Control of Cognition (Naltrexone, Methylphenidate, and ADHD Study (NMAS))

Phase 4

Completed

Brief Summary: The goal of this research is to understand the functioning of 'regulatory circuits' in the brain. We are also interested in how the medications methylphenidate and naltrexone affect these regulatory circuits. This research study will use a scanning technique known as functional magnetic resonance imaging (fMRI) which takes a special kind of picture of the brain that enables us to "see the brain at work". Adult participants will be given a one-time dose of either methylphenidate, naltrexone,or placebo before each fMRI scan session.

The main purpose for this research is to better understand the functioning of regulatory circuits in healthy individuals and individuals with psychiatric disorders. This research may one day help us develop better treatments for these disorders.

Detailed Description: The goal of this research is to understand the functioning of 'regulatory circuits' in the brain. These are brain circuits which allow a person to regulate their attention, regulate their behavioral responses, and regulate their decision-making. We are also interested in how the medications methylphenidate and naltrexone affect these regulatory circuits. Methylphenidate is a widely-used, FDA approved medication used to treat Attention Deficit Hyperactivity Disorder (ADHD) and is also known as Ritalin. Naltrexone is an FDA approved medication used to help treat alcohol and substance abuse.

This research study will use a scanning technique known as functional magnetic resonance imaging (fMRI)which takes a special kind of picture of the brain that enables us to "see the brain at work". Adult participants will be given a one-time dose of either methylphenidate, naltrexone,or placebo before each fMRI scan session. There are three total fMRI scan sessions. Therefore, each participant will receive each possible medication/placebo only once.

Using the fMRI technique, the main purpose of this research is to better understand the functioning of regulatory circuits in healthy individuals and individuals with psychiatric disorders. This research may one day help us develop better treatments for these disorders.

Recruitment & Eligibility

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Arm && Interventions

Group	Intervention	Description
Healthy Controls	Placebo	Healthy individuals will receive a one-time, randomized dose of 40mgs of Methylphenidate, 40mgs of Naltrexone, and a placebo one hour before the fMRI scanning session.
Adult Attention-Deficit/Hyperactivity Disorder	Placebo	ADHD individuals will receive a one-time, randomized dose of 40mgs of Methylphenidate, 40mgs of Naltrexone, and a placebo one hour before the fMRI scanning session.
Healthy Controls	Methylphenidate	Healthy individuals will receive a one-time, randomized dose of 40mgs of Methylphenidate, 40mgs of Naltrexone, and a placebo one hour before the fMRI scanning session.
Healthy Controls	Naltrexone	Healthy individuals will receive a one-time, randomized dose of 40mgs of Methylphenidate, 40mgs of Naltrexone, and a placebo one hour before the fMRI scanning session.
Adult Attention-Deficit/Hyperactivity Disorder	Methylphenidate	ADHD individuals will receive a one-time, randomized dose of 40mgs of Methylphenidate, 40mgs of Naltrexone, and a placebo one hour before the fMRI scanning session.
Adult Attention-Deficit/Hyperactivity Disorder	Naltrexone	ADHD individuals will receive a one-time, randomized dose of 40mgs of Methylphenidate, 40mgs of Naltrexone, and a placebo one hour before the fMRI scanning session.

Primary Outcome Measures

Name	Time	Method
Reaction Time Variability on the Multi-Source Interference Task	2 hours	Multi-Source Interference Task is a psychological task that measures the psychological construct of cognitive control, the ability to suppress automatic response tendencies. Reaction time variability is the standard deviation of the trial to trial reaction time measured in seconds.

Secondary Outcome Measures

Name	Time	Method
Reaction Time on the Multi-Source Interference Task	Two hours	Reaction time of the Multi-Source Interference Task is measured in seconds.
Characterize the Effects of Methylphenidate and Naltrexone on Neural Circuits in Prefrontal Cortex Associated With Top-down Control.	Two hours	The effects of methylphenidate, naltrexone, and placebo on the change in BOLD (Blood Oxygen Level Dependent) signal will be characterized in the incongruent condition (cognitive regulation condition) of the MSIT (multi-source interference task) relative to the congruent condition (no regulation condition). Specifically, the summed BOLD signal in three regions--dorsal lateral prefrontal cortex, anterior insula, anterior cingulate--are measured.
Accuracy on the Multi-Source Interference Task	Two hours	Accuracy is the calculated percentage of correct responses over total trials in the Multi-Source Interference Task.