Poll findings suggest that up to one-fifth of adults may be using prescription drugs like Ritalin "off-label" to increase alertness and mental awareness, the Telegraph reported Oct. 14.

One in five of the 1,400 adults who responded to the survey conducted by the journal Nature -- including college students and shift workers -- admitted taking Ritalin, Provigil (modafinil) or beta-blockers to stimulate focus, concentration or memory. Most users obtained the drugs by prescription or bought them on the Internet. The drugs are intended to treat mental-health problems like attention-deficit disorder, but also can act as stimulants.

The popularity of these drugs suggests that need for more information about their safety, said Barbara Sahakian, a neuropsychologist at Addenbrooke's Hospital. "The use of these cognitive enhancing drugs is spreading to younger and younger people," she said.

Sahakian, whose own research found that 17 percent of students in some U.S. universities admit to using Ritalin, said that more research on the effects of cognitive enhancing drugs is needed. "We do not really have long-term efficacy and safety data in healthy people," she said.

Survey results are available at the Nature website.