Teenagers who start using cannabis before age 15 are more likely to use the drug frequently later in life. They are also more likely to develop mental and physical health problems in early adulthood compared to their peers who did not use the drug during adolescence.
These are the findings of a new study published in the JAMA Network Open.
“This further reinforces the argument that cannabis use during adolescence negatively affects the health trajectories of those who use it,” says psychiatrist Dr. Ryan Sultan of Columbia University, who did not participate in the new research.
The new study used data from the Quebec Longitudinal Study of Child Development. Researchers in Montreal, Canada, have been tracking more than 1,500 children from birth into early adulthood to understand the factors that influence their development and health. Among the various aspects of the children’s lives and habits that the scientists recorded is cannabis use between ages 12 and 17.
The researchers found that the majority of teenagers—60%—did not use cannabis during adolescence. Among the remaining 40%, half started using cannabis in late adolescence and, by age 17, used the drug sporadically—less than once a month. The remaining 20% started using marijuana before age 15, and by age 17, were already using it at least once a month.
This last group was more likely to seek medical care in early adulthood for both mental and physical health conditions, compared to those who did not use the drug during adolescence.
“The risk is concentrated among those who start early and use frequently,” says psychologist and lead study author Massimiliano Orri of McGill University.
Early and frequent cannabis users had 51% higher odds of seeking care for mental health problems in early adulthood compared to those who did not use the drug. And this risk was calculated after controlling for a range of known confounding factors that influence health, such as bullying or lack of parental involvement.
Similarly, early and frequent cannabis users had 86% higher odds of needing care for physical health problems.
“We have some indication that respiratory problems were the most frequently reported, as well as accidents and unintentional injuries,” says Orri.
These physical health problems may be related to cannabis intoxication, but also to withdrawal symptoms, Orri and his colleagues write in the paper.
“This makes perfect sense,” says psychologist Krista Lisdahl of the University of Wisconsin in Milwaukee, who also studies adolescent brain development and health but did not participate in the new research. “It’s alarming and something we need to monitor more closely here in the United States as well.”
A major strength of the study is that Orri and his colleagues controlled for so many confounding factors, Lisdahl adds.
“There are many factors that are intertwined with physical health, just as with mental health,” says Lisdahl. And the new study controlled for many of them, including “family conflict, parenting style, and parental monitoring of teenagers.” They also analyzed individual-level factors, such as social skills, peer relationships, and whether the child was victimized by peers.
Previous studies have also found a link between adolescent cannabis use and higher risk of developing mental health symptoms.
Sultan’s recent research found two to four times higher odds of developing psychiatric disorders for teenagers who used cannabis recreationally compared to teenagers who do not use the drug. Other studies have suggested a link between early cannabis use and psychosis in young people. He and his colleagues have also found higher risk of other impacts, such as worse grades and school dropout.
“The adolescent brain continues to develop very dynamically during adolescence and into early adulthood,” says Lisdahl. “Using something like cannabis regularly during that period can disrupt that healthy neural development, especially in brain areas related to executive function, which is things like problem-solving, planning, perhaps control of other types of behaviors and impulses, but also emotional regulation,” she says.
Take, for example, a teenager prone to anxiety who turns to cannabis to feel less anxious, says Sultan. “If you start doing that regularly, that now becomes your method for managing anxiety,” he says. “It becomes your coping skill and you become atrophied in any ability to manage it in other ways.”
The same thing can happen with someone who uses cannabis to manage mood, he adds.
So, for someone who already has a predisposition to some mental health symptoms, starting cannabis use in adolescence can make it more likely that those symptoms worsen over time, evolving into mental health disorders.
For all these reasons, Sultan—a child and adolescent psychiatrist—says he often talks with teenagers and parents about delaying cannabis use until age 25, to minimize the risks of health and behavioral problems later in life.
Source: npr.org by Rhitu Chatterjee