Does Cannabis Use Cause Behavior Problems in Teens?

As more and more countries move towards the decriminalization and legalization of cannabis, the number of underage cannabis users increases.

In fact, cannabis use now exceeds tobacco use among adolescents in the US. Similar trends are also emerging internationally.

Initial studies did not find an increase in teen cannabis use after cannabis legalization in the U.S. However, there is still some disagreement about whether cannabis legalization effects cannabis use in teens.

As a result, some are justifiably worried about the effect that a potential increase in cannabis use could have on adolescents.

That leads to the big question. Does cannabis use in teens lead to substance abuse or other psychological and behavioral problems?

A new study published in the journal Addiction answers gives us the answer and it might surprise you.

The Chicken or the Egg Conundrum

Previous research in the field of clinical psychology seemed to confirm parents’ worst fears. Increased substance use and/or dependence in teens is linked to the diagnosis of a psychiatric disorder including conduct disorder and oppositional-defiant disorder (ODD).

Research also shows that there’s a strong link between teen cannabis use and general conduct problems such as theft and truancy.

While these correlations are not controversial, there’s still debate about the cause and effect of the relationship.

Are teens that use cannabis more likely to develop behavior problems? Or are teens who already have behavior problems more likely to use cannabis?

The new study published in the journal Addiction successfully disentangles the complicated relationship between cannabis use in young people, conduct problems, as well as peer influences and cannabis substance abuse.

Let’s take a closer look.

Teen Survey and Unique Data Analysis

The new study used survey data from a previous survey study. The survey is called the Philadelphia Trajectory Study (PTS) and it contains survey responses from 364 adolescent participants.

The participants were between the ages of 12 and 14 at the beginning of the study. They were surveyed once a year for four years.

The survey involved computerized tasks and questionnaires designed to assess memory, self-control, impulsivity, and risk-taking behaviors. Participants also completed a final follow up two years after the fourth survey when they were between 19 and 21 years old.

Among the participants, there was a near even split between males and females. The participants were also racially and ethnically diverse and primarily from lower and middle-class families.

To analyze the PTS data, the researchers used one of the most sensitive methods for predicting cause and effect relationships.

The Results

The researchers found that while conduct problems predicted cannabis use, the reverse was not true.

This main finding on its own is hugely significant. It’s the first time that researchers have shown an increase in conduct problems comes before an increase in cannabis use in teens and not vice versa.

This effect was independent of peer cannabis use, gender, race-ethnicity, and socio-economic status.

Researchers also identified more complex “cascading links.” For example, early adolescent conduct problems predicted increased levels of peer cannabis use. Increased peer cannabis use also predicted later increase in individual cannabis use and ultimately cannabis abuse in late adolescence/early adulthood.

Having cannabis-using peers early in adolescence also predicted increased cannabis use and cannabis abuse.

However, the researchers found no evidence that cannabis use by itself led to conduct problems or peer cannabis use. They also found no evidence that peer cannabis use predicted conduct problems.

Unlike many of the previous studies, the current study controlled for previous levels of conduct problems, cannabis use and cannabis using peers.  Many other publications report consistent findings — teens with conduct problems are more likely to use cannabis, but the use of cannabis does not predict the appearance of conduct problems.


Self-reported studies have a few clear limitations that should always be kept in mind when considering research results.

For example, mood and memory can affect survey responses. Participants are also known to fall prey to the social desirability bias, the tendency to over-report “good” behavior and under-report “bad” behavior.

An Eye Towards Prevention

Other research suggests that teens with conduct problems use cannabis as a coping mechanism or as a way to self-medication. This could explain why cannabis use tends to follow the appearance of conduct problems in young people.

Conduct problems can also be an early manifestation of a young person’s lack of self-control. Poor self-control is another strong predictor of substance use and abuse.

The study’s findings could help experts identify children and teens who are more at risk for developing substance abuse disorders.

Young people who exhibit early signs of conduct problems could be identified as at risk in the hopes of preventing later substance abuse issues.

Counselors, mental health professionals, and family members should make healthier, alternative coping strategies and personal support available to children and teens with showing signs of conduct problems.

Lastly, future studies looking at the effects of parental influences might help to further determine the best strategy for preventing cannabis and other substance abuse issues in teens.

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