In the first placebo-controlled comparison, adolescents felt less stoned and had fewer memory impairments than adults from the same cannabis dose, but showed impaired impulse control and never felt satisfied, potentially driving escalated use.
Read this if you want to understand why teenagers might be especially prone to using more and more cannabis.
Teens felt less high but never felt satisfied, while adults felt high and satiated
What the researchers found
This groundbreaking study was the first to directly compare cannabis effects in adolescent (16-17) and adult (24-28) male users under controlled conditions.
The results defied simple assumptions about adolescent vulnerability. Compared to adults, adolescents reported feeling less stoned, had fewer psychotomimetic symptoms, less anxiety, and showed less memory impairment from cannabis. Their blood pressure and alertness were also less affected.
But alongside this apparent resilience, two concerning vulnerabilities emerged. First, cannabis impaired response inhibition (impulse control) in adolescents but not adults. Second, adolescents showed no satiety after cannabis: they wanted more regardless of whether they had received active or placebo cannabis, while adults felt satisfied after the active dose.
This combination of reduced subjective effects and lack of satiety could drive adolescents toward escalated use, as they may consume more to achieve the high adults get from less.
Why it matters
This is a landmark study. The contrasting profiles of adolescent resilience (blunted subjective and cognitive effects) and vulnerability (impaired inhibition and lack of satiety) provide a mechanistic explanation for why adolescent cannabis use tends to escalate: they feel the effects less, stop themselves less, and never feel they have had enough.
The numbers in context
20 adolescents (16-17) vs. 20 adults (24-28), all male cannabis users. Adolescents: less stoned, fewer psychotomimetic symptoms, less memory impairment, less anxiety. BUT: impaired response inhibition, no satiety (wanted more cannabis regardless of active/placebo). Adults: opposite pattern on all measures.
How the study worked
Placebo-controlled, double-blind, crossover design. 20 adolescent males (16-17 years) and 20 adult males (24-28 years), all current cannabis users. Vaporized active or placebo cannabis administered. Assessments: spatial working memory, episodic memory, response inhibition, blood pressure, heart rate, psychotomimetic symptoms, and subjective drug effects.
What this study cannot tell us
Only male participants. All were current cannabis users, so findings may not apply to naive users. Moderate sample size. Single-session design may not capture effects of regular use. Cannabis was standardized but may not represent typical potency.
How to read the evidence
Placebo-controlled crossover design with well-matched age groups. First study of its kind. Limited by male-only sample and moderate size.
When this study was published
Published in 2016. This landmark finding has influenced subsequent research on age-dependent cannabis effects.
The bigger picture
Animal research has long shown different adolescent and adult responses to cannabinoids. This study demonstrates these differences translate to humans and provides a neurobiological framework for understanding adolescent cannabis use patterns: the reduced sensitivity plus impaired inhibition plus absent satiety is a recipe for escalation.
Questions still open
- Would female adolescents show the same patterns? Does the lack of satiety persist with repeated use or develop tolerance? Could the impulse control deficit be targeted by interventions to reduce adolescent use escalation?
Common questions
Do teenagers react differently to cannabis than adults?
Why might this lead to escalated use in teens?
Read the original research
Are adolescents more vulnerable to the harmful effects of cannabis than adults? A placebo-controlled study in human males.
Translational psychiatry, 6(11), e961
Citation
Mokrysz, C; Freeman, T P; Korkki, S; Griffiths, K; Curran, H V. (2016). Are adolescents more vulnerable to the harmful effects of cannabis than adults? A placebo-controlled study in human males.. Translational psychiatry, 6(11), e961. https://doi.org/10.1038/tp.2016.225
Explore the wider topic
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- My Kid's Friends Smoke Weed: A Parent's Guide
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- Quitting Weed as a Parent: Why It Is the Hardest and Most Important Quit
- Quitting Weed as a Teen or Young Adult
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