The rise of A.D.H.D. diagnoses and prescriptions for stimulants over the years coincided with a remarkably successful two-decade campaign by pharmaceutical companies to publicize the syndrome and promote the pills to doctors, educators and parents. With the children’s market booming, the industry is now employing similar marketing techniques as it focuses on adult A.D.H.D., which could become even more profitable.

Few dispute that classic A.D.H.D., historically estimated to affect 5 percent of children, is a legitimate disability that impedes success at school, work and personal life. Medication often assuages the severe impulsiveness and inability to concentrate, allowing a person’s underlying drive and intelligence to emerge.

But even some of the field’s longtime advocates say the zeal to find and treat every A.D.H.D. child has led to too many people with scant symptoms receiving the diagnosis and medication. The disorder is now the second most frequent long-term diagnosis made in children, narrowly trailing asthma, according to a New York Times analysis of C.D.C. data.

Behind that growth has been drug company marketing that has stretched the image of classic A.D.H.D. to include relatively normal behavior like carelessness and impatience, and has often overstated the pills’ benefits. Advertising on television and in popular magazines like People and Good Housekeeping has cast common childhood forgetfulness and poor grades as grounds for medication that, among other benefits, can result in “schoolwork that matches his intelligence” and ease family tension.