Principle investigator Kevin Clauson, an associate professor at Nova Southeastern University's College of Pharmacy, said the poker players used drugs such as marijuana, cocaine, amphetamines, Valium and other prescription medications, as well caffeine, energy drinks and guarana -- a plant containing more caffeine than coffee beans.
Clauson and colleagues interviewed poker players in Las Vegas during the World Series of Poker and then surveyed players online worldwide, although most were from the United States and Canada.
"The use of these substances could allow poker players to stay awake longer, as well as focus and concentrate better, which would be a competitive advantage," Clauson said in a statement. "Stamina is important for any poker player because tournament poker and cash games can go on for many hours."
The study found 73 percent of the respondents -- mostly male and in their 20s -- said they used drugs and other substances to focus and concentrate, while the rest said they used the drugs or substances to calm their nerves, stay awake and improve memory.
The study is at slideshare.net/kclauson/use-of-cognitive-and-performance-enhancing-medications-in-poker-players.