title: Cannabinoid modulation of amygdala reactivity to social signals of threat in humans.
abstract: The cannabinoid (CB) system is a key neurochemical mediator of anxiety and fear learning in both animals and humans. The anxiolytic effects of delta(9)-tetrahydrocannabinol (THC), the primary psychoactive ingredient in cannabis, are believed to be mediated through direct and selective agonism of CB(1) receptors localized within the basolateral amygdala, a critical brain region for threat perception. However, little is known about the effects of THC on amygdala reactivity in humans. We used functional magnetic resonance imaging and a well validated task to probe amygdala responses to threat signals in 16 healthy, recreational cannabis users after a double-blind crossover administration of THC or placebo. We found that THC significantly reduced amygdala reactivity to social signals of threat but did not affect activity in primary visual and motor cortex. The current findings fit well with the notion that THC and other cannabinoids may have an anxiolytic role in central mechanisms of fear behaviors and provide a rationale for exploring novel therapeutic strategies that target the cannabinoid system for disorders of anxiety and social fear.
authors.affiliation: Department of Psychiatry, University of Michigan and Veterans Affairs Ann Arbor Healthcare System, Ann Arbor, Michigan 48109, USA. luan@umich.edu
authors.forename: K Luan
authors.initials: KL
authors.lastname: Phan
authors.forename: Mike
authors.initials: M
authors.lastname: Angstadt
authors.forename: Jamie
authors.initials: J
authors.lastname: Golden
authors.forename: Ikechukwu
authors.initials: I
authors.lastname: Onyewuenyi
authors.forename: Ana
authors.initials: A
authors.lastname: Popovska
authors.forename: Harriet
authors.initials: H
authors.lastname: de Wit
mesh_terms: D000293:Adolescent; D000328:Adult; D000679:Amygdala / Q000187:drug effects* / Q000502:physiology; D002186:Cannabinoids / Q000494:pharmacology*; D004311:Double-Blind Method; D013759:Dronabinol / Q000494:pharmacology; D005239:Fear / Q000187:drug effects* / Q000502:physiology / Q000523:psychology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology; D012919:Social Behavior
chemical_list: D002186:Cannabinoids; D013759:Dronabinol