The seed and the soil: effect of dosage, personality and starting state on the response to delta 9 tetrahydrocannabinol in man

Biphasic effects of cannabis and cannabinoid therapy on pain severity, anxiety, and sleep disturbance: a scoping review

INTRODUCTION

Cannabinoids are being used by patients to help with chronic pain management and to address the 2 primary chronic pain comorbidities of anxiety and sleep disturbance. It is necessary to understand the biphasic effects of cannabinoids to improve treatment of this symptom triad.

METHODS

A scoping review was conducted to identify whether biphasic effects of cannabinoids on pain severity, anxiolysis, and sleep disturbance have been reported. The search included the Embase, Biosis, and Medline databases of clinical literature published between 1970 and 2021. The inclusion criteria were (1) adults more than 18 years of age, (2) data or discussion of dose effects associated with U-shaped or linear dose responses, and (3) measurements of pain and/or anxiety and/or sleep disturbance. Data were extracted by 2 independent reviewers (with a third reviewer used as a tiebreaker) and subjected to a thematic analysis.

RESULTS

After the database search and study eligibility assessment, 44 publications met the final criteria for review. Eighteen publications that specifically provided information on dose response were included in the final synthesis: 9 related to pain outcomes, 7 measuring anxiety, and 2 reporting sleep effects.

CONCLUSIONS

This scoping review reports on biphasic effects of cannabinoids related to pain, sleep, and anxiety. Dose-response relationships are present, but we found gaps in the current literature with regard to biphasic effects of cannabinoids in humans. There is a lack of prospective research in humans exploring this specific relationship.

Is cannabis treatment for anxiety, mood, and related disorders ready for prime time?

Anxiety and related disorders are the most common mental conditions affecting the North American population. Despite their established efficacy, first-line antidepressant treatments are associated with significant side effects, leading many afflicted individuals to seek alternative treatments. Cannabis is commonly viewed as a natural alternative for a variety of medical and mental health conditions. Currently, anxiety ranks among the top five medical symptoms for which North Americans report using medical marijuana. However, upon careful review of the extant treatment literature, the anxiolytic effects of cannabis in clinical populations are surprisingly not well-documented. The effects of cannabis on anxiety and mood symptoms have been examined in healthy populations and in several small studies of synthetic cannabinoid agents but there are currently no studies which have examined the effects of the cannabis plant on anxiety and related disorders. In light of the rapidly shifting landscape regarding the legalization of cannabis for medical and recreational purposes, it is important to highlight the significant disconnect between the scientific literature, public opinion, and related policies. The aim of this article is to provide a comprehensive review of the current cannabis treatment literature, and to identify the potential for cannabis to be used as a therapeutic intervention for anxiety, mood, and related disorders. Searches of five electronic databases were conducted (PubMed, MEDLINE, Web of Science, PsychINFO, and Google Scholar), with the most recent in February 2017. The effects of cannabis on healthy populations and clinical psychiatric samples will be discussed, focusing primarily on anxiety and mood disorders.

The fatty acid amide hydrolase inhibitor URB597 modulates serotonin-dependent emotional behaviour, and serotonin1A and serotonin2A/C activity in the hippocampus

The fatty acid amide hydrolase (FAAH) inhibitor URB597 increases anandamide, resulting in antidepressant/anxiolytic-like activity, likely via CB1 receptor-mediated modulation of serotonin (5-HT) and norepinephrine (NE) neurotransmission. However, the relative importance of the 5-HT and NE systems in these effects and on effects of URB597 on postsynaptic 5-HT receptors remain to be determined. Using behavioural and electrophysiological approaches, we assessed the effects of acute-single and repeated URB597 treatment on responses predicting antidepressant/anxiolytic activity, and on hippocampal 5-HT1A and 5-HT2A/C receptor sensitivity. Acute-single or serial URB597 treatment, compared to vehicle, reduced immobility in the forced swim test (FST), increased open arm visits in the elevated plus maze and shortened feeding latency in the novelty-suppressed feeding test (NSFT). Repeated URB597 treatment yielded more profound behavioural effects, which were associated with an increase in hippocampal brain-derived neurotrophic factor (BDNF). The 5-HT synthesis inhibitor para-chlorophenylalanine (pCPA), but not the NE neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4) prevented URB597-mediated antidepressant/anxiolytic-like response in the FST and NSFT, while DSP4 did not further affect URB597-mediated increase in raphe 5-HT neuron firing. Repeated URB597 administration decreased hippocampal pyramidal firing in response to 5-HT2A/C and 5-HT1A stimulation with 1-[2,5-dimethoxy-4-iodophenyl]-2-aminopropane (DOI) and 8-hydroxy-2-dipropylaminotetralin (8-OH-DPAT), respectively, suggesting plastic adaptation of these receptors. The effects of acute-single and repeated URB597 administration on hippocampal cell firing in response to DOI or 8-OH-DPAT were similar in magnitude and intensity to the positive control citalopram. These data indicate that URB597 acts, either directly or indirectly, on the 5-HT system, increases hippocampal BDNF expression, and modifies 5-HT1A and 5-HT2A/C function.

The relationship between bipolar disorder and cannabis use in daily life: an experience sampling study

Objectives

Although cannabis use is common in bipolar disorder and may contribute to worse clinical outcomes, little is understood about the relationship between this drug and bipolar disorder over the course of daily life. The aim of study was to examine the effect of cannabis on affect and bipolar symptoms in a group of individuals with bipolar disorder.

Methods

Twenty-four participants with bipolar disorder type I or type II completed diaries for 6 days using Experience Sampling Methodology to investigate the temporal associations between cannabis, affect and bipolar disorder symptoms.

Results

The results indicated that higher levels of positive affect increase the odds of using cannabis (OR:1.25 ,CI:1.06–1.47, P=0.008). However, neither negative affect, manic nor depressive symptoms predicted the use of cannabis. Cannabis use was associated with subsequent increases in positive affect (β=0.35, CI:0.20-0.51, P=0.000), manic symptoms (β=0.20,CI:0.05-0.34, P=0.009) and depressive symptoms (β= 0.17,CI:0.04-0.29, P=0.008).

Conclusion

The findings indicate that cannabis use is associated with a number of subsequent psychological effects. However there was no evidence that individuals with BD were using cannabis to self-medicate minor fluctuations in negative affect or bipolar disorder symptoms over the course of daily life. The findings in relation to existing literature and clinical implications are discussed.

The influence of personality on the sensitivity to subjective effects of Δ9-tetrahydrocannabinol

The effects of drugs are not only determined by their pharmacological action, but also by user characteristics. This analysis explored the influence of personality on the differences in subjective effects in response to a standardized pharmacological challenge with the cannabinoid CB1/CB2 partial agonist Δ9-tetrahydrocannabinol (THC). To express the sensitivity to THC, pharmacokinetic–pharmacodynamic (PK–PD) non-linear mixed effects modelling was applied to the subjective response of 184 healthy subjects to a pharmacological challenge with inhalation of THC. The subjective effects were measured using visual analogue scales and described by three clusters: ‘perception’, ‘relaxation’ and ‘dysphoria’. The sensitivity for THC (described as EC50) was related to scores on Cloninger׳s temperament and character inventory (TCI) using multiple linear regression. Effect compartment models were used to describe the PK–PD relations of THC. Within the multivariate model, ‘harm avoidance’ was significantly correlated with changes in ‘perception’, and ‘self-transcendence’ with changes in ‘dysphoria’. Within the psychobiological model of personality, ‘harm avoidance’ is related to serotonergic systems. Subjects with either very low (easy-going) or very high (cautious) scores were less sensitive to THC-induced changes in ‘perception’. ‘Self-transcendence’ relates to schizotypy. Subjects with more schizotypy were more sensitive to the dysphoric subjective effects of THC.

Marijuana's dose-dependent effects in daily marijuana smokers

Active marijuana produces significant subjective, psychomotor, and physiological effects relative to inactive marijuana, yet demonstrating that these effects are dose-dependent has proven difficult. This within-subject, double-blind study was designed to develop a smoking procedure to obtain a marijuana dose-response function. In four outpatient laboratory sessions, daily marijuana smokers (N = 17 males, 1 female) smoked six 5-s puffs from 3 marijuana cigarettes (2 puffs/cigarette). The number of puffs from active (≥5.5% Δ⁹-tetrahydrocannabinol/THC) and inactive (0.0% THC) marijuana varied according to condition (0, 2, 4, or 6 active puffs); active puffs were always smoked before inactive puffs. Subjective, physiological, and performance effects were assessed prior to and at set time points after marijuana administration. Active marijuana dose-dependently increased heart rate and decreased marijuana craving, despite evidence (carbon monoxide expiration, weight of marijuana cigarettes post-smoking) that participants inhaled less of each active marijuana cigarette than inactive cigarettes. Subjective ratings of marijuana "strength," "high," "liking," "good effect," and "take again" were increased by active marijuana compared with inactive marijuana, but these effects were not dose-dependent. Active marijuana also produced modest, non-dose-dependent deficits in attention, psychomotor function, and recall relative to the inactive condition. In summary, although changes in inhalation patterns as a function of marijuana strength likely minimized the difference between dose conditions, dose-dependent differences in marijuana's cardiovascular effects and ratings of craving were observed, whereas subjective ratings of marijuana effects did not significantly vary as a function of dose.

Endocannabinoid system dysfunction in mood and related disorders

OBJECTIVE

The endocannabinoid (EC) system is widely distributed throughout the brain and modulates many functions. It is involved in mood and related disorders, and its activity may be modified by exogenous cannabinoids. This article examines the therapeutic potential of cannabinoids in psychiatric disorders.

METHOD

An overview is presented of the literature focussed on the functions of the EC system, its dysfunction in mood disorders and the therapeutic potential of exogenous cannabinoids.

RESULTS

We propose (hypothesize) that the EC system, which is homoeostatic in cortical excitation and inhibition, is dysfunctional in mood and related disorders. Anandamide, tetrahydrocannabinol (THC) and cannabidiol (CBD) variously combine antidepressant, antipsychotic, anxiolytic, analgesic, anticonvulsant actions, suggesting a therapeutic potential in mood and related disorders. Currently, cannabinoids find a role in pain control. Post mortem and other studies report EC system abnormalities in depression, schizophrenia and suicide. Abnormalities in the cannabinoid-1 receptor (CNR1) gene that codes for cannabinoid-1 (CB1) receptors are reported in psychiatric disorders. However, efficacy trials of cannabinoids in psychiatric disorders are limited but offer some encouragement.

CONCLUSION

Research is needed to elucidate the role of the EC system in psychiatric disorders and for clinical trials with THC, CBD and synthetic cannabinoids to assess their therapeutic potential.

Phytocannabinoids as novel therapeutic agents in CNS disorders

The Cannabis sativa herb contains over 100 phytocannabinoid (pCB) compounds and has been used for thousands of years for both recreational and medicinal purposes. In the past two decades, characterisation of the body's endogenous cannabinoid (CB) (endocannabinoid, eCB) system (ECS) has highlighted activation of central CB(1) receptors by the major pCB, Δ(9)-tetrahydrocannabinol (Δ(9)-THC) as the primary mediator of the psychoactive, hyperphagic and some of the potentially therapeutic properties of ingested cannabis. Whilst Δ(9)-THC is the most prevalent and widely studied pCB, it is also the predominant psychotropic component of cannabis, a property that likely limits its widespread therapeutic use as an isolated agent. In this regard, research focus has recently widened to include other pCBs including cannabidiol (CBD), cannabigerol (CBG), Δ(9)tetrahydrocannabivarin (Δ(9)-THCV) and cannabidivarin (CBDV), some of which show potential as therapeutic agents in preclinical models of CNS disease. Moreover, it is becoming evident that these non-Δ(9)-THC pCBs act at a wide range of pharmacological targets, not solely limited to CB receptors. Disorders that could be targeted include epilepsy, neurodegenerative diseases, affective disorders and the central modulation of feeding behaviour. Here, we review pCB effects in preclinical models of CNS disease and, where available, clinical trial data that support therapeutic effects. Such developments may soon yield the first non-Δ(9)-THC pCB-based medicines.

Acute Effects of Marijuana Smoking on Negative and Positive Affect

Human studies and animal experiments present a complex and often contradictory picture of the acute impact of marijuana on emotions. The few human studies specifically examining changes in negative affect find either increases or reductions following delta-9-tetrahydrocannabinol (THC) administration. In a 2 × 2, instructional set (told THC vs. told no THC) by drug administration (smoked marijuana with 2.8% THC vs. placebo) between-subjects design, we examined the pharmacologic effect of marijuana on physiological and subjective stimulation, subjective intoxication, and self-reported negative and positive affect with 114 weekly marijuana smokers. Individuals were first tested under a baseline/no smoking condition and again under experimental condition. Relative to placebo, THC significantly increased arousal and confusion/bewilderment. However, the direction of effect on anxiety varied depending on instructional set: Anxiety increased after THC for those told placebo but decreased among other participants. Furthermore, marijuana users who expected more impairment from marijuana displayed more anxiety after smoking active marijuana, whereas those who did not expect the impairment became less anxious after marijuana. Both pharmacologic and stimulus expectancy main effects significantly increased positive affect. Frequent marijuana users were less anxious after smoking as compared to less frequent smokers. These findings show that expectancy instructions and pharmacology play independent roles in effects of marijuana on negative affect. Further studies examining how other individual difference factors impact marijuana's effects on mood are needed.

Cannabis and psychiatric disorders: it is not only addiction

Since the discovery of the endocannabinoid system, a growing body of psychiatric research has emerged focusing on the role of this system in major psychiatric disorders like schizophrenia (SCZ), bipolar disorder (BD), major depression and anxiety disorder. Continuing in the line of earlier epidemiological studies, recent replication studies indicate that frequent cannabis use doubles the risk for psychotic symptoms and SCZ. Further points of clinical research interest are alterations of endocannabinoids and their relation to symptoms as well as postmortem analyses of cannabinoid CB(1) receptor densities in SCZ. A possible neurobiological mechanism for the deleterious influence of cannabis use in SCZ has been suggested, involving the disruption of endogenous cannabinoid signaling and functioning. Even though the number of studies is still limited for affective and anxiety disorders, previous results suggest these diseases to be exciting objectives of cannabinoid-associated research. Therefore, it became apparent that cannabis use is not only frequent in patients suffering from BD, but that it also induces manic symptoms in this group. In addition, prior antipsychotic treatment decreased the numerical density of CB(1) immunoreactive glial cells in bipolar patients. Although the data on the influence of cannabis use on the development of major depression is controversial, cannabinoid compounds could display a new class of medication, as suggested by the antidepressive effects of the fatty acid amino hydrolase inhibitor URB597 in animal models. With numerous open questions and controversial results, further research is required to specify and extend the findings in this area, which provides a promising target for novel pharmacotherapeutic interventions.

Cannabinoids elicit antidepressant-like behavior and activate serotonergic neurons through the medial prefrontal cortex

Preclinical and clinical studies show that cannabis modulates mood and possesses antidepressant-like properties, mediated by the agonistic activity of cannabinoids on central CB1 receptors (CB1Rs). The action of CB1R agonists on the serotonin (5-HT) system, the major transmitter system involved in mood control and implicated in the mechanism of action of antidepressants, remains however poorly understood. In this study, we demonstrated that, at low doses, the CB1R agonist WIN55,212-2 [R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-naphthalenyl) methanone mesylate] exerts potent antidepressant-like properties in the rat forced-swim test (FST). This effect is CB1R dependent because it was blocked by the CB1R antagonist rimonabant and is 5-HT mediated because it was abolished by pretreatment with the 5-HT-depleting agent parachlorophenylalanine. Then, using in vivo electrophysiology, we showed that low doses of WIN55,212-2 dose dependently enhanced dorsal raphe nucleus 5-HT neuronal activity through a CB1R-dependent mechanism. Conversely, high doses of WIN55,212-2 were ineffective in the FST and decreased 5-HT neuronal activity through a CB1R-independent mechanism. The CB1R agonist-induced enhancement of 5-HT neuronal activity was abolished by total or medial prefrontocortical, but not by lateral prefrontocortical, transection. Furthermore, 5-HT neuronal activity was enhanced by the local microinjection of WIN55,212-2 into the ventromedial prefrontal cortex (mPFCv) but not by the local microinjection of WIN55,212-2 into the lateral prefrontal cortex. Similarly, the microinjection of WIN55,212-2 into the mPFCv produced a CB1R-dependent antidepressant-like effect in the FST. These results demonstrate that CB1R agonists possess antidepressant-like properties and modulate 5-HT neuronal activity via the mPFCv.

The endocannabinoid system as an emerging target of pharmacotherapy

The recent identification of cannabinoid receptors and their endogenous lipid ligands has triggered an exponential growth of studies exploring the endocannabinoid system and its regulatory functions in health and disease. Such studies have been greatly facilitated by the introduction of selective cannabinoid receptor antagonists and inhibitors of endocannabinoid metabolism and transport, as well as mice deficient in cannabinoid receptors or the endocannabinoid-degrading enzyme fatty acid amidohydrolase. In the past decade, the endocannabinoid system has been implicated in a growing number of physiological functions, both in the central and peripheral nervous systems and in peripheral organs. More importantly, modulating the activity of the endocannabinoid system turned out to hold therapeutic promise in a wide range of disparate diseases and pathological conditions, ranging from mood and anxiety disorders, movement disorders such as Parkinson's and Huntington's disease, neuropathic pain, multiple sclerosis and spinal cord injury, to cancer, atherosclerosis, myocardial infarction, stroke, hypertension, glaucoma, obesity/metabolic syndrome, and osteoporosis, to name just a few. An impediment to the development of cannabinoid medications has been the socially unacceptable psychoactive properties of plant-derived or synthetic agonists, mediated by CB(1) receptors. However, this problem does not arise when the therapeutic aim is achieved by treatment with a CB(1) receptor antagonist, such as in obesity, and may also be absent when the action of endocannabinoids is enhanced indirectly through blocking their metabolism or transport. The use of selective CB(2) receptor agonists, which lack psychoactive properties, could represent another promising avenue for certain conditions. The abuse potential of plant-derived cannabinoids may also be limited through the use of preparations with controlled composition and the careful selection of dose and route of administration. The growing number of preclinical studies and clinical trials with compounds that modulate the endocannabinoid system will probably result in novel therapeutic approaches in a number of diseases for which current treatments do not fully address the patients' need. Here, we provide a comprehensive overview on the current state of knowledge of the endocannabinoid system as a target of pharmacotherapy.

The acute effect of cigarette smoking on pattern visual evoked potentials

Reports of tobacco-induced electrocortical activation and decrements in ocular blood flow in the acute phase indicated that this effect is mediated via nicotine's action or neuronal systems. In this study, pattern visual evoked potentials were investigated in a group of male smokers (22 right eyes of 22 subjects) in separate real smoking and sham smoking sessions. On each session, pattern visual evoked potentials were recorded before smoking, immediately after smoking, and five minutes after smoking. Latency and amplitude values for P100 peaks were assessed and analyzed in each smoking condition for both real smoking and sham smoking sessions. Real smoking significantly decreased P100 latency values (p value related to difference between pre-smoking and immediately after smoking conditions is 0.009) and increased P100 amplitude values (p value related to difference between pre-smoking and fifth minute after smoking is 0.039). Statistically no significant difference was observed in sham smoking sessions. Our results are consistent with smoking-induced stimulant effects on pattern visual evoked potentials.

Self-administration of cannabinoids by experimental animals and human marijuana smokers

Drug self-administration behavior has been one of the most direct and productive approaches for studying the reinforcing effects of psychoactive drugs, which are critical in determining their abuse potential. Cannabinoids, which are usually abused by humans in the form of marijuana, have become the most frequently abused illicit class of drugs in the United States. The early elucidation of the structure and stereochemistry of delta-9-tetrahydrocannabinol (THC) in 1964, which is now recognized as the principal psychoactive ingredient in marijuana, activated cannabinoid research worldwide. This review examines advances in research on cannabinoid self-administration behavior by humans and laboratory animals. There have been numerous laboratory demonstrations of the reinforcing effects of cannabinoids in human subjects, but reliable self-administration of cannabinoids by laboratory animals has only recently been demonstrated. It has now been shown that strong and persistent self-administration behavior can be maintained in experimentally and drug-naïve squirrel monkeys by doses of THC comparable to those in marijuana smoke inhaled by humans. Furthermore, reinforcing effects of some synthetic CB1 cannabinoid agonists have been recently reported using intravenous and intracerebroventricular self-administration procedures in rats and mice. These findings support previous conclusions that THC has a pronounced abuse liability comparable to other drugs of abuse under certain experimental conditions. Self-administration of THC by squirrel monkeys provides the most reliable animal model for human marijuana abuse available to date. This animal model now makes it possible to study the relative abuse liability of other natural and synthetic cannabinoids and to preclinically assess new therapeutic strategies for the treatment or prevention of marijuana abuse in humans.

Cannabinoids in bipolar affective disorder: a review and discussion of their therapeutic potential

Bipolar affective disorder is often poorly controlled by prescribed drugs. Cannabis use is common in patients with this disorder and anecdotal reports suggest that some patients take it to alleviate symptoms of both mania and depression. We undertook a literature review of cannabis use by patients with bipolar disorder and of the neuropharmacological properties of cannabinoids suggesting possible therapeutic effects in this condition. No systematic studies of cannabinoids in bipolar disorder were found to exist, although some patients claim that cannabis relieves symptoms of mania and/or depression. The cannabinoids Delta(9)-tetrahydrocannabinol (THC) and cannabidiol (CBD) may exert sedative, hypnotic, anxiolytic, antidepressant, antipsychotic and anticonvulsant effects. Pure synthetic cannabinoids, such as dronabinol and nabilone and specific plant extracts containing THC, CBD, or a mixture of the two in known concentrations, are available and can be delivered sublingually. Controlled trials of these cannabinoids as adjunctive medication in bipolar disorder are now indicated.

Therapeutic potential of cannabinoids in CNS disease

The major psychoactive constituent of Cannabis sativa, delta(9)-tetrahydrocannabinol (delta(9)-THC), and endogenous cannabinoid ligands, such as anandamide, signal through G-protein-coupled cannabinoid receptors localised to regions of the brain associated with important neurological processes. Signalling is mostly inhibitory and suggests a role for cannabinoids as therapeutic agents in CNS disease where inhibition of neurotransmitter release would be beneficial. Anecdotal evidence suggests that patients with disorders such as multiple sclerosis smoke cannabis to relieve disease-related symptoms. Cannabinoids can alleviate tremor and spasticity in animal models of multiple sclerosis, and clinical trials of the use of these compounds for these symptoms are in progress. The cannabinoid nabilone is currently licensed for use as an antiemetic agent in chemotherapy-induced emesis. Evidence suggests that cannabinoids may prove useful in Parkinson's disease by inhibiting the excitotoxic neurotransmitter glutamate and counteracting oxidative damage to dopaminergic neurons. The inhibitory effect of cannabinoids on reactive oxygen species, glutamate and tumour necrosis factor suggests that they may be potent neuroprotective agents. Dexanabinol (HU-211), a synthetic cannabinoid, is currently being assessed in clinical trials for traumatic brain injury and stroke. Animal models of mechanical, thermal and noxious pain suggest that cannabinoids may be effective analgesics. Indeed, in clinical trials of postoperative and cancer pain and pain associated with spinal cord injury, cannabinoids have proven more effective than placebo but may be less effective than existing therapies. Dronabinol, a commercially available form of delta(9)-THC, has been used successfully for increasing appetite in patients with HIV wasting disease, and cannabinoid receptor antagonists may reduce obesity. Acute adverse effects following cannabis usage include sedation and anxiety. These effects are usually transient and may be less severe than those that occur with existing therapeutic agents. The use of nonpsychoactive cannabinoids such as cannabidiol and dexanabinol may allow the dissociation of unwanted psychoactive effects from potential therapeutic benefits. The existence of other cannabinoid receptors may provide novel therapeutic targets that are independent of CB(1) receptors (at which most currently available cannabinoids act) and the development of compounds that are not associated with CB(1) receptor-mediated adverse effects. Further understanding of the most appropriate route of delivery and the pharmacokinetics of agents that act via the endocannabinoid system may also reduce adverse effects and increase the efficacy of cannabinoid treatment. This review highlights recent advances in understanding of the endocannabinoid system and indicates CNS disorders that may benefit from the therapeutic effects of cannabinoid treatment. Where applicable, reference is made to ongoing clinical trials of cannabinoids to alleviate symptoms of these disorders.

Interaction between extraversion and drug-induced conditions as indicated by the contingent negative variation

The effects of chlordiazepoxide, caffeine and placebo on the contingent negative variation (CNV) in relation to extraversion were investigated in a double-blind study. Forty-four healthy naive volunteers, varying in extraversion scores, took part in the study. The baseline values of the O wave, E wave and average CNV amplitudes decreased significantly in successive experiments for individual subjects. Administration of the drugs caused a change in the amplitude of the O wave from baseline, whereas placebo effects were negligible. For chlordiazepoxide the change was positive at the lower end of the extraversion score and negative at the upper end, while for caffeine the opposite was found. For the individual drugs the correlations with the change in O wave and extraversion score were not significant (P < 0.20 in the case of both drugs). Analysis of the difference in the effect on O wave between the drug and the placebo yielded a significant negative correlation for chlordiazepoxide (P < 0.05) whereas the positive correlation for caffeine was not significant (P < 0.40). The individual differences between the effects of chlordiazepoxide and caffeine on O wave correlated significantly with the extraversion score (P < 0.02). This difference was positive at the lower end of the extraversion score and negative at the upper end. The same trend was found in the case of E wave and average amplitude but not significantly so. This finding supports the hypothesis that CNV is an indicator of the interaction between extraversion and condition.

Effects of food deprivation on subjective effects and self-administration of marijuana in humans

The effects of fasting on the intake and subjective effects of marijuana were studied in five marijuana smokers. A within-subjects design was used in which subjects smoked either active (0.8 and 3.6% THC) or placebo (0.0% THC) marijuana after eating normally or after fasting for 24 hr. Six experimental sessions were conducted in a randomized order. Each 3-hr. session consisted of two periods: a sampling period in which subjects took 4 controlled puffs from a cigarette of a given potency, followed about one hour later by a 30-min. self-administration period, in which subjects could smoke as much or as little of the sampled marijuana as desired. Subjective and physiological measures (i.e., carbon monoxide level and heart rate) were assessed before and 5, 20, and 60 min. after the four puffs during the sampling period. During the self-administration period, the number of puffs taken was recorded. Dose-dependent effects of marijuana, such as elevated heart rate and "high" ratings, were observed during the sampling period, but these effects of marijuana were not affected by the feeding manipulation. Subjects varied widely in their marijuana self-administration, but self-administration was not systematically affected by fasting. We conclude that an acute period of food deprivation does not affect the mood-altering effects of different potencies of marijuana. We could not adequately demonstrate whether fasting increases the reinforcing efficacy of marijuana, since self-administration rate of active marijuana did not exceed that of placebo marijuana self-administration.

Salivary THC following cannabis smoking correlates with subjective intoxication and heart rate

A cannabis smoking trial was conducted using paid volunteers. Subjective intoxication, measured using a visual analogue scale, was compared with heart rate and with salivary delta-9-tetrahydrocannabinol (THC) levels at various times after smoking a cigarette containing 11 mg THC. Subjective intoxication and heart rate elevation were significantly correlated with the log of salivary THC. Salivary THC levels are a sensitive index of recent cannabis smoking, and appear more closely linked with the effects of intoxication than do either blood or urine cannabinoid levels.

Delta-9-tetrahydrocannabinol content and human marijuana self-administration

The role of marijuana delta-9-tetrahydrocannabinol (THC) content in controlling marijuana smoking behavior was examined in ten regular marijuana smokers. Each subject was allowed to self-administer marijuana of low, medium or high THC content freely over a 30-min period. Each potency of marijuana was color coded, and subjects smoked each potency on five separate occasions to provide the opportunity for them to learn from prior exposures the relative potencies of each marijuana type. Total intake of marijuana smoke during each session was estimated by measuring the post-smoking increase in expired air carbon monoxide (CO) level. Measures of marijuana effect included heart rate and standardized subjective effects scales. There were no differences among the three potencies of marijuana in post-smoking CO boost, and all measures that were sensitive to marijuana showed a clear dose response. Tolerance was observed over the course of the study to the heart-rate increasing effect of marijuana. These results indicate that subjects failed to regulate their intake of marijuana smoke in response to substantial (4-fold) changes in marijuana THC content.

Cortical evoked potentials and clinical rating scales as measures of depressive illness

Relationships between clinical ratings and cortical evoked potentials were examined before and during antidepressant drug treatment in 32 patients with major depressive disorder (DSM-III). Clinical rating scales included Hamilton Rating Scale for Depression, Beck Depression Inventory, Present State Examination (PSE) and Newcastle Scale. Evoked potentials included contingent negative variation (CNV), post-imperative negative variation (PINV) and auditory evoked potential (AEP) There were close correlations between all rating scales, and factor analysis produced only one component, suggesting that the common variance between them related to severity of depression. CNV magnitude before treatment correlated negatively with severity of depression regardless of diagnostic category. Depressed patients had a prominent PINV which persisted during antidepressant treatment. The amplitude of late components (N1P2) of the AEP was reduced strikingly in patients with a history of suicide attempts.

Effects of cigarette smoking on resting EEG, visual evoked potentials and photic driving

The effects of smoking a cigarette (1.3 mg nicotine delivery) versus sham smoking were studied using EEG, visual evoked potentials (VEP), photic driving (PD) and heart rate (HR) in thirty young healthy male and female habitual cigarette smokers. Heart rate (HR) and exhaled carbon monoxide (CO) level were significantly increased by real as opposed to sham smoking. Real versus sham smoking significantly increased relative power in the beta bands, reduced alpha and theta activity to a small but significant extent, but had no effect on delta activity. Dominant EEG alpha frequency was significantly increased by real as opposed to sham smoking. Smoking produced no significant mean change in PD or VEP. However, correlational analysis indicated that variables such as basal CO level, residual butt filter nicotine, basal electrocortical response level and personality, predicted to varying degrees the magnitude and direction of the effect of smoking on VEP, PD and EEG.

Delta-9-tetrahydrocannabinol and gastric emptying

The effects of delta-9-tetrahydrocannabinol (0.5 and 1 mg i.v.) on gastric emptying of liquid were investigated in seven normal volunteers and compared with placebo. Despite significant change in pulse rate and psychological parameters consistent with cannabis activity there was no significant effect on the pattern of gastric emptying. It is therefore suggested that an anti-emetic action of delta-9-tetrahydrocannabinol does not involve a change in gastric emptying.