Girls are closing one gender gap we don’t want: diagnoses of Attention deficit hyperactivity disorder (ADHD). Between 2003 and 2011, parents reported an increase of ADHD diagnoses of 55% for girls, compared to 40% for boys, according to a 2015 study in the Journal of Clinical Psychiatry.

And yet girls continue to be misdiagnosed in spades, with alarming consequences, Dr. Ellen Littman, clinical psychologist and co-author of Understanding Girls with AD/HD, tells Quartz. “The outcomes for girls are horrendously negative compared to boys,” she says.

ADHD materializes dramatically differently in girls.

“Anxiety and depression turn into low self-esteem and self-loathing, and the risk for self-harm and suicide attempts is four-to-five times that of girls without ADHD,” 2012 research shows.

“This is not about having trouble with their homework,” Littman says.

Unlike boys, many of whom show hyperactivity, girls’ symptoms veer more toward inattentiveness and disorganization. Girls tend to develop ADHD later than boys. They frequently mask it in an attempt to conform to society’s expectation that they be on the ball and organized. And while some ADHD symptoms can become less intense for boys after they pass through puberty, for many girls, it gets worse.

“I think we have a lost generation of women who are diagnosed with ADHD later in life, who have had to manage the condition on their own and deal with it on their own for the majority of their lives,” Michelle Frank, a clinical psychologist and ADHD expert, tells Quartz. “The diagnosis is a blessing and a curse: it’s a great relief, but they wonder what could have been different if they had only known.”

ADHD is harder to recognize in girls

In Understanding Girls with AD/HD, Littman and her co-authors explain that ADHD was first diagnosed in young, white boys, with a key indicator being hyperactivity. As a result, guidelines were written around how it manifests in boys, and research is almost exclusively focused on boys (1% is specific to girls, Littman says).

It also materializes much later in girls, which was problematic when the American Psychiatric Association’s diagnosis criteria called for symptoms to be visible by age 7. It recently changed the age (pdf) to 12, allowing more girls to be captured.

Dr. Patricia Quinn, one of Littman’s co-authors on the book and a pediatrician in Washington, DC, who founded the National Center For Girls and Women With ADHD, told HuffPo Parents that girls’ symptoms include:

a tendency toward daydreaming

trouble following instructions

making careless mistakes on homework and tests.

ADHD is a chronic neurobiological disorder which affects the brain structurally and chemically, as well as the ways in which various parts of the brain communicate with one another. It is highly heritable, says Frank.

Pressure to perform means many girls internalize their symptoms—disorganization or carelessness—as personal flaws rather than medical issues to be treated through medicine and therapy.

Girls with ADHD are significantly more likely to experience major depression, anxiety, and eating disorders than girls without. “They tend to have few friendships,” Littman says. “As a result of their low self-esteem, they often choose unhealthy relationships in which they may accept punitive criticism and or abuse.”

Teachers and parents often miss the warning signs because feeling disorganized or unfocused often leads to depression and anxiety. Failing to properly diagnose the condition, girls miss out on critical academic services and accommodations, as well as therapy and medication. Many girls end up misdiagnosed and treated with anti-anxiety or depression drugs, some of which exacerbate the effects of ADHD.

The numbers

Progress is being made. Not long ago, the ratio of diagnosed boys vs. girls with attention-deficit hyperactivity disorder was 10 to 1. Today, it is somewhere between 4 to 1 and 2 to 1, Littman says.

According to the Journal of Clinical Psychiatry study, ADHD affected 7.3% of girls in 2011, compared to 16.5% for boys. Oddly, as awareness grows about ADHD in girls, there is evidence that boys are being wildly over-diagnosed with ADHD, including 17-year-old-boys who want extra time to complete the SAT for college applications.

“There’s no question it is both under-diagnosed and over-diagnosed,” Littman says.

This is not to say that millions of boys and men don’t have ADHD or suffer from the consequences of it.

“It’s important to remember that while we have to focus on increasing awareness and services to girls and women, boys and men are also profoundly affected by ADHD. We have a long way to go in addressing the immense stigma and gross misunderstanding that surrounds this diagnosis,” says Frank.

But Littman says the myths around ADHD and girls remain pervasive and she is deluged daily by people who are seeking help. “Girls are being told still by pediatricians and primary care doctors that ‘you are a girl, you can’t get ADD.” (ADHD includes the symptom of physical hyperactivity while ADD does not).

Women and ADHD

Other pernicious myths around ADHD include the perception that adult women, including successful professionals, can’t have ADHD.

Just the opposite. When the structure of school and college make way for the anarchy of balancing work and maybe having children, keeping ADHD at bay becomes harder.

Littman works with, and has studied, the impact of ADHD on high-IQ men and women, many of whom spent years masking their symptoms with their high abilities. As she tries to target if ADHD is the issue, she asks whether they are “constantly in a state of being overwhelmed and frantic about coping with day-to-day basic things?” Most burst into tears. “These are the people least likely to be acknowledged and because of the shame of feeling smart, they don’t feel they are entitled to help.”

Not surprisingly, she says, there are as many female as male patients in adult clinics. One study of ADHD medication showed women were the fast-growing population. Between 2008 and 2012, the number of Americans using medication to treat ADHD rose 36%; among women aged 26 to 34, the figure rose 85%.

Frank says even those who were diagnosed, though perhaps late, face serious longer-term consequences. “You can treat ADHD, you can get support and strategies, but the self-esteem challenges are going to be left over and you have to work at that for a lot longer.”

Personal stories have helped to raise awareness about the fact that girls can have ADHD, and that it presents itself differently. Maria Yagoda wrote in the Atlantic about being diagnosed as a junior at Yale:

My peers were also confused, and rather certain my psychiatrist was misguided. “Of course you don’t have ADHD. You’re smart,” a friend told me, definitively, before switching to the far more compelling topic: medication.“So are you going to take Adderall and become super skinny?” “Are you going to sell it?” “Are you going to snort it?” The answer, clearly, was no.

“Medication is certainly not a cure-all, but when paired with the awareness granted by a diagnosis, it has rendered my symptoms more bearable—less unknown, less shameful,” she wrote.