"'World of Warcraft,' and similarly intense video games, may cause socially withdrawn children to connect only with people in the game and to withdraw even further from social opportunities," said Richard Graham, a child psychiatrist at Tavistock.

More than 11 million people worldwide reportedly have registered as World of Warcraft players since the game was released this month, The Daily Telegraph reported Saturday.

"Some of my clients will discuss playing games for 14 to 16 hours a day at times without breaks and for those the consequences are potentially very severe," Graham said.

An example is 13-year-old Lorenzo Amato of Leece, Italy, who was hospitalized when he exhibited symptoms of a stroke, couldn't speak and failed to respond to his surroundings, the British newspaper reported.

Doctors determined Amato had been sickened by spending hours on his new PlayStation, the Telegraph reported, noting the teenager told his family to get rid of the computer game system. "If I even think about it I want to throw up," Amato was quoted as saying.