At the Peace in Medicine Healing Center in Sebastopol, the wares on display include dried marijuana - featuring brands like Kryptonite, Voodoo Daddy and Train Wreck - and medicinal cookies arrayed below a sign saying, "Keep Out of Reach of Your Mother."
Several Bay Area doctors who recommend medical marijuana for their patients said in recent interviews that their client base had expanded to include teenagers with psychiatric conditions including attention deficit hyperactivity disorder.
"It's not everybody's medicine, but for some, it can make a profound difference," said Valerie Corral, a founder of the Wo/Men's Alliance for Medical Marijuana, a patients' collective in Santa Cruz that has two dozen minors as registered clients.
Because California does not require doctors to report cases involving medical marijuana, no reliable data exist for how many minors have been authorized to receive it. But Dr. Jean Talleyrand, who founded MediCann, a network in Oakland of 20 clinics who authorize patients to use the drug, said his staff members had treated as many as 50 patients ages 14 to 18 who had A.D.H.D. Bay Area doctors have been at the forefront of the fierce debate about medical marijuana, winning tolerance for people with grave illnesses like terminal cancer and AIDS. Yet as these doctors use their discretion more liberally, such support - even here - may be harder to muster, especially when it comes to using marijuana to treat adolescents with A.D.H.D.
"How many ways can one say 'one of the worst ideas of all time?' " asked Stephen Hinshaw, the chairman of the psychology department at the University of California, Berkeley. He cited studies showing that tetrahydrocannabinol, or THC, the active ingredient in cannabis, disrupts attention, memory and concentration - functions already compromised in people with the attention-deficit disorder.
Advocates are just as adamant, though they are in a distinct minority. "It's safer than aspirin," Dr. Talleyrand said. He and other marijuana advocates maintain that it is also safer than methylphenidate (Ritalin), the stimulant prescription drug most often used to treat A.D.H.D. That drug has documented potential side effects including insomnia, depression, facial tics and stunted growth.
In 1996, voters approved a ballot proposition making California the first state to legalize medical marijuana. Twelve other states have followed suit - allowing cannabis for several specified, serious conditions including cancer and AIDS - but only California adds the grab-bag phrase "for any other illness for which marijuana provides relief."
This has left those doctors willing to "recommend" cannabis - in the Alice-in-Wonderland world of medical marijuana, they cannot legally prescribe it - with leeway that some use to a daring degree. "You can get it for a backache," said Keith Stroup, the founder of the National Organization for the Reform of Marijuana Laws.
Nonetheless, expanding its use among young people is controversial even among doctors who authorize medical marijuana.
Gene Schoenfeld, a doctor in Sausalito, said, "I wouldn't do it for anyone under 21, unless they have a life-threatening problem such as cancer or AIDS."
Dr. Schoenfeld added, "It's detrimental to adolescents who chronically use it, and if it's being used medically, that implies chronic use."
Dr. Nora D. Volkow, director of the National Institute on Drug Abuse, said she was particularly worried about the risk of dependency - a risk she said was already high among adolescents and people with attention-deficit disorder.
Counterintuitive as it may seem, however, patients and doctors have been reporting that marijuana helps alleviate some of the symptoms, particularly the anxiety and anger that so often accompany A.D.H.D. The disorder has been diagnosed in more than 4.5 million children in the United States, according to the Centers for Disease Control and Prevention.
Researchers have linked the use of marijuana by adolescents to increased risk of psychosis and schizophrenia for people genetically predisposed to those illnesses. However, one 2008 report in the journal Schizophrenia Research suggested that the incidence of mental health problems among adolescents with the disorder who used marijuana was lower than that of nonusers.
Marijuana is "a godsend" for some people with A.D.H.D., said Dr. Edward M. Hallowell, a psychiatrist who has written several books on the disorder. However, Dr. Hallowell said he discourages his patients from using it, both because it is - mostly - illegal, and because his observations show that "it can lead to a syndrome in which all the person wants to do all day is get stoned, and they do nothing else."
Until the age of 18, patients requesting medical marijuana must be accompanied to the doctor's appointment and to the dispensaries by a parent or authorized caregiver. Some doctors interviewed said they suspected that in at least some cases, parents were accompanying their children primarily with the hope that medical authorization would allow the adolescents to avoid buying drugs on the street.
A recent University of Michigan study found that more than 40 percent of high school students had tried marijuana.
"I don't have a problem with that, as long as we can have our medical conversation," Dr. Talleyrand said, adding that patients must have medical records to be seen by his doctors.
The Medical Board of California began investigating Dr. Talleyrand in the spring, said a board spokeswoman, Candis Cohen, after a KGO-TV report detailed questionable practices at MediCann clinics, which, the report said, had grossed at least $10 million in five years.
Dr. Talleyrand and his staff members are not alone in being willing to recommend marijuana for minors. In Berkeley, Dr. Frank Lucido said he was questioned by the medical board but ultimately not disciplined after he authorized marijuana for a 16-year-old boy with A.D.H.D. who had tried Ritalin unsuccessfully and was racking up a record of minor arrests.
Within a year of the new treatment, he said, the boy was getting better grades and was even elected president of his special-education class. "He was telling his mother: 'My brain works. I can think,' " Dr. Lucido said.
"With any medication, you weigh the benefits against the risks," he added.
Even so, MediCann patients who receive the authorization must sign a form listing possible downsides of marijuana use, including "mental slowness," memory problems, nervousness, confusion, "increased talkativeness," rapid heartbeat, difficulty in completing complex tasks and hunger. "Some patients can become dependent on marijuana," the form also warns.
The White House's recent signals of more federal tolerance for state medical marijuana laws - which pointedly excluded sales to minors - reignited the debate over medical marijuana.
Some advocates, like Dr. Lester Grinspoon, an associate professor emeritus of psychiatry at Harvard University, suggest that medical marijuana's stigma has less to do with questions of clinical efficacy and more to do with its association, in popular culture, with illicit pleasure and addiction.
Others, like Alberto Torrico of Fremont, the majority leader of the California Assembly, argue for more oversight in general. "The marijuana is a lot more powerful these days than when we were growing up, and too much is being dispensed for nonmedical reasons," he said in an interview last week, bluntly adding, "Any children being given medical marijuana is unacceptable."
As advocates of increased acceptance try to win support, they may find their serious arguments compromised by the dispensaries' playful atmosphere.
OrganiCann, a dispensary in Santa Rosa, has a Web site advertisement listing the "medible of the week" - butterscotch rock candy - invitingly photographed in a gift box with a ribbon. OrganiCann also offers a 10 percent discount, every Friday, for customers with a valid student ID.