Of these , the metabolite produces the greatest psychoactive effects .
Cannabidiol ( CBD ) is not psychoactive but plays a modulating role on cannabis psychoactive effects .
The proportion of 9-THC in plant material is higher ( up to 40 % ) than in other cannabinoids ( up to 9 % ) .
Conclusions Findings reveal that 9-THC contributes the most to cannabis psychoactivity .
Due to lower psychoactive potency and smaller proportions in plant material , other psychoactive cannabinoids have a weak influence on cannabis final effects .
Objective This systematic review aims to summarize current evidence on which naturally present cannabinoids contribute to  cannabis psychoactivity  , considering their reported concentrations and pharmacodynamics in humans .
Cannabidiol in Humans—The Quest for Therapeutic Targets
Cannabidiol ( CBD ) , a major phytocannabinoid constituent of cannabis , is attracting growing attention in medicine for its anxiolytic , antipsychotic , antiemetic and anti-inflammatory properties . However , up to this point , a comprehensive literature review of the effects of CBD in humans is lacking . The aim of the present systematic review is to examine the r and omized and crossover studies that administered CBD  to healthy controls and to clinical patients . A systematic search was performed in the electronic data bases PubMed and EMBASE using the key word “ cannabidiol ” . Both monotherapy and combination studies ( e.g. , CBD + ∆9-THC ) were included . A total of 34 studies were identified : 16 of these were experimental studies , conducted in healthy subjects , and 18 were conducted in clinical population s , including multiple sclerosis ( six studies ) , schizophrenia and bipolar mania ( four studies ) , social anxiety disorder ( two studies ) , neuropathic and cancer pain ( two studies ) , cancer anorexia ( one study ) , Huntington ’s disease ( one study ) , insomnia ( one study ) , and epilepsy ( one study ) . Experimental studies indicate that a high-dose of inhaled/intravenous CBD is required to inhibit the effects of a lower dose of ∆9-THC . Moreover , some experimental and clinical studies suggest that oral/oromucosal CBD may prolong and /or intensify ∆9-THC-induced effects , whereas others suggest that it may inhibit ∆9-THC-induced effects . Finally , preliminary clinical trials suggest that high-dose oral CBD ( 150–600 mg/d ) may exert a therapeutic effect for social anxiety disorder , insomnia and epilepsy , but also that it may cause mental sedation . Potential pharmacokinetic and pharmacodynamic explanations for these results are discussed
Of these , the metabolite produces the greatest psychoactive effects .
Cannabidiol ( CBD ) is not psychoactive but plays a modulating role on cannabis psychoactive effects .
The proportion of 9-THC in plant material is higher ( up to 40 % ) than in other cannabinoids ( up to 9 % ) .
Conclusions Findings reveal that 9-THC contributes the most to cannabis psychoactivity .
Due to lower psychoactive potency and smaller proportions in plant material , other psychoactive cannabinoids have a weak influence on cannabis final effects .
Objective This systematic review aims to summarize current evidence on which naturally present cannabinoids contribute to  cannabis psychoactivity  , considering their reported concentrations and pharmacodynamics in humans .