New study looks at the potential dangers of marijuana use

NEW YORK (WABC) -- While marijuana is becoming legal in some parts of the country, new research points out dangers, including just how addictive it can be for teens, and why it's more potent than ever before.

This study will not end the debate about whether it's safe or not, but it's in a major medical journal and as the push to legalize marijuana continues, the study will come up again.

This time researchers analyzed the studies that are out there, looking at marijuana and whether it's harmful or not. Their findings were just published in the New England Journal of Medicine.

Despite the debate, they found that marijuana is addictive. Among those who use the drug daily, one out of every six is considered addicted.

The new research also concludes that marijuana harms brain development.

Adults who smoked marijuana regularly as teenagers now have fewer nerve connections in the brain, including the areas that impact learning and memory.

And the researchers say the evidence is clear that immediate and long-term exposure to marijuana impairs your ability to drive and raises your risk of a motor vehicle accident.

What's not clear is if marijuana causes anxiety, depression or lung cancer. Despite the possible links, the researchers say it's still hard to prove, since so many factors play a role.

They did find that marijuana is now stronger than it used to be. The amount of the active ingredient THC has quadrupled since the 1980s, raising more concern about the possible risks.