Young girls suffering from attention deficit hyperactivity disorder (ADHD) may have a lot more on their plates than previously known, suggests new research published in Pediatrics.

Researchers conducted a review of existing studies looking at girls with ADHD to determine how often they were plagued by co-existing mental health problems compared to the general population. They found that about 38 percent fit the bill for a diagnosable anxiety disorder, which was nearly three time the rate seen in girls without ADHD. The girls with ADHD, mostly between the age of 8 to 13, were similarly more likely to be diagnosed with depression, oppositional defiant disorder, and conduct disorder than non-ADHD girls. While the findings weren’t surprising on their own, the authors were taken aback by how much more common behavioral problems were in the girls.

"We knew the girls with ADHD would have more problems than the girls without ADHD, but we were surprised that conduct disorder and oppositional defiant disorder were at the top of the list, not depression or anxiety," said senior author Dr. Steve Lee, a UCLA associate professor of psychology, according to Science Daily. "These conduct disorders, more than anxiety and depression, predict severe adult impairments, such as risky sexual behavior, abusive relationships, drug abuse and crime."

More specifically, 42 percent were diagnosed with oppositional defiant disorder, compared to 5 percent of non-ADHD girls; 10.3 percent were diagnosed with depression, compared to 2.9 percent of non-ADHD girls; and 12.8 percent were dealing with conduct disorder, compared to 0.8 percent of non-ADHD girls.

Both types of conduct disorders, characterized by angry, hostile and sometimes even violent behaviors, were especially surprising to see in girls, added lead author Irene Tung, a UCLA graduate student in psychology and National Science Foundation graduate research fellow, reported Science Daily.

"People tend to think of girls as having higher risk for depression and anxiety disorders, and boys as being more likely to exhibit conduct disorders, but we found that ADHD for girls substantially increases their risk for these conduct disorders,"Science Daily reported.

Traditionally, girls with ADHD have been much harder to diagnose than boys due to subtle differences in how girls manifest the condition, including when it first appears. In recent years, efforts have been made to create better ways of screening for and studying ADHD in girls.

These latest findings indicate that at least some of this research should go towards understanding how best to steer them back onto a healthy path as they age, before it’s too late.

"Kids with ADHD need structure and consistency, more than the average child; they need to know the rules and the rules need to be applied consistently," Lee said.

Behavioral therapy followed by medication are considered the first-line treatments for ADHD, according to the Centers for Disease Control And Prevention.

Source: Tung I, Li J, Meza J, et al. Patterns of Comorbidity Among Girls With ADHD: A Meta-analysis. Pediatrics. 2016.