Previous cannabis exposure modulates the acute effects of delta-9-tetrahydrocannabinol on attentional salience and fear processing

Cannabis can induce transient psychotic and anxiety symptoms and long-lasting disorders. The acute psychoactive effects of its main active ingredient, (-)-trans-Δ9-tetrahydrocannabinol (Δ9-THC), may be modulated by previous cannabis exposure. Secondary data analyses tested whether modest previous cannabis exposure modulated the acute effects of Δ9-THC on attentional salience and emotional processing and their neurophysiological substrates. Twenty-four healthy men participated in a doubleblind, randomized, placebo-controlled, repeated-measures, within-subject, Δ9-THC challenge study using fMRI. Compared with nonusers (NUs; n = 12;