Acute memory and psychotomimetic effects of cannabis and tobacco both ‘joint’ and individually: a placebo-controlled trial

Abstract

BackgroundCannabis and tobacco have contrasting cognitive effects. Smoking cannabis with tobacco is prevalent in many countries and although this may well influence cognitive and mental health outcomes, the possibility has rarely been investigated in human experimental psychopharmacological research.MethodThe individual and interactive effects of cannabis and tobacco were evaluated in 24 non-dependent cannabis and tobacco smokers in a randomized, placebo-controlled, double-blind, 2 (cannabis, placebo) × 2 (tobacco, placebo) crossover design. Verbal memory (prose recall), working memory (WM) performance including maintenance, manipulation and attention (N-back), psychotomimetic, subjective and cardiovascular measures were recorded on each of four sessions.ResultsCannabis alone impaired verbal memory. A priori contrasts indicated that tobacco offset the effects of cannabis on delayed recall. However, this was not supported by linear mixed model analysis. Cannabis load-dependently impaired WM. By contrast, tobacco improved WM across all load levels. The acute psychotomimetic effects and ratings of ‘stoned’ and ‘dizzy’ induced by cannabis were not altered by tobacco. Cannabis and tobacco had independent effects on increasing heart rate and interacting effects on increasing diastolic blood pressure.ConclusionsRelative to placebo, acute cannabis impaired verbal memory and WM. Tobacco enhanced performance on WM, independently of cannabis. Moreover, we found some preliminary evidence that tobacco may offset the effects of cannabis on delayed, but not immediate, verbal recall. In contrast, the psychotomimetic and subjective effects of cannabis were unaffected by tobacco co-administration. By reducing the cognitive impairment from cannabis, tobacco co-administration may perpetuate use despite adverse health consequences.

Cannabidiol reverses attentional bias to cigarette cues in a human experimental model of tobacco withdrawal

“…Anxiety was assessed with the State–Trait Anxiety Inventory (STAI) and depression with the Beck Depression Inventory (BDI) . A comprehensive drug history was taken . Pre‐morbid verbal intelligence was indexed by the Spot the Word task .…”

Experimental Effects of Exercise on Forgetting

“…Additionally, and similar to other studies [33][34][35][36], participants were excluded if they: Self-reported as a daily smoker [37,38] Self-reported being pregnant [39] Exercised within 5 hours of testing [40] Consumed caffeine within 3 hours of testing [41] Had a concussion or head trauma within the past 30 days [42] Took marijuana or other illegal drugs within the past 30 days [43] Were considered a daily alcohol user (>30 drinks/month for women; >60 drinks/month for men) [44]…”

Effect of Acute Moderate-Intensity Exercise on Autobiographical Episodic Memory and Semantic Memory

“…Similar to other studies [13], participants were excluded if they: Self-reported as a daily smoker [14,15] Self-reported being pregnant [16] Exercised within 5 hours of testing [17] Consumed caffeine within 3 hours of testing [18] Had a concussion or head trauma within the past 30 days [19] Took marijuana or other illegal drugs within the past 30 days [20] Were considered a daily alcohol user (>30 drinks/month for women; >60 drinks/month for men) [21]…”