The authors of the study, published in Psychology of Addictive Behaviors, looked at data taken from the Pittsburgh Youth Study (PYS), a longitudinal study that attempted to track the development of antisocial and delinquent behavior among a selected group of first, third, and seventh grade boys attending public school in Pittsburgh from 1987 to 1988 (For the purposes of this current study, only data on the seventh grade boys, totaling 506 kids, was used). For 12 years, participants were surveyed annually or semiannually, and a follow-up survey was conducted with 408 participants in 2009-10 when they were 36 years old. They ultimately divided the subjects into one of four groups: Those who rarely or never used marijuana (46 percent); those who mostly used it in their teens (11 percent); those who took up the habit in adulthood (21 percent); and those who started early and become chronic — pun intended — pot users as they grew up (22 percent). ### 
 
 Article: "Chronic Adolescent Marijuana Use as a Risk Factor for Physical and Mental Health Problems in Young Adult Men;" Jordan Bechtold, PhD, and Dustin Pardini, PhD University of Pittsburgh Medical Center; Theresa Simpson, MA, and Helene R. White, PhD; Rutgers University; Psychology of Addictive Behaviors; published online Aug. 3, 2015. Researchers from the University of Pittsburgh Medical Center and Rutgers University tracked 408 males from adolescence into their mid-30s for the study, which was published in Psychology of Addictive Behaviors.
– Previous studies have found teen marijuana use could result in cancer, asthma, respiratory problems, and psychotic symptoms like delusions and hallucinations over time. That's why researchers say the results of a new long-term study following teen pot smokers into their 30s are "a little surprising." Researchers who analyzed 408 males for health and social issues from age 14 to 26, then checked back in with the participants at age 36, found no connection between pot use and any of the aforementioned conditions. Not only that, the study in Psychology of Addictive Behaviors—an extension of the Pittsburgh Youth Study of the 1980s—also found no apparent link between smoking marijuana as a teen and later depression, anxiety, allergies, headaches, or high blood pressure, according to a press release. The participants—54% black, 42% white—were classed into four groups: those who rarely or never used marijuana (46%); chronic users who started using the drug early (22%); those who picked up the habit as an adult (21%); and those who smoked marijuana only in their youth (11%). "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," a researcher explains. That means chronic users who smoked the drug 200 days a year on average at age 22 were no more likely to have health problems than those who rarely or never picked up a joint. Researchers say the study should "help inform the debate about legalization of marijuana," but "should not be taken in isolation" as negative health effects may appear in those with a genetic liability, per Medical Daily. (Marijuana apparently heals broken bones.)