Clinical Trial: Behavior in Children with Attention Deficit Hyperactivity Disorder and in Healthy Volunteers


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Sponsored by:	National Institute of Mental Health (NIMH)
Information provided by:	Warren G Magnuson Clinical Center (CC)

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.

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.

Official Title: A Behavioral and Functional Neuroimaging Study of Inhibitory Motor Control

Condition
Attention Deficit Hyperactivity Disorder

The inability to exert appropriate inhibitory control over one's behavior is an improtant 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 disorder (ADHD). In order to adapt the paradigm for use in fMRI studies, it is important to address two methodoligical issues: 1) the substition of a visual stop signal for the more commonly-employed auditory stop signal, and 2) the relative merits of the traditional stop task (in which the subject witholds a motor response to the "stop" signal) and a modified task, 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 these alternative stop signal paradigms 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-change tasks in control adults. The study has an event-related design and will test the hypothesest 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 activation than will go trials.

INCLUSION CRITERIA:
CONTROL SUBJECTS:
Male and female subjects in two age cohorts will be recruited: 7-16 and 18-45 years. Subjects must be free from any current or past psychopathology and be medication-free.
ADHD SUBJECTS:
Male and female subjects aged 7-16 who currently meet DSM-IV criteria for ADHD. The diagnosis will be made on the basis of a K-SADS-PL interview with the parent and a t score greater than 65 on the hyperactivity-impulsivity subscale of the Connors Teacher Scale. With the exception of symptoms and signs attributable to the ADHD, subjects must be free from any current or past psychopathology.
fMRI STUDY:
Subjects aged 18-45 years will be recruited. Subjects must be free from any current or past psychopathology, have normal physical and neurological examinations, and be medication-free.
EXCLUSION CRITERIA:
CONTROL SUBJECTS:
I.Q. less than 80; pregnancy ; ongoing medical illness; neurological disorder (including seizures); meeting past or present criteria for any diagnosis on the K-SADS-PL (children and adolescents) or SCID (adults).
ADHD SUBJECTS:
I.Q. less than 80; pregnancy; ongoing medical illness or neurological disorder other than ADHD; contraindication to discontinuing medication for 72 hours; any other psychiatric disorder that is sufficiently severe to require specific treatment, with the exception of Oppositional Defiant Disorder, and the Learning, Communication, and Elimination Disorders. Explicit exclusions include Pervasive Developmental Disorders, Tourette's syndrome, conduct disorder, and mood or anxiety disorders.
fMRI STUDY:
I.Q. less than 80; pregnancy; ongoing medical illness; neurological disorder (including seizures); meeting past or present criteria for any diagnosis on SCID; any metallic objects in the body that would constitute a contraindication to an fMRI scan.