Kennedy Krieger Researchers Exploring the Effects of ADHD on Girls

February 13, 2004
Condition likely nearly as prevalent in girls as boys; study aims to find better methods for diagnosis, treatment in girls

Baltimore- In the United States, an estimated five out of 100 school children have attention deficit hyperactivity disorder, which many experts believe is a neurobiological disorder that inhibits children - usually boys - from being able to control their behavior. A study at Kennedy Krieger Institute is now probing how ADHD uniquely affects girls - and experts hypothesize that it is probably much more common in girls than people think.

Using anatomic magnetic resonance imaging technology, researchers at Kennedy Krieger can see how brain regions are affected differently in girls who have ADHD compared to boys. This has enormous implications for diagnosis and treatment; the study is likely to show that standard methods for diagnosing and treating ADHD in boys are generally ineffective for use with girls.

Anecdotal evidence from parents, teachers and others suggests that ADHD manifests itself differently in girls than in boys, but little scientific research has been done to confirm this. Where boys with ADHD frequently have trouble sitting still, keeping their hands to themselves and behaving in socially appropriate ways, girls with the disorder seem to have the most difficulty with tasks involving organization and memory: completing a complex assignment, following test instructions, remembering to bring home school books. Girls with ADHD also tend to be overly talkative and bossy.

Girls with ADHD usually are not identified until later in adolescence, if at all, when poor school performance has already lead to low self-esteem and increased detrimental behavior. Not surprisingly, girls with ADHD demonstrate significantly higher rates of depression and drug use than boys with the condition.

"Girls tend to remain cosmetically' well-behaved in school, but their disorder becomes more obvious in the tween' years as a greater burden is placed on them in terms of personal responsibility," says Dr. Martha Bridge Denckla, principal investigator of the study. "The behavior standard is set so much higher for girls in general; they can have many more social problems than boys. Getting them treatment earlier could ward off the crises many of them experience in adolescence."

This study hopes to confirm the differences in symptoms between the sexes, as well as draw a connection between the symptoms and the composition of the brain regions responsible for those skills. With the support of a five-year, $1.8 million grant from the National Institutes of Health, Dr. Denckla and her colleagues are recruiting 200 girls and boys, both with and without ADHD. The children will complete tasks assessing those skills often impaired by ADHD, and undergo clinical tests and MRI scans.

"I want to document the distinctive features of ADHD in girls and discover which parts of their brain circuitry are involved," Dr. Denckla says.

Scientists will compare the results of clinical tests with the MRI scans of the children's brains, and expect to find that girls with ADHD have smaller brain volumes in certain regions responsible for organization and working memory. Boys also tend to have smaller volumes in these regions, as well as in areas responsible for impulse control.

Discovering the unique ways in which ADHD affects girls will lead to new methods for earlier diagnosis and the development of programs tailored to the specific needs of girls with the disorder.

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