A third "control" group consisted of students legitimately diagnosed with ADHD who took the same test.
"Almost nobody [in the fakers' group] failed the test," said Berry.
"Drugs is the obvious [motivation], but there are others," he continued. "Most universities provide people who have a diagnosis of ADHD with a variety of things that vary from one institution to another -- extra time on tests, copies of teachers' notes that they're lecturing from. They may get special accommodations in terms of where they're staying at the university, a single room versus a double room."
They can also get prescriptions for stimulants that can help them focus, the researchers said.
It's unclear how widespread the practice is, although Campo said her review of the literature had turned up prevalence rates of 8 percent to 35 percent.
The problem, she said, "is that there's always the risk of side effects when taking these medications: increasing blood pressure, tachycardia [abnormal heartbeat], anxiety symptoms. If you use them illegally and are vulnerable, you could become dependent."
Berry advocates using additional anti-fraud screening -- also called "malingering" tests -- to sort out the ADHD frauds from the legitimate cases. (In medical terms, "malingering" means fabricating or exaggerating symptoms of physical or mental disorders for a variety of "secondary gains" motives, such as drugs, money, or even sympathy and attention.)
"These should accompany the standard ADHD test," he said. "I think you can't use one without the other. You can't diagnose ADHD with the malingering test but you can't diagnose malingering with the ADHD test."
The U.S. National Institute of Mental Health has more on ADHD.
SOURCES: David Berry, Ph.D., pr
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