You can't catch attention deficit hyperactivity disorder (ADHD) but you wouldn't know that by the way diagnoses are spreading - up 10X in some countries. 

America went through this in the 1990s, when it was just ADD rather than the broader spectrum of ADHD. Then in the 2000s it was supplanted by Autism Spectrum Disorder, which replaced Autism with a set of ASD criteria so broad up to 80 percent of people are included. Fad diagnoses diminish the seriousness of the disease for families that really have it but they are good for business.

Until recently, North America tallied by far the most ADHD diagnoses, and the United States consumed 90 percent of all Ritalin, one of the most common ADHD drugs. ADHD diagnoses are still high in the U.S., but Americans account for only 75 percent of Ritalin users now.  In the U.K., ADHD diagnoses grew from less than 1 percent in the 1990s to 5 percent today. In Germany, prescription ADHD drug doses 5-folded between 1998 and 2008.  

We are beset by an economic and cultural plague, but not necessarily a medical one, says Brandeis professor Peter Conrad in Social Science and Medicine. Conrad and coauthor Meredith Bergey examined the growth of ADHD in the United Kingdom, Germany, France, Italy and Brazil.

They believe the big problem is drug companies. There is something to that, lobbyists have spurred some countries to relax marketing restrictions on stimulants and they are given a narrow window to recoup the money on products that are extremely expensive and that required daunting clinical trials before a generic comes along and makes money on their work with no effort. But the problem is that almost anyone can make a psychological diagnosis that will get translated into a pharmaceutical one. Teachers will tell parents their child has ADHD and then a parent will find a doctor who agrees. That is not the fault of drug companies, and it is hard to blame parents who don't want their child left behind - but it is an indictment of a psychology industry that has a need to over-pathologize and label all behavior. And biological psychiatry - treating psychological problems with drugs - is all the rage.

Most worrisome is that some European and South American psychologists and psychiatrists are adopting the Diagnostic and Statistical Manual (DSM-5) standards,, which even the United States National Institute of Mental Health won't use. Like with autism, the ADHD criteria were negotiated by everyone wanting their treatment speciality legitimized with insurance funding, so the standards are broader and thresholds are lower for diagnosing ADHD. Like with autism, vocal ADHD advocacy groups work closely with drug companies to promote pharmaceutical treatment.

And then there is the Internet. Like with many non-specific diseases, self-diagnosis is common and consumers will ask for specific prescription treatments 

Some websites promoting ADHD drugs offer checklists with questions like these:

• Do you fidget a lot?
• Is it hard for you to concentrate?
• Are you disorganized at work and home?
• Do you start projects and then abandon them?

"These checklists turn all kinds of different behaviors into medical problems," Conrad says. "The checklists don't distinguish what is part of the human condition and what is a disease." 

Growth in Italy and France has been slower, in part due to those countries' more restrictive pharmaceutical drug laws. However, even those nations are becoming more lax, says Conrad. In Brazil, a rising number of ADHD advocacy groups, many with close ties to the pharmaceutical industry, are raising awareness of the disorder.

"There is no pharmacological magic bullet," says Conrad. No drug can account for non-medical factors that may contribute to behavior. A fidgety student may be responding to the one-size-fits-all compulsory education system, Conrad says, not a flaw in his brain chemistry. 

ADHD continues a long history of medicalizing behaviors, especially in the U.S., Conrad says. A century ago, masturbation was considered a disease. Men and women diagnosed with masturbatory insanity were institutionalized or subjected to surgical treatment.

"I think we may look back on this time in 50 years and ask, what did we do to these kids?" Conrad says.