New college policies about A.D.H.D. tend not to apply to other medical or psychiatric conditions — suggesting discrimination, said Ruth Hughes, the chief executive of the advocacy group Children and Adults With Attention-Deficit/Hyperactivity Disorder. Such rules create “a culture of fear and stigma,” she said, adding that if students must sign a contract to obtain stimulants, they should have to do so for the painkillers that are also controlled substances and are known to be abused.

“If a university is very concerned about stimulant abuse, I would think the worst thing they could do is to relinquish this responsibility to unknown community practitioners,” Ms. Hughes said. “Nonprescribed use of stimulant medications on campus is a serious problem that can’t just be punted to someone else outside the school grounds.”

Fresno State officials said a disquieting surge of students requesting A.D.H.D. diagnoses — along with news media reports of stimulant abuse and questionable diagnostic practices nationwide — led the university to change several policies last year. Now, students with an outside diagnosis of A.D.H.D. can fill their prescriptions at the Student Health Center only after providing documentation of a thorough evaluation by qualified mental health practitioners — which typically involves hours of neuropsychological testing and conversations with parents and teachers to assess impairment and other possible explanations.

Fresno State no longer makes diagnoses, largely because of the substantial time required “to do it right,” said Catherine Felix, its director of health and psychological services. Many universities, including North Carolina State, Georgia Tech and Penn State, also said they could no longer handle the volume of requests.

In addition to requiring students to sign the contract, Fresno State does not allow early refills to replace lost or stolen medication. Urine tests can be required should a university clinician suspect that a student is not taking the pills as prescribed.

And in a rare policy among colleges, students receiving prescriptions to treat A.D.H.D. must see a Fresno State therapist regularly — not for a cursory five-minute “med check” but for at least one 50-minute session a month.

“It’s not just taking a pill every day,” said Dr. Daniel Little, who counsels several students with A.D.H.D. under this arrangement. “It’s about learning coping skills.”