Boys are more likely than girls to be diagnosed with attention deficit hyperactivity disorder, a condition characterized by difficulty paying attention and controlling behavior. But new research suggests that the consequences for girls with the disorder can be particularly serious.
Girls with ADHD have high rates of self-injury and attempts of suicide during their teenage years, a study published in the Journal of Consulting and Clinical Psychology found.
"We were floored by these findings," said study author Stephen P. Hinshaw, a professor of psychology at the University of California, Berkeley. "This rate of self-destructive behavior was shocking, and it shows that the longterm consequences of ADHD are not trivial."
According to the Centers for Disease Control and Prevention, approximately 5 million children aged 3 to 17 years had ADHD in 2010. According to the 2010 survey, 11 percent of boys had received an ADHD diagnosis, compared to about 6 percent of girls.
Hinshaw and his colleagues began looking at ADHD in females in the late 1990s, studying a group of 148 girls in the San Francisco area with the disorder who were between the ages of 6 and 12. For the just-published study, the researchers followed-up with 95 percent of the girls in that original group, now between the ages of 17 and 24. They checked on the girls' behavior and academic progress, comparing them to a control group of women of the same age, without ADHD.
More than half of the girls with a sub-type of ADHD characterized by inattention as well as hyperactivity or impulsivity had engaged in some form of self-harm, such as cutting, burning or pulling out chunks of their hair.
In addition, approximately one-fifth of the girls with that sub-type of ADHD had attempted suicide. But girls whose ADHD was defined solely by inattention showed no increase in rates of self-injury or risk of suicide.
"This research emphasizes that parents of ADHD girls need to continue to be vigilant about their daughters' well-being even after they graduate from high school," said Steven Meyers, a professor of psychology at Roosevelt University and a clinical psychologist based in Chicago, who did not work on the study. "As children enter young adulthood and go off to college or find their first job, an early ADHD diagnosis can serve as a marker for risk and adversity."
Mental health experts do not yet have a grasp on what causes girls with ADHD to harm themselves. However, Hinshaw offered a few hypotheses.
ADHD and depression commonly occur together, he said. Though at least 40 percent of the study participants who were diagnosed with ADHD as children no longer met formal criteria for the disorder as they got older, many continued to struggle socially and academically.
"[These girls have] probably spent years being behind the eight ball -- being targeted by peers and falling farther and farther behind academically," Hinshaw said. "Girls are internalizing this, and they're literally destroying themselves."
Another possible factor is impulsivity, which some research has linked to suicidal behavior, he said.
"It's that feeling that 'I've got pain that is unbearable, and I've got to act now,'" Hinshaw explained.
But Meyers, the Roosevelt University professor, cautioned that the new study does not "tease apart" whether girls who harmed themselves had additional mental health disorders during young adulthood. Future research must examine whether the higher rates of self-harm are primarily in girls who have ADHD and co-existing depression, he said.
Over the 10-year period, many of the girls received treatment for their ADHD, including medication and counseling, although it was often sporadic.
Hinshaw said that the study highlights the need for parents and mental health providers to take ADHD in girls seriously and to make sure they get thorough assessments.
"Too many clinicians and doctors think that this is a boy's disorder and that girls don't get it," Hinshaw said. "Our study shows that when they do, the consequences are very serious."