A narrative review concluded that antidepressants are likely less effective for adolescents with depression or anxiety who frequently use cannabis, based on overlapping and potentially competing mechanisms of action.
Psychiatrists, pediatricians, parents of teens on antidepressants who also use cannabis, and clinical trial designers.
Nearly all antidepressant trials excluded cannabis users
What the researchers found
Almost all randomized clinical trials of antidepressants excluded participants using cannabis or other drugs, so the expected course of therapy in cannabis users is unknown. Based on shared neurochemical pathways (serotonin, endocannabinoid, and other systems), the authors concluded it is reasonable to assume antidepressants are less effective in adolescents who use cannabis frequently.
Why it matters
Depression and anxiety are rising in adolescents, antidepressant prescriptions are increasing, and cannabis is the most commonly used illicit substance in this age group. Yet virtually no clinical trial has studied what happens when these are combined.
The numbers in context
No specific numerical outcomes reported. The review identified overlapping neurochemical pathways between antidepressants (targeting serotonin, norepinephrine) and cannabinoids (THC and CBD effects on endocannabinoid system).
How the study worked
Narrative literature review examining the mechanisms of action of antidepressants and cannabis, focusing on neurochemical overlaps and potential interactions relevant to adolescent treatment outcomes.
What this study cannot tell us
Narrative review based on mechanistic reasoning rather than clinical outcome data. The conclusion that antidepressants are "less effective" is an inference, not an established finding from head-to-head studies.
How to read the evidence
Narrative review based on mechanistic reasoning from pharmacology, without direct clinical evidence of the proposed interaction.
When this study was published
Published in 2022.
The bigger picture
This represents a major blind spot in psychiatric treatment. Millions of adolescents take antidepressants, many also use cannabis, yet the interaction between these has essentially never been studied in a clinical trial.
Questions still open
- Should clinical trials of antidepressants in adolescents include cannabis users as a subgroup? Could CBD specifically interfere with or enhance antidepressant mechanisms?
Common questions
Does cannabis make antidepressants less effective?
Have antidepressants been tested in teens who use cannabis?
Read the original research
Examining the Use of Antidepressants for Adolescents with Depression/Anxiety Who Regularly Use Cannabis: A Narrative Review.
International journal of environmental research and public health, 19(1)
Citation
Hen-Shoval, Danielle; Weller, Aron; Weizman, Abraham; Shoval, Gal. (2022). Examining the Use of Antidepressants for Adolescents with Depression/Anxiety Who Regularly Use Cannabis: A Narrative Review.. International journal of environmental research and public health, 19(1). https://doi.org/10.3390/ijerph19010523
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