Study: cannabis use among teenagers does not increase the risk of depression or suicide

According to a study published in the Journal of Affective Disorders, cannabis use among adolescents does not increase the risk of depression or suicidal thoughts.

Several recent research studies revealed the existence of a link between cannabis use among minors, depression and suicidal thoughts, without determining whether depressive states preceded or were the consequence of cannabis use.

A team of researchers from McGill University in Canada has designed a new study to examine this chicken-and-egg problem. The researchers recruited 1606 teenagers born in Quebec between 1997 and 1998 and followed them for 5 years. At ages 15, 17 and 20, subjects were asked to indicate the frequency of their depression or suicidal thoughts, and to track their weekly consumption of cannabis, alcohol and other drugs.

«This population-based study is the first, to our knowledge, to examine the temporal relationship between cannabis use, depression and suicidal ideation simultaneously over five years during adolescence.», have written the authors of the study.

At age 15, only 7 % of subjects were using cannabis, but by age 20, this rate had more than doubled to 15.6 %. Using statistical analysis, the researchers found that adolescents who suffered from depression were actually more likely to start using cannabis later in life. The study also indicates that cannabis itself does not increase the risk of suicidal thoughts, but that smoking weed while consuming other drugs and alcohol does increase this risk.

«Our study did not find that cannabis use alone was a risk factor for suicidal thoughts,» said lead author Despina Bolanis in a statement.

«On the contrary, the combination of other drug use, including cannabis, was a risk factor for suicidal thoughts.» The researchers also «found that depression was a risk factor for weekly cannabis use, supporting the 'self-medication» hypothesis. We demonstrated that cannabis has the ability to temporarily alleviate negative mood states that exist prior to its use.»

Although cannabis can provide some temporary relief from depression, Bolanis points out that weed use in adolescents can still be «problematic, as the underlying mood disturbance is still present and requires the attention of a mental health practitioner.»

A 2019 study published in Addiction also revealed that people suffering from depression are more likely to use cannabis, supporting the hypothesis that depression can lead to increased cannabis use.