Anxiety. Depression. School failure. Self-harm. Unemployment. Unplanned pregnancies. Even an increased risk of early death.

The risks and toll of suffering that can come with having attention deficit/hyperactivity disorder, or ADHD, is huge, counted annually in billions of dollars in lost productivity and health care spending and in untold frustration and failure.

Yet despite more than a century of research and thousands of published studies, ADHD — marked by distraction, forgetfulness, and impulsivity — remains largely misunderstood by the public. This is especially true when it comes to girls and women.

Over the past few decades, pediatricians, teachers, and parents have gotten a lot better at spotting ADHD in girls. In the 1990s, scientists believed it was as much as nine times as common in boys, and very few girls were diagnosed. Today's diagnosis rate has narrowed to 2.5 boys to every girl.

Still, an old problem persists. Whereas many boys with ADHD are normally more physically restless and impulsive, traits clinicians refer to as "hyperactive," many girls with the disorder may be more introverted, dreamier, and distracted — or in clinical jargon, "inattentive." In part due to these subtler symptoms, experts suspect that many girls with ADHD are still escaping notice — and missing out on treatment.

"Who gets noticed as having ADHD?" asks Stephen Hinshaw, a psychologist at the University of California, Berkeley, and a leading researcher on ADHD in girls. "You get referred if you're noticeable, if you're disrupting others. More boys than girls have aggression problems, have impulsivity problems. So girls with inattentive problems are not thought to have ADHD." Instead, he says, educators and others assume the problem is anxiety or troubles at home.

Hinshaw began studying girls with ADHD in 1997, in a federally funded project that became known as the Berkeley Girls with ADHD Longitudinal Study (B-GALS). As he and fellow researchers followed their subjects into womanhood, they found that girls with ADHD have many of the same problems as boys with the disorder, and some extra ones.

Escaping notice is just one of girls' special burdens. Girls and women, in general, engage in more "internalizing" behavior than boys, Hinshaw says, meaning they tend to take their problems out on themselves rather than others. Compared with boys who have the disorder, as well as with girls without it, girls with ADHD suffer more anxiety and depression.

Another key longitudinal study on girls, led by Harvard psychiatrist and scientist Joseph Biederman, has found that major depression in teen girls with ADHD is more than twice as common as in girls without the disorder.

The studies show that, as a group, girls with ADHD are also far more prone than boys with ADHD or other girls to self-harm, including cutting and burning themselves, and to suicide attempts. Moreover, whereas teenage boys with ADHD are more likely than girls with the disorder to abuse illegal drugs, the girls face a higher risk of becoming involved with violent partners.

Another major problem for girls with ADHD is risky sexual behavior that leads to strikingly high rates of unplanned pregnancies. Research has shown rates of more than 40 percent, versus 10 percent for young women without ADHD. In the most recent B-GALS update, published in 2019, Hinshaw and UC Berkeley psychologist Elizabeth Owens linked unplanned pregnancies to lower academic achievement earlier in life.

"Girls and women definitely blame themselves more on a daily basis," says Ellen Littman, a clinical psychologist in Mount Kisco, New York, who writes and speaks frequently about girls and women with ADHD. "If boys do badly on a test, they might say, 'What a stupid test,' while girls tend to say, 'I'm an idiot.' Girls have shame about feeling different, confused, and overwhelmed, but they're often very good at hiding it."

Attention control

ADHD is conservatively estimated to affect more than 6 million U.S. children and 10 million adults. Most with the disorder have normal intelligence — although ADHD has been associated with slightly lowered IQ scores, Hinshaw thinks this is related to the way IQ is evaluated. Some with ADHD have super-high IQ scores, he says.

Many with ADHD describe an ability to focus intensely when interested, and value their creativity. (The research on creativity, Hinshaw says, is mixed, leaving open the questions of whether ADHD helps people productively think outside the box, or whether people with the disorder are generally too disorganized to benefit from their unusual ideas.)

Some experts, including Hinshaw, think the name ADHD is not that accurate. He sees the condition as more of an inability to control attention, especially in changing situations, rather than as a deficit per se.

There's no doubt about the dark side, however, for both girls and boys. A recent study by Russell A. Barkley and Mariellen Fischer compared 131 young adults with ADHD to 71 control cases, using a life insurance actuarial model to predict estimated life expectancy. The results, published in July 2019 in the Journal of Attention, show that those with the most severe form of ADHD could see life expectancies reduced by as much as 12.7 years. In explaining that finding, Barkley, a child psychologist and researcher at Virginia Commonwealth University Medical Center, points to studies showing that children with ADHD are less careful and conscientious, more likely to follow unhealthy diets and be overweight, and more prone to suicide. Other studies have also found some increased risk of early death.

Beyond the many misperceptions about girls with ADHD, another popular myth is that ADHD is limited to children. Hinshaw, Barkley and other researchers have shown that at least half of those diagnosed in childhood continue to have symptoms of ADHD as adults. Indeed, in recent years, Hinshaw has found, women have been seeking diagnoses in nearly equal numbers as men, often after they notice signs of the strongly hereditary disorder in their children.

While watching these trends, Hinshaw and other researchers have been calling on teachers and parents to get better at identifying girls who are struggling and to develop interventions that strengthen academic performance, build self-esteem, and help girls avoid risky behaviors.

Trouble in the classroom

Despite a widespread assumption that ADHD is a late twentieth century phenomenon, it was more than two centuries ago that the Scottish physician Albert Crichton described an "unnatural or morbid sensibility of the nerves," causing extraordinary distraction. Writing in 1798, Crichton proposed that what he called "the disease of attention" could be due to heredity or accident.

As compulsory education spread throughout Europe and the United States, children who had trouble paying attention in an institutional setting were at an increasing disadvantage, notes Hinshaw.

The expansion of public schools meant that "every kid had to go to school," Hinshaw says. "And guess what? A remarkably consistent percentage of kids in Europe and the United States have particular problems focusing, sitting still, and learning to read."

With early education now mandatory in much of the world, the estimated prevalence of ADHD ranges from 5 to 7 percent in most countries, Hinshaw says. Diagnosis rates vary more widely. The United States, in which one in nine children are diagnosed, has one of the world's highest rates, a subject of major controversy.

Over the years, the disorder has had many different names, including "hyperkinetic impulse disorder" and "minimal brain dysfunction." It wasn't until 1980 that "attention deficit disorder" (ADD) — the first name to highlight distraction — was listed in the Diagnostic and Statistical Manual of Mental Disorders (DSM), the handbook relied on by mental health professionals throughout much of the world. Seven years later, a new DSM edition changed the name to "attention deficit/hyperactivity disorder," or ADHD.

ADHD is a spectrum disorder, encompassing people with mild deficits as well as those with serious impairments. Researchers today classify people as having one of three variations: hyperactive, inattentive, or a combination. Boys are more often classified as hyperactive while girls are more often described as inattentive or as a combination of inattentive and hyperactive.

The inattentive girls' symptoms may be easier to miss, but observers' biases may also lead to under-diagnoses, according to a 2018 British study comparing parents' observations with more objective measurements. The study, involving 283 diagnosed boys and girls, found that parents perceive ADHD-related behaviors differently in girls and boys, sometimes underrating hyperactivity and impulsivity in girls while exaggerating those traits in boys. "The diagnostic criteria [are] based on male behaviors," says Florence Mowlem, a health consultant who did the study as part of her doctoral work at King's College in London. "Maybe we do need slightly alternative [criteria] for females."

Read the rest of the story at Knowable Magazine. Knowable Magazine is an independent journalistic endeavor from Annual Reviews.