Behavior in Children With Attention Deficit Hyperactivity Disorder and in Healthy Volunteers
Condition: Attention Deficit Hyperactivity Disorder
MeSH terms: Hyperkinesis; Attention Deficit Disorder with Hyperactivity
Study type: Observational

Summary: 
      The purpose of this study is to determine how the brain controls motor activity in children
      with attention deficit hyperactivity disorder (ADHD).

      The inability to control one s behavior is an important symptom of many psychiatric
      illnesses. The stop signal paradigm which involves withholding a motor response to a go
      signal, has proved useful in assessing uncontrolled behavior in children with ADHD and other
      disorders. This study will use a stop signal paradigm in order to evaluate the ability of
      children with and without ADHD to control their motor behavior. A magnetic resonance imaging
      (MRI) scan will be used to study how the brain works during specific activities.

      This study will evaluate the stop signal paradigm in three groups of people: healthy
      children, children with ADHD, and healthy adults. This study comprises two sub-studies: a
      behavioral study in which participants perform simple activities and an MRI study.

      Participants will be asked to stop any over-the-counter medication 5 days before entering the
      behavioral or MRI study. Children with ADHD will be asked to stop taking medication for ADHD
      72 hours before the study. All participants will have a medical history and a psychiatric
      evaluation (for children, both parents and children provide information for the assessment).
      Participants in the MRI study will also have physical examinations and blood and urine tests.
      All children will undergo intelligence tests; and those with ADHD will have tests to confirm
      the diagnosis. The parents of child participants will complete an autism screening
      questionnaire.
    

Detailed description: 
      The inability to exert appropriate inhibitory control over one's behavior is an important
      symptom of many psychiatric illnesses. The stop signal paradigm, which involves withholding a
      prepotent motor response to a signal, has proved useful in assessing this deficit in children
      with a range of disorders, particularly attention deficit hyperactivity disorder (ADHD). In
      order to adapt the paradigm for use in fMRI studies, it is important to address two
      methodological issues: 1) the substitution of a visual stop signal for the more
      commonly-employed auditory stop signal, and 2) the fact that, on the traditional stop task
      (in which the subject withholds a motor response to the stop signal), correct trials do not
      involve a motor response whereas incorrect trials do. The latter problem can be addressed
      using the stop-change task (in which the subject executes alternative motor responses to the
      stop and go signals). The first aim of this protocol is to compare behavioral data from the
      stop and stop-change tasks in control adults, control children, and children with ADHD. These
      data will be used to test the hypotheses that, on each of these paradigms, children with ADHD
      will show an inhibitory deficit compared to control children, and control children will show
      an inhibitory deficit compared to control adults. The second aim of the protocol is to
      conduct a pilot fMRI study of the stop and stop-change tasks in control adults. The study has
      an event-related design and will test the hypotheses that ventral prefrontal activation will
      be greater during successful than unsuccessful stop (or stop-change) trials, and that stop
      and stop-change trials will be associated with more anterior cingulate and right inferior
      frontal activation than will go trials.
    

Observational model: Cohort
Time perspective: Other
Keywords: Stop Task; Functional (BOLD) MRI; Developmental; Inhibitory Control; Attention Deficit Hyperactivity Disorder; ADHD; Impulsivity; Healthy Volunteer; Normal Volunteer; HV