A comprehensive analysis of more than 400 men over a 20-year period casts new doubt on the idea of marijuana use, even when long-term, being associated with physical and mental health problems later on in life. 
 
 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). 
 
 Half of the original group was selected because they represented the top 30 percent of those with reported conduct issues, while the other half was randomly picked from the class roster. Slightly more than half of the group was identified as black and the other half as white. 
 
 For 10 years, PYS researchers conducted regular follow-up interviews with these boys, first semiannually in their teens, and then annually until they turned 25. When they became 35 in 2010, the researchers subjected them to one last interview, with about 82 percent of those still living showing up for the occasion. 
 
 Because of the meticulous record-keeping by the PYS, the current authors were able to reliably track not only how healthy these boys were as they matured, but also their frequency of marijuana use over time. 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). They then compared the health status of these groups to one another, controlling for factors like tobacco use and socioeconomic status. 
 
 “[F]indings from this sample indicated 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,” they wrote. “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.” 
 
 As the researchers note, their results are somewhat surprising, flying in the face of previous studies that have found a small but real link between chronic marijuana use to the development of psychological issues like depression or schizophrenia, while reaffirming several other studies that found the opposite. In many ways, though, this study stands unique by being able to measure the health of its subjects as they grew up, rather than by looking back and asking people to remember when they first became sick or how much marijuana they once used when they were younger. 
 
 Research attempting to study the links between long-term marijuana use and actual health problems have largely been inconsistent, even if the reasoning behind a connection makes sense, such as with marijuana smoke being carcinogenic. 
 
 And even this latest study doesn’t come without its flaws. For one, only men were studied; only for 20 years, before the onset of conditions like cardiovascular disease; and only for certain diagnosable and self-reported health conditions. Maybe there isn’t a real association between depression and long-term marijuana use, but there could be one for less rigid symptoms like an increased sense of paranoia. 
 
 And the researchers theorize that maybe it’s a subset of people who are susceptible to the negative effects of long-term pot. “[I]t is increasingly being recognized that individual differences likely moderate the association between marijuana use and psychotic disorders,” they wrote. “For example, some studies have found that genetic liability affects whether, for whom, and the extent to which, marijuana has a negative influence on mental health.” 
 
 Similarly, other research suggests that marijuana doesn’t actually cause but rather accelerates the development of disorders like schizophrenia. 
 
 All of which is to say that this study, as the researchers themselves admit, isn’t the definitive answer to whether marijuana should become fully legalized, though it certainly is important. 
 
 “Indeed, marijuana policymakers and stakeholders need to consider the results of any single study in the context of the larger body of work on the potential adverse consequences of early onset chronic marijuana use,” they concluded. 
 
 Source: Bechtold J, Simpson T, White H, et al. Chronic Adolescent Marijuana Use as a Risk Factor for Physical and Mental Health Problems in Young Adult Men. Psychology of Addictive Behaviors. 2015. ||||| WASHINGTON -- Chronic marijuana use by teenage boys does not appear to be linked to later physical or mental health issues such as depression, psychotic symptoms or asthma, according to a study published by the American Psychological Association. 
 
 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. 
 
 "What we found was a little surprising," said lead researcher Jordan Bechtold, PhD, 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 use has undergone intense scrutiny as several states and the District of Columbia have legalized the drug, prompting the researchers to examine whether teen marijuana use has long-term health consequences. Based on some prior studies, they expected to find a link between teen marijuana use and the later development of psychotic symptoms (delusions, hallucinations, etc.), cancer, asthma or respiratory problems, but they found none. The study also found no link between teen marijuana use and lifetime depression, anxiety, allergies, headaches or high blood pressure. This study is one of just a few studies on the long-term health effects of teen marijuana use that have tracked hundreds of participants for more than two decades of their lives, Bechtold said. 
 
 The research was an offshoot of the Pittsburgh Youth Study, which began tracking 14-year-old male Pittsburgh public school students in the late 1980s to analyze various health and social issues. 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. The study sample was 54 percent black, 42 percent white and 4 percent other races or ethnicities. There were no differences in the findings based on race or ethnicity. 
 
 Participants were divided into four groups based on their reported marijuana use: low or non-users (46 percent); early chronic users (22 percent); participants who only smoked marijuana during adolescence (11 percent); and those who began using marijuana later in their teen years and continued using the drug (21 percent). Early chronic users reported much higher marijuana use, which rapidly increased during their teens to a peak of more than 200 days per year on average when they were 22 years old. Their marijuana use then declined somewhat as they got older. 
 
 The researchers controlled for other factors that could have influenced the findings, including cigarette smoking, other illicit drug use, and participants' access to health insurance. Since the study included only males, there were no findings or conclusions about women. Relatively few participants had psychotic symptoms, according to the study. 
 
 "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 said. 
 
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 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. 
 
 Full text of the article is available from the APA Public Affairs Office and at 
 
 http://www. apa. org/ pubs/ journals/ releases/ adb-adb0000103. pdf . 
 
 Contact: Jordan Bechtold at beardsleejb@upmc.edu or (949) 291-7520. 
 
 The American Psychological Association, in Washington, D.C., is the largest scientific and professional organization representing psychology in the United States. APA's membership includes more than 122,500 researchers, educators, clinicians, consultants and students. Through its divisions in 54 subfields of psychology and affiliations with 60 state, territorial and Canadian provincial associations, APA works to advance the creation, communication and application of psychological knowledge to benefit society and improve people's lives. 
 
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– 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.)