title: Are adolescents more vulnerable to the harmful effects of cannabis than adults? A placebo-controlled study in human males.
abstract: Preclinical research demonstrates that cannabinoids have differing effects in adolescent and adult animals. Whether these findings translate to humans has not yet been investigated. Here we believe we conducted the first study to compare the acute effects of cannabis in human adolescent (n=20; 16-17 years old) and adult (n=20; 24-28 years old) male cannabis users, in a placebo-controlled, double-blind cross-over design. After inhaling vaporized active or placebo cannabis, participants completed tasks assessing spatial working memory, episodic memory and response inhibition, alongside measures of blood pressure and heart rate, psychotomimetic symptoms and subjective drug effects (for example, 'stoned', 'want to have cannabis'). Results showed that on active cannabis, adolescents felt less stoned and reported fewer psychotomimetic symptoms than adults. Further, adults but not adolescents were more anxious and less alert during the active cannabis session (both pre- and post-drug administration). Following cannabis, cognitive impairment (reaction time on spatial working memory and prose recall following a delay) was greater in adults than adolescents. By contrast, cannabis impaired response inhibition accuracy in adolescents but not in adults. Moreover, following drug administration, the adolescents did not show satiety; instead they wanted more cannabis regardless of whether they had taken active or placebo cannabis, while the opposite was seen for adults. These contrasting profiles of adolescent resilience (blunted subjective, memory, physiological and psychotomimetic effects) and vulnerability (lack of satiety, impaired inhibitory processes) show some degree of translation from preclinical findings, and may contribute to escalated cannabis use by human adolescents.
authors.affiliation: Clinical Psychopharmacology Unit, Clinical Educational and Health Psychology, University College London, London, UK.
authors.forename: C
authors.identifier: 0000-0002-1970-8530
authors.initials: C
authors.lastname: Mokrysz
authors.affiliation: Clinical Psychopharmacology Unit, Clinical Educational and Health Psychology, University College London, London, UK.
authors.forename: T P
authors.initials: TP
authors.lastname: Freeman
authors.affiliation: Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK.
authors.forename: S
authors.initials: S
authors.lastname: Korkki
authors.affiliation: MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, UK.
authors.forename: K
authors.initials: K
authors.lastname: Griffiths
authors.affiliation: Clinical Psychopharmacology Unit, Clinical Educational and Health Psychology, University College London, London, UK.
authors.forename: H V
authors.initials: HV
authors.lastname: Curran
mesh_terms: D000280:Administration, Inhalation; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001143:Arousal / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002188:Cannabis / Q000009:adverse effects*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D061212:Memory, Episodic; D008570:Memory, Short-Term / Q000187:drug effects; D012528:Satiety Response / Q000187:drug effects; D065853:Spatial Learning / Q000187:drug effects