By Guy Bentley

Chronic marijuana use as an adolescent has no link to mental or physical health problems later in life, according to a new study conducted over the past 20 years.

Published by the American Physiological Association, researchers from the University of Pittsburgh Medical Center and Rutgers University divided participants into four groups from their teenage years onward.

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One group almost never smoked marijuana, one used it mostly in their teenage years, another started using in adulthood and the final group of subjects started using marijuana early and continued into their adult years.

There had been some evidence to suggest that regular marijuana use among teenagers was linked to mental problems such as depression and schizophrenia. Indeed, lead researcher Jordan Bechtold was expecting to find similar results and said what they discovered was “a little surprising.”

The study found that “chronic marijuana users were not more likely than late increasing users, adolescence-limited users, or low/nonusers to experience several physical or mental health problems in their mid-30s.”

In fact, there were no significant differences between marijuana trajectory groups in terms of adult health outcomes, even when models were run without controlling for potential confounds. The researchers found no link between teen marijuana use and lifetime depression, anxiety, allergies, headaches or high blood pressure.

The study also breaks new ground in that it was able to track 408 subjects as they grew up, rather than looking back on marijuana use retrospectively to find a link with current health problems. All the subjects were male and the study controlled for factors such as cigarette smoking and socioeconomic background.

Although the researchers caution that a single study shouldn’t be looked at in isolation, they argue it should contribute to debate surrounding marijuana legalization. Washington, Colorado, Alaska and Oregon have already legalized recreational marijuana use and campaigners are hoping to push the reforms nationwide.

“Everyone wants to prevent teen marijuana use, but we don’t need to exaggerate its harms and arrest responsible adults in order to do it,” Mason Tvert, communications director at the Marijuana Policy Project, told The Daily Caller News Foundation.

“Hopefully, this study will lead to a reevaluation of the tactics that are being used to discourage teens from trying marijuana,” he added.

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