When Peter Coyne’s 6-year-old son was diagnosed with ADHD 12 years ago, Coyne, 53, hardly knew what the disorder was. So he decided to read up on it.

“Suddenly I thought, ‘oh my God,’ this is what I’ve had my entire life,” says Coyne, a designer at a public relations firm. He flashed back to his younger years in school. He never thought he was stupid, but as classes progressively required more reading and attention, he suffered.

“It was frustrating. I used to think, maybe I don’t try hard enough. Maybe I don’t care. Maybe I’m lazy,” says Coyne. He scheduled an appointment with a psychiatrist, and Coyne got his own ADHD diagnosis the same year as his son. He finally had an answer for why he was the way he was. It was a relief.

The number of adults taking ADHD drugs rose by more 50% between 2008 and 2012, according to a report out this week from pharmacy management company Express Scripts. In 2001, 0.5% of adults ages 20 to 44 were on ADHD drugs, says Dr. David Muzina, vice president of specialist practice at Express Scripts. It crossed the 1% mark for men in 2004, and for women in 2005, and has been steadily rising ever since.

Parents educating themselves for the past decade about a problem that afflicts more and more children has led to greater awareness about the disorder. “What commonly brings someone in is they see their child being evaluated and recognize symptoms in themselves,” says Dr. Len Adler, the director of adult ADHD at New York University’s School of Medicine.

But diagnosing adults isn’t the same as diagnosing children—it’s harder. Since adults in general deal with a greater cognitive load than kids, there’s a fine line when it comes to distinguishing stress overload from legitimate ADHD symptoms. According to the DSM V, adults and children are assessed based on long list of symptoms for both inattentiveness and hyperactivity. Kids must meet six symptoms in each category for a period of at least six months, while adults need only meet five in each for the same time period—since adults tend to learn to cope and lose some of the more obvious symptoms with age. Some of the symptoms sound like your average overworked adult: difficulty with organization, easily distracted, unable to sustain attention, fidgeting, talking too much, interrupts often.

Most importantly, though, adults need to show that the roots of their disease took hold in childhood. “The consensus is that you cannot develop ADHD as an adult. You must have had symptoms in childhood,” says Dr. Joseph Austerman, a children’s psychiatry and psychology clinician at Cleveland Clinic. But ascertaining that is inherently problematic, since reporting often comes from the distracted adult in question. Significant others or parents are sometimes consulted, but the amount of information physicians can assess for adult patients is limited compared to that for children. Research has found that, among adults with ADHD, only 11% are diagnosed and treated.

The alarming rise in medication among children and adults has skeptics questioning the accuracy of so many diagnoses. Many also point to the successful marketing push from big pharma, which in 2012 saw profits nearing $9 billion for stimulant medications, compared to $1.7 billion just a decade ago, according to a report from The New York Times. And that’s from what has been predominantly a kids market. Online quizzes from ADHD advocacy groups can also prompt adults to seek help. “There’s no denying there’s a strong possibility that these numbers speak to clinicians’ proclivity to easily prescribe these medications to adults who are asking for them,” says Dr. Muzina.

While there may be growing cases of questionable ADHD diagnoses, for those who do have the disorder, it’s a relieving answer to a confusing and frustrating childhood. Men, who are more commonly diagnosed with ADHD, struggle more with holding down jobs and relationships.

“People at my age, we learn to adapt,” says Coyne. “It’s not like I can’t sit in my chair anymore. Now, I am just distracted.”

Dr. Muzina estimates that ADHD drug use in adults will grow by 25% over the next five years. But the chicken or egg question prevails. “The part that we are concerned about is how much of this drug use is related to over-diagnosis and over-treatment of symptoms that aren’t really a condition,” Dr. Muzina says.

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