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

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.

Study Overview

• Status: Recruiting
• Conditions: Placebo; Naltrexone
• Intervention / Treatment: Drug: Naltrexone Hydrochloride; Drug: Placebo

• Study Type: Interventional
• Enrollment (Estimated): 210
• Phase: Early Phase 1

Contacts and Locations

• Study Contact: Name: Tristen Inagaki, PhD; Phone Number: 6195941058; Email: tinagaki@sdsu.edu

Study Locations

• United States
  • California
    • San Diego, California, United States, 92120
      • Recruiting
      • San Diego State University
      • Contact: Tristen Inagaki, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 25 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

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

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Naltrexone; 50mg naltrexone HCL once daily for seven days by mouth	Drug: Naltrexone Hydrochloride; oral naltrexone; Other Names: oral naltrexone; naltrexone pill; naltrexone; naltrexone oral tablet
Placebo Comparator: placebo; sugar pill once daily for seven days by mouth	Drug: Placebo; oral sugar pill; Other Names: sugar pill

What is the study measuring?

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

Collaborators and Investigators

• Sponsor: San Diego State University
• Collaborators: National Institute on Drug Abuse (NIDA)
• Investigators: Principal Investigator: Tristen Inagaki, PhD, San Diego State University

Study record dates

Study Major Dates

• Study Start (Actual): November 16, 2021
• Primary Completion (Estimated): April 1, 2027
• Study Completion (Estimated): July 1, 2027

Study Registration Dates

• First Submitted: July 15, 2021
• First Submitted That Met QC Criteria: August 13, 2021
• First Posted (Actual): August 16, 2021

Study Record Updates

• Last Update Posted (Actual): April 13, 2026
• Last Update Submitted That Met QC Criteria: April 8, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Heterocyclic Compounds; Heterocyclic Compounds, Fused-Ring; Carbohydrates; Alkaloids; Polycyclic Aromatic Hydrocarbons; Polycyclic Compounds; Heterocyclic Compounds, 4 or More Rings; Naloxone; Morphinans; Opiate Alkaloids; Heterocyclic Compounds, Bridged-Ring; Phenanthrenes; Naltrexone; Sugars
• Other Study ID Numbers: HS-2020-0188-SMT; R01DA052883 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Data and resources from the current study will be deposited in the Open Science Framework (OSF) and OpenNEURO.org, in accordance with the NIH Data Sharing Policy. In addition, results will be posted on the ClinicalTrials.gov website within 1 year of the study's completion date.
• IPD Sharing Time Frame: After publication of the primary findings.
• IPD Sharing Access Criteria: Researchers in both private and public sector
• IPD Sharing Supporting Information Type: ANALYTIC_CODE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No