Attention Deficit Hyperactivity Disorder (ADHD) is the most common behavioral disorder in childhood, affecting 3-5% of children between the ages of 7 and 17. Family studies suggest that there is a genetic component to ADHD. Scientists believe that it is a complex disorder in which two or more genes may be involved.
Potentially eligible families will be asked to give written consent to participate and will be asked to complete questionnaires for each member in the family. In addition, an interview will be administered to the parent of minors enrolled in the study to determine their eligibility for being in the study. This screening tool is computerized and will take approximately 45 minutes to administer per child.
Once screenings are completed, a blood collection kit will be sent to the family to take to their local medical care provider, have blood samples drawn and sent to NIH. There is no cost to the family to participate. We would like to enroll entire families, with both parents and all children.
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Attention Deficit Hyperactivity Disorder (ADHD) is a prevalent neuropsychiatric disorder affecting 5% of children worldwide. A study of the hypothesis that Attention Deficit
Hyperactivity Disorder (ADHD) is a genetically influenced brain disorder has been undertaken using a two armed approach: 1) Isolated population analysis from a large, extended pedigree study done in Colombia, South America in a population isolate called the Paisa have been studied for the last 7 years; and a recently added second isolated in USA from Amish population at Lancaster, Co Pennsylvania; with different background and environmental influences, and 2) a U.S. based study of nuclear families with at least one affected child and at least one sibling (either affected or unaffected), and their parents. Following careful phenotyping, DNA from blood samples from these two genetically different groups will be analyzed through a genomewide scan for linkage and positional candidate approach to search for genes associated with ADHD. In addition comparison of genetic-environment interactions will be done on these two different populations. Genetic influence are to modulate biological aspects in cognition and behavioral manifestations. The prefrontal cortex and its connections is known to play a very important role in the processing of emotions and impulsivity. It is considered the primary biological component of a brain circuit that would explain the main clinical characteristics present in ADHD phenotype. Measurement of brain metabolites in this region may be very useful in phenotyping ADHD. Thus, after identification of specific genotype implicated in ADHD risk in the Colombian population, in a subset of already recruited individuals, phenotyping will include proton magnetic resonance spectroscopy (H MRS) to detect biochemical phenotypes which may be correlated with genetic markers for ADHD. Additional analysis for potential genetic-environment interactions will be done to compare isolated populations in different environments. Identification of a biological marker to be used to support and confirm clinical diagnosis is highly desirable.