Why ADHD is so underdiagnosed in girls
Attention Deficit Hyperactivity Disorder is the mental health diagnosis of the decade it seems, with diagnoses increasing about 3 percent every year. But for all the attention it's getting these days, relatively little is known about how it affects the brain. Now, a new brain imaging study shows which structures are affected, and how they differ between males and females with the disorder.
Boys and girls are different and nowhere is that more pronounced than in the way they think. But now a new study shows that those differences extend to the way each gender manifests ADHD. While boys are still eight times more likely to get an ADHD diagnosis than girls, the gap is quickly closing — partly because doctors and researchers are recognizing that girls with ADHD show different symptoms.
Since the disorder primarily affects the frontal lobe of the brain, the part responsible for impulse control, decision-making, cognitive flexibility and planning, scientists from Baltimore did MRI scans of 30 boys and 30 girls diagnosed with ADHD. It was immediately obvious there was a difference in brain function between those with ADHD and those without, but the researchers were surprised to also find a difference in the size of the white matter — the piece of the brain that controls communication between the left and right hemispheres — between males and females with the disorder.
"The findings showed differences in the white matter microstructure between boys and girls," said study co-author Lisa Jacobson, Ph.D., a pediatric neuropsychologist at the Kennedy Krieger Institute in Baltimore. "These structural differences were associated with observed behavioral differences."
They also reported that in boys with ADHD, the differences showed up in the primary motor cortex, which controls basic motor functions, while in girls the differences appeared in the prefrontal regions of the brain, which controls motivation and ability to regulate emotions.
This may help explain the gender gap in diagnosis. Boys are more likely to be diagnosed with the "hyperactive" part of the syndrome — and this show of obvious acting out may be a primary reason more boys are labeled as ADHD — but girls are more likely to have the "distracted" form. Seeming "spacey" or forgetful isn't as disruptive as jumping off chairs or talking non-stop, leading the experts to speculate that girls are underdiagnosed. It is even more of an issue as these girls mature, with adult women being the fastest growing group being diagnosed. But no matter which way symptoms manifest or at what age women are diagnosed, the researchers say that both types can have profound effects on a person's life and self-esteem.
What this means for treatment isn't clear yet. Currently medication and behavioral treatments are the same for both men and women, but hopefully this study will lead to more individualized treatment plans and a greater recognition for the thousands of women suffering silently with ADHD every day.