Marijuana use among U.S. teens rises

More U.S. teens appear to be smoking marijuana compared to last year, suggests a survey of students released Monday.

The annual survey on drug use by students in grades 8, 10 and12 was conducted by researchers at the University of Michigan'sNational Institute on Drug Abuse for the U.S. government.

Marijuana was the most commonly used illicit drug. Its use had been decreasing, but that decade-long trend seemed to end this year, the researchers said in the report, titled "Monitoring the Future."

According to the study of 47,097 students, in2009, marijuana use in the prior 12 months was reported by about 12 per cent of Grade 8 students, 27 per cent of Grade 10 students and a third of Grade 12 students.

Marijuana use peaked in the late 1990s.

'Upwarding trend'

Among students in Grade 12 this year, 20.6 per cent said they used it within the past month, comparedto 19.4 per cent in 2008 and 18.3 per cent in 2006.

Among Grade 10 students, marijuanause in the past month rose to 15.9 per cent this year from 13.8 per cent in 2008.

"The upward trending of the past two or three years standsin stark contrast to the steady decline that preceded it for nearly a decade," said Lloyd Johnston, who has directed the annual survey since it started in 1975.

Fewer Grade 8 students said they saw a "great risk" from occasionally smoking, 44.8 per cent this year, down from 50.5 per cent in 2004.

"When the perception of the danger goes down, in the following years you see an increase in use," said Nora Volkow, director of the National Institute on Drug Abuse.

The proportions saying they used any illicit drug in the past year were 15 per cent, 29 per cent and 37 per cent, in grades 8, 10 and 12, respectively.

Teens may mistakenly believe prescription drugs are less dangerous "because they're endorsed by the medical community," without realizing prescription narcotics such as OxyContin and Vicodin are highly addictive and can act as gateways to heroin, which is cheaper, Volkow said.

Alcohol continue to be the most widely used substance among U.S. teens, with 43.5 per cent ofGrade 12 studentsreporting taking a drink in the past month, although use appears to be down substantially. In 1997, 52.7 per cent said they had consumed alcohol in the past month.

There were also declines this year in the use of LSD and other hallucinogens, cigarettes, and methamphetamine.