Clinical Trial: Study of Attention Deficit/Hyperactivity Disorder Using Transcranial Magnetic Stimulation
Study Status: Completed
Recruit Status: Completed
Study Type: Observational
Official Title: Cortical Correlates of Subtle Motor Signs in Attention-Deficit/Hyperactivity Disorder and Healthy Controls
Brief Summary:
Attention deficit/hyperactivity disorder is a condition characterized by a decreased attention span, hyperactivity, and/or impulsiveness inappropriate for a certain age.
Typically, young children have what are known as subtle neurological signs. These are involuntary movements of one part of the body that occur while the child is making a voluntary movement of another part of the body. This is referred to as synkinesis, or overflow movements. These overflow movements disappear during normal development and are usually gone by the age of 10. However, in children with ADHD these overflow movements tend to be more intense and last long after the age of 10. This leads researchers to believe there is an abnormality in the maturation and development of the brain areas associated with motor activity in children with ADHD.
Transcranial Magnetic Stimulation (TMS) is a non-invasive technique that gives information about brain function. It is very useful when studying areas of the nervous system related to motor activity (motor cortex, corticospinal tract, and corpus callosum). A magnetic signal given from a special instrument held close to the patient's head stimulates a small area of the brain that controls a few muscles (for example, the muscles that control one finger). Doctors put electrodes (small pieces of metal taped to areas of the body) over the muscle to measure the electrical activity the muscle produces when it makes a movement. When the magnetic signal activates those muscles the electrodes pick up and record the electrical activity of the movement that the muscles make in response to the magnetic signal.
Researchers will study normal children and those diagnosed with ADHD using TMS to find out if the clinical abnormalities of ADHD are associated with a delay or abnormal
Detailed Summary:
Subtle neurological signs (synkinesis and mirror movements) are present in normal children up until 9 or 10 years of age. In addition, speed of repetitive and sequential movements increases from 5 to 8 years of age at which time children perform these movements at close to adult speeds. Based on clinical studies of both normal children and of children with corticospinal tract lesions, it has been postulated that these subtle motor signs reflect neurodevelopmental immaturity of the intracortical and interhemispheric inhibitory systems and that their disappearance occurs as a result of maturation.
The presence of subtle neurological signs can accurately distinguish children with attention-deficit/hyperactivity disorder (ADHD) from healthy controls. The increased intensity of these neurological signs in younger age groups and their persistence beyond the age of 9 years suggest that children with ADHD may have delayed or abnormal neuromaturational development; in particular, development of the inhibitory systems of the motor cortex. This is in concert with the theories of cognitive abnormalities seen in these children where behavioral studies indicate that children with ADHD have most difficulty in executive function tests that look specifically at motor inhibition.
Transcranial magnetic stimulation (TMS) is a non-invasive tool which gives information about cortical function. It is particularly useful in the study of the motor cortex and its connections via the corticospinal tract and the corpus callosum. A single suprathreshold stimulus to the motor cortex produces a motor evoked potential (MEP) and inhibition of ongoing muscle activity in ipsilateral and contralateral target muscles. TMS studies have demonstrated differences in both the velocity of central motor conduction, and the ability to evoke motor inhibition when comp
Sponsor: National Institute of Neurological Disorders and Stroke (NINDS)
Current Primary Outcome:
Original Primary Outcome:
Current Secondary Outcome:
Original Secondary Outcome:
Information By: National Institutes of Health Clinical Center (CC)
Dates:
Date Received: November 3, 1999
Date Started: January 1999
Date Completion: February 2004
Last Updated: March 3, 2008
Last Verified: February 2004
