Control of Cognition (Naltrexone, Methylphenidate, and ADHD Study (NMAS))
Condition: Healthy; Attention Deficit Hyperactivity Disorder
MeSH terms: Attention Deficit Disorder with Hyperactivity
Intervention: Methylphenidate; Naltrexone; Placebo
Intervention description: One dose 40mgs of methylphenidate one hour before fMRI scanning.; One dose 40mgs of naltrexone one hour before fMRI scanning.; One dose of placebo one hour before fMRI scanning.
Intervention MeSH terms: Naltrexone; Methylphenidate
Phase: Phase 4
Study type: Interventional
Primary purpose: Basic Science
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Enrollment: 23.0
Sex: All
Minimum age: 18 Years
Maximum age: 35 Years
Healthy volunteers: Accepts Healthy Volunteers
Keywords: Methylphenidate; Naltrexone; Placebo; Neuroimaging; Prefrontal Control Circuits; Attention Control; Motor Control; Appetitive Control

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.
    

Eligibility criteria:

        Inclusion Criteria for all study participants:

          -  Right-Handedness

        Exclusion Criteria for all study participants:

          -  Any clinically significant history of cardiac problems

          -  Any current Axis I psychiatric diagnosis as verified by the Structured Clinical
             Interview for DSM-IV (other than participants with ADHD or history of alcohol
             dependence)

          -  A previous adequate trial with methylphenidate (Ritalin) or naltrexone (ReVia)

          -  Currently taking any psychoactive medications

          -  Any clinically significant medical condition

          -  Any clinically significant neurological problem (seizures, tics, serious head injury)

          -  Contraindications to MRI (metal objects in body or claustrophobia)

          -  Currently pregnant or lactating

          -  Alcohol or substance abuse (current or in the past 2 years)

          -  Left-handedness or ambidextrous

          -  Liver or kidney disease

        Inclusion Criteria for the participants with ADHD:

          -  Currently un-medicated adults with ADHD

          -  Has met full DSM-IV-R criteria (at least six of nine symptoms)for inattentive or
             hyperactive/impulsive subtypes (or both) by age 7 as well within the past month

          -  Has described a chronic course of ADHD symptomatology from childhood to adulthood

          -  Has endorsed a moderate or severe level of impairment attributed to the ADHD symptoms