A new study found that even chronic marijuana use among teenage boys is not linked to physical or mental health issues later in life.

University of Pittsburgh Medical Center and Rutgers University researchers looked at 408 males and tracked them from their teenage years until their 30s. They did not observe a link between marijuana use and adverse health effects such as depression, psychotic symptoms and asthma. The study is one of the few on the subject that have tracked hundreds of participants for a period of more than two decades.

"What we found was a little surprising," said lead researcher Jordan Bechtold, a psychology research fellow at the University of Pittsburgh Medical Center. "There were no differences in any of the mental or physical health outcomes that we measured regardless of the amount or frequency of marijuana used during adolescence."

Marijuana legalization has been heavily debated, and several states and the District of Columbia have already legalized it. These recent developments have prompted researchers to take a closer look at the potential medical consequences associated with marijuana. Some past studies have suggested links between teen marijuana use and issues such as psychotic symptoms, asthma, and cancer, but this new study may refute some of these findings. The researchers also failed to find a link between teen marijuana use and "depression, anxiety, allergies, headaches or high blood pressure."

The study started looking at 14-year-old male Pittsburgh public school students in the late 1980s and surveyed them annually or semi-annually for a period of 12 years. a follow-up survey was conducted with 408 participants between 2009 and 2010 when they were 36 years old. The researchers split the participants into groups based on their level of marijuana use, and controlled for other health factors such as illicit drug and tobacco use as well as access to healthcare.

"We wanted to help inform the debate about legalization of marijuana, but it's a very complicated issue and one study should not be taken in isolation," Bechtold concluded.

The findings were published in a recent edition journal Psychology of Addictive Behaviors.