Is Marijuana Harmful? – U.S. News & World Report (blog)

As more states consider decriminalizing marijuana, the scientific and public health communities are beginning to catch up with answers to some of the tough research questions about broad usage of the drug in the general population.

Is marijuana use addictive or habit-forming? Does it impair your ability to drive a car? Is it a gateway to the use of other illegal drugs? Does regular use increase the risk of cognitive impairment in adolescents?

[READ: Colorado Governor Calls Pot Legalization ‘Reckless’]

A new paper in the scientific journal Addiction (published by the Society for the Study of Addiction) has some definitive answers to these questions, based on a review of peer-reviewed research in adolescent and adult populations since 1993. The results, however, are not necessarily welcome ones for advocates of broad decriminalization of marijuana.

The paper, by lead researcher Wayne Hall from the University of Queensland Centre for Youth Substance Abuse Research, examined changes in the evidence on the adverse health effects of cannabis from 1993 to 2013. In effect, it looked at health outcomes in 1993, and compared them to the same health outcomes 20 years later. It found that:

See Photos

Marijuana Through the Years

* Research in the past 20 years has shown that driving while cannabis-impaired approximately doubles car crash risk;

* Around one in 10 regular cannabis users develop dependence;

* Regular cannabis use in adolescence doubles the risks of leaving school early (prior to high school graduation) and of cognitive impairment in adulthood.

That second point -that regular marijuana use is addictive to about 10 percent of the adolescent population- has also been borne out in other recent studies as well. It’s a worrisome effect for health officials.

The paper also found that regular use of marijuana in adolescents – again, based on comparing outcomes in 1993 to the same set …read more