexone<br>* Other names: naltrexone oral tablet;|
| Placebo Comparator: placebo<br>sugar pill once daily for seven days by mouth | Drug: Placebo<br>* oral sugar pill<br>* Other names: sugar pill;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Daily feelings of social connection via ecological momentary assessment | State feelings of social connection outside of the lab | post-treatment, change across 7 days | 
| Bold Oxygen-level Dependent (BOLD) Activations in Prespecified ROIs | In the MRI scanner, participants read sentences written by people they know and people they do not know in a block design. In a second task they view images of people they know, those they do not know, and other emotional images. Brain activity will be measured as BOLD activity in response to stimuli from known (vs. unknown) people using functional magnetic resonance imaging (FMRI). Based on a priori hypotheses, brain activity will be masked to activity in structural regions-of- interest (ROIs) of the ventral striatum (VS), middle-insula (MI), anterior cingulate cortex (ACC) and ventromedial prefrontal cortex (VMPFC). | Day 7, approximately 60 mins after taking study drug | 
| feelings in response to neuroimaging tasks | Feelings of social connection and general positive affect in response to the neuroimaging tasks will be reported on a scale of 1 (not at all) to 7 (very) | Day 7, approximately 150 minutes after taking study drug | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| physical symptoms via daily diary | Physical symptoms previously associated with naltrexone will be assessed as well as the subjective experience of the symptoms. | end of day on days 1-7 |