One in five scientists admits to use prescription drugs to improve their focus, concentration or memory, an online survey finds.

The overwhelming majority say they take the drugs to improve concentration, and about half say they do so daily or weekly.

The survey focused on three drugs available by prescription or via the internet.

Ritalin, a trade name for methylphenidate, is a stimulant normally used to treat attention-deficit hyperactivity disorder, especially in children; modafinil, marketed at Modavigil in Australia, is prescribed to treat sleep disorders, but is also used unofficially to counter general fatigue and jet lag; and beta-blockers, cardiovascular drugs prescribed for heart failure and high blood pressure that also have an anti-anxiety effect.

"It alerted us to the fact that scientists, like others, are looking for short cuts," says Dr Wilson Compton, director of epidemiology and prevention research at the US National Institute on Drug Abuse.