First positive reactions to cannabis constitute a priority risk factor for cannabis dependence

Evidence for sex differences in the impact of cytochrome P450 genotypes on early subjective effects of cannabis

Early positive subjective effects of cannabis predict the development of cannabis use disorder (CUD). Genetic factors, such as the presence of cytochrome P450 genetic variants that are associated with reduced Δ9-tetrahydrocannabinol (THC) metabolism, may contribute to individual differences in subjective effects of cannabis. Young adults (N = 54) with CUD or a non-CUD substance use disorder (control) provided a blood sample for DNA analysis and self-reported their early (i.e., effects upon initial uses) and past-year positive and negative subjective cannabis effects. Participants were classified as slow metabolizers if they had at least one CYP2C9 or CYP3A4 allele associated with reduced activity. Though the CUD group and control group did not differ in terms of metabolizer status, slow metabolizer status was more prevalent among females in the CUD group than females in the control group. Slow metabolizers reported greater past year negative THC effects compared to normal metabolizers; however, slow metabolizer status did not predict early subjective cannabis effects (positive or negative) or past year positive effects. Post-hoc analyses suggested males who were slow metabolizers reported more negative early subjective effects of cannabis than female slow metabolizers. Other sex-by-genotype interactions were not significant. These initial findings suggest that genetic variation in CYP2C9 and CYP3A4 may have sex-specific associations with cannabis-related outcomes. Slow metabolizer genes may serve as a risk factor for CUD for females independent of subjective effects. Male slow metabolizers may instead be particularly susceptible to the negative subjective effects of cannabis.

The effects of simultaneous alcohol and cannabis use on subjective drug effects: A narrative review across methodologies

Over 75% of young adults who use cannabis also report drinking alcohol, leading to increased risks that include impaired cognition, substance use disorders, and more heavy and frequent substance use. Studies suggest that subjective responses to either alcohol or cannabis can serve as a valuable indicator for identifying individuals at risk of prolonged substance use and use disorder. While laboratory studies show additive effects when alcohol and cannabis are used together, the impact of co-using these substances, specifically with respect to cannabidiol, on an individual's subjective experience remains unclear. This narrative review explores the effects of simultaneous alcohol and cannabis (SAM) use on subjective drug effects, drawing from qualitative research, laboratory experiments, and naturalistic studies. Experimental findings are inconsistent regarding the combined effects of alcohol and cannabis, likely influenced by factors such as dosage, method of administration, and individual substance use histories. Similarly, findings from qualitative and naturalistic studies are mixed regarding subjective drug effects following SAM use. These discrepancies may be due to recall biases, variations in assessment methods, and the measurement in real-world contexts of patterns of SAM use and related experiences. Overall, this narrative review highlights the need for more comprehensive research to understand more fully subjective drug effects of SAM use in diverse populations and settings, emphasizing the importance of frequent and nuanced assessment of SAM use and subjective responses in naturalistic settings.

Subjective effects as predictors of substance use disorders in a clinical sample: A longitudinal study

BACKGROUND

The literature on the association between subjective effects (SEs; i.e., how an individual perceives their physiological and psychological reactions to a drug) and substance use disorders (SUDs) is largely limited to community samples. The present study addressed the following aims in a clinical sample: whether SEs predict general versus substance-specific SUD in adolescence and adulthood after controlling for conduct disorder symptoms (CDsymp); whether SEs predict SUDs across drug classes; whether SEs predict change in SUD from adolescence to adulthood; and whether there are racial/ethnic differences in associations.

METHODS

Longitudinal analyses were conducted using data from a sample of 744 clinical probands recruited from residential and outpatient SUD treatment facilities in CO during adolescence (Mage = 16.26) and re-assessed twice in adulthood (Mages = 22.56 and 28.96), approximately seven and twelve years after first assessment. SEs and CDsymp were assessed in adolescence. SUD severity was assessed at adolescence and twice during adulthood.

RESULTS

SEs assessed in adolescence robustly predicted general SUD for legal and illegal substances in adolescence and adulthood, whereas CDsymp predicted SUD primarily in adolescence. Higher positive and negative SEs in adolescence were associated with greater SUD severity after controlling for CDsymp, with similar magnitudes. Results indicated cross-substance effects of SEs on SUD. We found no evidence for racial/ethnic differences in associations.

CONCLUSIONS

We investigated the progression of SUD in a high-risk sample with greater odds of sustained SUD. In contrast to CDsymp, both positive and negative SEs consistently predicted general SUD across substances in adolescence and adulthood.

Combining noninvasive brain stimulation with behavioral pharmacology methods to study mechanisms of substance use disorder

Psychotropic drugs and transcranial magnetic stimulation (TMS) are effective for treating certain psychiatric conditions. Drugs and TMS have also been used as tools to explore the relationship between brain function and behavior in humans. Combining centrally acting drugs and TMS has proven useful for characterizing the neural basis of movement. This combined intervention approach also holds promise for improving our understanding of the mechanisms underlying disordered behavior associated with psychiatric conditions, including addiction, though challenges exist. For example, altered neocortical function has been implicated in substance use disorder, but the relationship between acute neuromodulation of neocortex with TMS and direct effects on addiction-related behaviors is not well established. We propose that the combination of human behavioral pharmacology methods with TMS can be leveraged to help establish these links. This perspective article describes an ongoing study that combines the administration of delta-9-tetrahydrocannabinol (THC), the main psychoactive compound in cannabis, with neuroimaging-guided TMS in individuals with problematic cannabis use. The study examines the impact of the left dorsolateral prefrontal cortex (DLPFC) stimulation on cognitive outcomes impacted by THC intoxication, including the subjective response to THC and the impairing effects of THC on behavioral performance. A framework for integrating TMS with human behavioral pharmacology methods, along with key details of the study design, are presented. We also discuss challenges, alternatives, and future directions.

Predictive impact of different acute cannabis intoxication effects with regard to abstinence motivation and cessation of use

Cannabis use is a common risk factor for psychoses. But although prevalence of consumption as well as potency of cannabis increased, the incidence of schizophrenia remained stable. The discontinuation hypothesis suggests that a potential increase of psychoses incidence may be relativized by more frequent cessation of consumption due to higher rates of adverse psychosis-like intoxication effects (PLE), caused by stronger cannabis. A mixed methods online survey was administered to 441 current and past users to analyze the predictive impact of different acute intoxication effects regarding abstinence motivation/cessation of use. Our hypothesis was that PLE would be experienced as the most aversive intoxication effect and therefore have the highest predictive significance. Possible confounds were included (craving, patterns of consumption and sociodemographics). Further analyzes compared past versus current users regarding the quality of intoxication effects, suggesting that past users retrospectively experienced more unpleasant experiences than current users. Free-text data explored subjective reasons for abstinence. We found that paranoid/dysphoric intoxication effects were most predictive for abstinence motivation. Less predictive were psychosis-like intoxication effects such as hallucinations. Group comparisons revealed significant more unpleasurable and less positive intoxication effects in past users compared with current users. Current users with the intention to stop consumption showed significantly more paranoia/dysphoria intoxication compared to users with no intention to stop use. As a conclusion, different intoxication experiences have different effects on abstinence motivation and substance use behavior. They therefore provide a focus that should be increasingly integrated into treatment concepts.

Influence of Cannabinoid Receptor 1 Genetic Variants on the Subjective Effects of Smoked Cannabis

As many jurisdictions consider relaxing cannabis legislation and usage is increasing in North America and other parts of the world, there is a need to explore the possible genetic differences underlying the subjective effects of cannabis. This pilot study investigated specific genetic variations within the cannabinoid receptor 1 (CNR1) gene for association with the subjective effects of smoked cannabis. Data were obtained from a double-blinded, placebo-controlled clinical trial studying the impact of cannabis intoxication on driving performance. Participants randomized to the active cannabis group who consented to secondary genetic analysis (n = 52) were genotyped at the CNR1 rs1049353 and rs2023239 polymorphic areas. Maximum value and area under the curve (AUC) analyses were performed on subjective measures data. Analysis of subjective effects by genotype uncovered a global trend towards greater subjective effects for rs1049353 T-allele- and rs2023239 C-allele-carrying subjects. However, significant differences attributed to allelic identity were only documented for a subset of subjective effects. Our findings suggest that rs1049353 and rs2023239 minor allele carriers experience augmented subjective effects during acute cannabis intoxication.

What is the prevalence and risk of cannabis use disorders among people who use cannabis? a systematic review and meta-analysis

BACKGROUND AND AIMS

We aim to quantify the prevalence and risk of having a cannabis use disorder (CUD), cannabis abuse (CA) or cannabis dependence (CD) among people in the general population who have used cannabis.

METHOD

We conducted a systematic review of epidemiological cross-sectional and longitudinal studies on the prevalence and risks of CUDs among cannabis users. We identified studies published between 2009 and 2019 through PubMed, the Global Burden Disease (GBD) Database, and supplementary searches up to 2020. The outcomes of interest were CUDs based on DSM or ICD criteria. Estimates were synthesized using random-effects meta-analyses, followed by meta-regression of study characteristics on effect sizes.

RESULTS

From 1383 records identified, 21 studies were included. Meta-analyses showed that among people who used cannabis, 22% (18-26%) have CUD, 13% (8-18%) have CA, and 13% (10-15%) have CD. Estimates from cohort studies, showed that the risk of developing CD increased to 33% (22-44%) among young people who engaged in regular (weekly or daily) use of cannabis. There was a lack of data from cohort studies to estimate the risk of CUD or CA among regular cannabis users.

CONCLUSIONS

Cannabis users need to be informed about the risks of developing CUDs and the higher risks among those who initiate early and use frequently during adolescence. Future studies are needed to examine how changes in cannabis policies may affect the risks of CUDs in the population.

Assessment of Acute Motor Effects and Tolerance Following Self-Administration of Alcohol and Edible ∆9 -Tetrahydrocannabinol in Adolescent Male Mice

BACKGROUND

Cannabinoids and their principle psychoactive target, the cannabinoid type 1 receptor (CB1R), impact a number of alcohol-related properties, and although alcohol and cannabis are often co-used, particularly in adolescence, few animal models of this phenomenon exist. We modeled the co-use of alcohol and ∆⁹ -tetrahydrocannabinol (THC) in adolescent mice using ingestive methods popular during this developmental period in humans, namely binge-drinking and edible THC. With this model, we assessed levels of use, acute effects, and tolerance to each substance.

METHODS

Adolescent male C57BL/6J mice had daily, limited access to 1 of 2 edible doughs (THC or control), to 1 of 2 fluids (ethanol (EtOH) or water), and in 1 of 2 orders (dough-fluid or fluid-dough). Home cage locomotor activity was recorded both during access and after access. On the day following the final access session, a subset of mice were assessed for functional and metabolic tolerance to alcohol using accelerating rotarod and blood EtOH concentrations, respectively. The remaining mice were assessed for tolerance to THC-induced hypothermia, and whole-brain CB1R expression was assessed in all mice.

RESULTS

EtOH intake was on par with levels previously reported in adolescent mice. Edible THC was well-consumed, but consumption decreased at the highest dose provided. Locomotor activity increased following EtOH intake and decreased following edible THC consumption, and edible THC increased fluid intake in general. The use of alcohol produced neither functional nor metabolic tolerance to an alcohol challenge. However, the use of edible THC impaired subsequent drug-free rotarod performance and was associated with a reduction in THC's hypothermic effect.

CONCLUSIONS

Adolescent mice self-administered both alcohol and edible THC to a degree sufficient to acutely impact locomotor activity. However, only edible THC consumption had lasting effects during short-term abstinence. Thus, this adolescent co-use model could be used to explore sex differences in self-administration and the impact substance co-use might have on other domains such as mood and cognition.

Psychotic-like experiences with cannabis use predict cannabis cessation and desire to quit: a cannabis discontinuation hypothesis

BACKGROUND

Evidence suggests that cannabis-induced psychotic-like experiences may be a marker of psychosis proneness. The effect of such experiences on cannabis use has not systematically been examined.

METHODS

We undertook a mixed-methods online survey of 1231 cannabis users (including 926 continued users) using the Cannabis Experiences Questionnaire. We examined the effect of psychotic-like and pleasurable experiences on cessation of cannabis and intention to quit. Socio-demographic variables, cannabis use parameters and substance misuse history were included as covariates. Free-text data explored subjective reasons for changes in use.

RESULTS

Cessation of cannabis use was associated with greater psychotic-like experiences [p < 0.001, Exp(B) 1.262, 95% confidence interval (CI) 1.179-1.351], whilst continued cannabis users were more likely to report pleasurable experiences [p < 0.001, Exp(B) 0.717, 95% CI 0.662-0.776]. Intention to quit cannabis in continued users was associated with greater psychotic-like experiences [p < 0.003, Exp(B) 1.131, 95% CI 1.044-1.225], whilst intention to not quit was significantly associated with increased pleasurable experiences [p < 0.015, Exp(B) 0.892, 95% CI 0.814-0.978]. Whereas former users clearly ascribed cessation to negative experiences, continued users who expressed intention to quit less readily ascribed the intention to negative experiences.

CONCLUSIONS

Elucidation of psychotic-like experiences may form the basis of a therapeutic intervention for those who wish to quit. Cessation in those with cannabis-induced psychotomimetic experiences may offset the risk for the development of a psychotic disorder, in this higher risk group.

Relevance of treated cocaine users' retrospective memory of first cocaine use

Little is known regarding between-subject variability in the subjective effects of first cocaine use. This study retrospectively assesses the subjective effects of first cocaine use in 160 current treatment-seeking cocaine use disorder patients. Subjective effects of first cocaine use were evaluated with an ad-hoc questionnaire used for cannabis effects. A principal component analysis (PCA) was performed, with resulting factors correlated with clinical variables (α = 0.05). Four factors emerged in the PCA, namely Anxiety (accounting for 21.5% of questionnaire variance), Disinhibition (17.3%), Tachypsychia (16%) and Calmness (13%). Male gender was associated with Disinhibition and Tachypsychia. Cocaine severity factors were associated with Disinhibition, Tachypsychia and Calmness. Opiate, sedative and poppers uses were associated with Anxiety, Tachypsychia and Calmness. The retrospective assessment of the subjective effects of first cocaine use shows significant variability. The different dimensions of subjective first effects are influenced by age, gender and previous substance use history, as well as characteristics of first cocaine use and cocaine-related outcomes.

Mood Fluctuation and Psychobiological Instability: The Same Core Functions Are Disrupted by Novel Psychoactive Substances and Established Recreational Drugs

Many novel psychoactive substances (NPS) have entered the recreational drug scene in recent years, yet the problems they cause are similar to those found with established drugs. This article will debate the psychobiological effects of these newer and more traditional substances. It will show how they disrupt the same core psychobiological functions, so damaging well-being in similar ways. Every psychoactive drug causes mood states to fluctuate. Users feel better on-drug, then feel worse off-drug. The strength of these mood fluctuations is closely related to their addiction potential. Cyclical changes can occur with many other core psychobiological functions, such as information processing and psychomotor speed. Hence the list of drug-related impairments can include: homeostatic imbalance, HPA axis disruption, increased stress, altered sleep patterns, neurohormonal changes, modified brain rhythms, neurocognitive impairments, and greater psychiatric vulnerability. Similar patterns of deficit are found with older drugs such as cocaine, nicotine and cannabis, and newer substances such as 3,4-methylenedioxymethamphetamine (MDMA), mephedrone and spice. All psychoactive drugs damage human well-being through similar basic neuropsychobiological mechanisms.

Development and validation of the cannabis experiences questionnaire - Intoxication effects checklist (CEQ-I) short form

OBJECTIVE

To develop and validate a short form of the Cannabis Experiences Questionnaire - Intoxication Effects (CEQ-I), a 42-item scale which measures the euphoric and paranoid-dysphoric effects of cannabis intoxication.

METHOD

Exploratory and confirmatory factor analyses were conducted among 604 past-month cannabis users to develop the short form. The factor structure was replicated in a second sample of 146 past-month cannabis users. The concurrent validity of the scale was also examined.

RESULTS

Consistent with previous research, two factors were identified (paranoid-dysphoric; euphoric), and were replicated with confirmatory factor analyses. The most parsimonious scale consisted of 13 items. Correlations of short-form subscales with corresponding original subscales were high. The paranoid-dysphoric subscale was also moderately positively correlated with measures of psychotic-like experiences (PLEs) and psychological distress.

CONCLUSIONS

The revised and validated CEQ-I short form can be used to explore the euphoric and paranoid-dysphoric effects of cannabis intoxication in young cannabis users, and whether these experiences increase their risk of developing cannabis use and psychotic disorders. The CEQ-I short form has the potential to aid in the identification of young cannabis users at risk of the paranoid-dysphoric effects of cannabis intoxication and may assist in the development of early intervention strategies targeting cannabis users with PLEs.

Cdh13 and AdipoQ gene knockout alter instrumental and Pavlovian drug conditioning

Genome-wide association studies in humans have suggested that variants of the cadherin-13 (CDH13) gene are associated with substance use disorder, subjective response to amphetamine, and attention deficit hyperactivity disorder. To examine the role of the Cdh13 and its peptide ligand adiponectin (AdipoQ) in addiction-related behaviors, we assessed Cdh13 knockout (KO) rats and AdipoQ KO mice using intravenous cocaine self-administration and conditioned place preference (CPP) paradigms. During intravenous cocaine self-administration, male Cdh13 heterozygous (+/-) and KO (-/-) rats showed increased cue-induced reinstatement compared with wild-type (WT) rats when presented with a cocaine-paired stimulus, whereas female Cdh13 rats showed no differences across genotype. Cdh13 -/- rats showed higher responding for a saccharin reinforcer and learned the choice reaction time (RT) task more slowly than WTs. However, we found no differences between Cdh13 -/- and +/+ rats in responding for sensory reinforcement, number of premature responses in the RT task, tendency to approach a Pavlovian food cue, CPP and locomotor activation to cocaine (10 or 20 mg/kg). In AdipoQ -/- mice, there was a significant increase in CPP to methamphetamine (1 mg/kg) but not to a range of d-amphetamine doses (0.5, 1, 2 and 4 mg/kg). Taken together, these data suggest that Cdh13 and AdipoQ regulate sensitivity to psychomotor stimulants and palatable rewards without producing major changes in other behaviors. In humans, these two genes may regulate sensitivity to natural and drug rewards, thus influencing susceptibility to the conditioned drug effects and relapse.

Recreational stimulants, herbal, and spice cannabis: The core psychobiological processes that underlie their damaging effects

AIMS

Recreational drugs are taken for their positive mood effects, yet their regular usage damages well-being. The psychobiological mechanisms underlying these damaging effects will be debated.

METHODS

The empirical literature on recreational cannabinoids and stimulant drugs is reviewed. A theoretical explanation for how they cause similar types of damage is outlined.

RESULTS

All psychoactive drugs cause moods and psychological states to fluctuate. The acute mood gains underlie their recreational usage, while the mood deficits on withdrawal explain their addictiveness. Cyclical mood changes are found with every central nervous system stimulant and also occur with cannabis. These mood state changes provide a surface index for more profound psychobiological fluctuations. Homeostatic balance is altered, with repetitive disturbances of the hypothalamic-pituitary-adrenal axis, and disrupted cortisol-neurohormonal secretions. Hence, these drugs cause increased stress, disturbed sleep, neurocognitive impairments, altered brain activity, and psychiatric vulnerability. Equivalent deficits occur with novel psychoactive stimulants such as mephedrone and artificial "spice" cannabinoids. These psychobiological fluctuations underlie drug dependency and make cessation difficult. Psychobiological stability and homeostatic balance are optimally restored by quitting psychoactive drugs.

CONCLUSIONS

Recreational stimulants such as cocaine or MDMA (3.4-methylenedioxymethamphetamine) and sedative drugs such as cannabis damage human homeostasis and well-being through similar core psychobiological mechanisms.

A Preliminary Investigation of Individual Differences in Subjective Responses to D-Amphetamine, Alcohol, and Delta-9-Tetrahydrocannabinol Using a Within-Subjects Randomized Trial

Polydrug use is common, and might occur because certain individuals experience positive effects from several different drugs during early stages of use. This study examined individual differences in subjective responses to single oral doses of d-amphetamine, alcohol, and delta-9-tetrahydrocannabinol (THC) in healthy social drinkers. Each of these drugs produces feelings of well-being in at least some individuals, and we hypothesized that subjective responses to these drugs would be positively correlated. We also examined participants’ drug responses in relation to personality traits associated with drug use. In this initial, exploratory study, 24 healthy, light drug users (12 male, 12 female), aged 21–31 years, participated in a fully within-subject, randomized, counterbalanced design with six 5.5-hour sessions in which they received d-amphetamine (20mg), alcohol (0.8 g/kg), or THC (7.5 mg), each paired with a placebo session. Participants rated the drugs’ effects on both global measures (e.g. feeling a drug effect at all) and drug-specific measures. In general, participants’ responses to the three drugs were unrelated. Unexpectedly, “wanting more” alcohol was inversely correlated with “wanting more” THC. Additionally, in women, but not in men, “disliking” alcohol was negatively correlated with “disliking” THC. Positive alcohol and amphetamine responses were related, but only in individuals who experienced a stimulant effect of alcohol. Finally, high trait constraint (or lack of impulsivity) was associated with lower reports of liking alcohol. No personality traits predicted responses across multiple drug types. Generally, these findings do not support the idea that certain individuals experience greater positive effects across multiple drug classes, but instead provide some evidence for a “drug of choice” model, in which individuals respond positively to certain classes of drugs that share similar subjective effects, and dislike other types of drugs.

Parental contributions and separation anxiety on adolescents' cannabis use: a preliminary study based on French high school students

BACKGROUND

Separation anxiety (SA) among adolescents remains a very rare diagnosis. According to some authors, behavioral disorders may arise from SA disorders. This study evaluated the relationship between cannabis use and family functioning among adolescent cannabis users.

METHOD

Adolescents (n = 336) completed questionnaires about the frequency of their cannabis use, SA symptoms in adult populations, dysfunctional separation-individuation processes in early adolescence, parental types as perceived by the children, and depression symptoms.

RESULTS

Adolescent users of cannabis obtained significantly higher scores than adolescent nonusers of cannabis on the Anxiety Separation Adulthood scale (p < .005) and lower scores on the "care" subscale about parents' representations ("mother," p < .01; "father," p < .001). The logistic regression analysis indicated that SA disorders and care significantly encouraged cannabis use.

DISCUSSION

Among adolescents, cannabis use is perceived as a solution that reduces the intolerable feelings of SA disorder. If successful separation-individuation allows autonomy, the results indicate that cannabis use hides individuation problems. The use of this substance allows adolescents to express their personality and differentiate themselves from others through marginal behavior.

Impact of age at onset of cannabis use on cannabis dependence and driving under the influence in the United States

BACKGROUND AND AIMS

There is growing evidence that driving under the influence of cannabis is associated with a higher risk of motor vehicle crash. Cannabis dependence has been reported to be associated with a three-fold increased risk of motor vehicle crash. The impact of the age at onset of cannabis use on the risk of both cannabis dependence and driving under the influence of cannabis has not been evaluated so far.

METHODS

Data were drawn from the 2001-2002 National Epidemiological Survey on Alcohol and Related Conditions (NESARC), a survey of 43,093 adults aged 18 years and older. We limited our analyses to the sample of participants who reported having ever used cannabis (n=8172), of whom 8068 had a known age at onset of cannabis use.

RESULTS

Of the 8068 participants included, 5.15% reported having driven under the influence of cannabis. Among those, only a minority (14.46%) were diagnosed with cannabis dependence. Compared to those who start using cannabis at age 21 years or after, participants who used cannabis before the age of 14 years were 4 times more likely to have a history of cannabis dependence and 3 times more likely to reported having driven under the influence of cannabis. An inverse relationship between the age at onset of cannabis use and driving under the influence and risk of cannabis dependence was found.

CONCLUSIONS

Starting to smoke cannabis younger than 21 years is associated with both cannabis dependence and driving under the influence of cannabis.

Evaluating the role of a galanin enhancer genotype on a range of metabolic, depressive and addictive phenotypes

There is a large body of pre-clinical and some clinical data to link the neuropeptide galanin to a range of physiological and pathological functions that include metabolism, depression, and addiction. An enhancer region upstream of the human GAL transcriptional start site has previously been characterised. In-vitro transfection studies in rat hypothalamic neurons demonstrated that the CA allele was 40% less active than the GG allele in driving galanin expression. Our hypothesis was to investigate the effect of this galanin enhancer genotype on a range of variables that relate to the known functions of the galaninergic system in the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort of young adults (N = 169-6,078). Initial findings showed a positive relationship of cannabis usage (OR = 2.070, P = 0.007, N = 406 (individuals who had used cannabis at least once within the last 12 months, total sample size 2731) with the GG haplotype, consistent with the previous published data linking galanin with an increased release of dopamine. As our sample size was relatively small we replicated the analysis in a larger cohort of 2,224 African Americans and 1,840 European Americans, but no discernible trend across genotypes was observed for the relationship with cannabis usage. Further, we found no association of the galanin enhancer genotype with any of the other pathophysiological parameters measured. These findings emphasise that preclinical data does not always predict clinical outcomes in cohort studies, noting that association studies are subject to multiple confounders.

Gender differences in prevalence of substance use disorders among individuals with lifetime exposure to substances: results from a large representative sample

BACKGROUND AND OBJECTIVES

Research regarding substance use and substance use disorders (SUDs) shows significant gender differences in prevalence of substance use and dependence. Though lifetime exposure to substances is higher among males, previous reports have not regarded gender differences in prevalence of SUDs among individuals formerly exposed to substances. In addition, though substance abuse is particularly important when exploring gender differences, previous reports have largely focused on rates of transition to substance dependence alone. In this study, we explored gender differences in prevalence of SUDs among individuals with lifetime exposure to substances using a single diagnostic category (abuse or dependence).

METHODS

We analyzed 11 different categories of substances: heroin, cocaine, cannabis, nicotine, alcohol, hallucinogens, inhalants, sedatives, tranquilizers, opioids, and amphetamines. Data were derived from the National Epidemiologic Survey on Alcohol and Related Conditions (Wave 1, n = 43,093). The impact of gender on prevalence of SUDs among individuals with lifetime exposure to substances was assessed with odds ratios (ORs) using logistic regressions and adjusted for socio-demographic factors.

RESULTS

Our results show that among individuals with lifetime exposure to substances, males had a significantly higher prevalence of alcohol (OR = 2.95), sedatives (OR = 2.00), cannabis (OR = 1.93), tranquilizers (OR = 1.64), opioids (OR = 1.54), hallucinogens (OR = 1.31), and cocaine (OR = 1.26) use disorders compared with females.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Using a single broad diagnostic category highlights gender differences in the prevalence of SUDs among individuals with former exposure to substances. Specifically, the significant gender differences found for alcohol, sedatives, and cannabis use disorders may be important for tailoring preventive measures targeted at reducing rates of SUDs among males using these substances.

An Examination of Marijuana Use Among a Vulnerable Population in Canada

OBJECTIVES

Although the perceived risk of cannabis has decreased over the last few years, the contribution of marijuana use to the burden of disease on society is significant. Globally, Indigenous peoples have rates of marijuana use that are significantly higher than that of the general population. Understanding patterns of use is fundamental to developing appropriate policy and programming strategies to improve health and well-being.

METHODS

This study examined the characteristics of respondents who had ever been frequent marijuana users (used more than once a week), among a cross-sectional sample of 340 people, aged 18 and over, from Kettle and Stony Point First Nation in Ontario, Canada. The research incorporated Aboriginal-specific measures, examining issues related to colonialism and racism. Logistic regression models were used to assess the extent that sociodemographic variables, body mass index, mental health (depression, anxiety), licit substance use (alcohol and tobacco), Historical Loss Scale, Childhood Trauma Scale, and Measure of Indigenous Racism Experience (MIRE) Interpersonal Racism Scale predicted ever having been a frequent marijuana user.

RESULTS

Aboriginal-specific issues were not associated with marijuana use nor was marijuana use related to depression or anxiety. However, ever engaging in frequent marijuana use was reported by more than half of the sample and associated with being younger, male, and a smoker.

CONCLUSIONS

The high prevalence of frequent marijuana use (53.2 %) suggests normalization of the substance that may indicate a potentially large public health problem.

Do early experiences with cannabis vary in cigarette smokers?

INTRODUCTION

We examine whether regular cigarette smokers were more likely to be exposed to and use cannabis at an earlier age, and further, upon initiation, whether their initial experiences with cannabis varied from those reported by never/non-regular cigarette smokers.

METHOD

A sample of 3797 Australian twins and siblings aged 21-46 years was used. Survival analyses examined whether cigarette smokers were at increased likelihood of early opportunity to use cannabis and early onset of cannabis use. Logistic regression examined whether cigarette smokers reported greater enjoyment of their cannabis experience, inhaling on the first try, differing positive and negative initial subjective reactions, smoked cigarettes with cannabis the first time and were more likely to try cannabis again within a week.

RESULTS

Regular cigarette smokers were more likely to report an earlier opportunity to use cannabis and early onset of cannabis use. Regular cigarette smokers were also considerably more likely to have enjoyed their first experience with cannabis and reported higher rates of positive initial reactions. They were more likely to report inhaling on the first try and smoking cigarettes with cannabis. Potentially negative subjective reactions were also elevated in regular cigarette smokers. Importantly, cigarette smokers were at 1.87 increased odds of smoking cannabis within a week of their initial use.

CONCLUSION

These findings indicate that the well-known overlap in cannabis and cigarette smoking behaviors may evolve as early as opportunity to use and extend through the course of the substance use trajectory.

Genome-wide association study of d-amphetamine response in healthy volunteers identifies putative associations, including cadherin 13 (CDH13)

Both the subjective response to d-amphetamine and the risk for amphetamine addiction are known to be heritable traits. Because subjective responses to drugs may predict drug addiction, identifying alleles that influence acute response may also provide insight into the genetic risk factors for drug abuse. We performed a Genome Wide Association Study (GWAS) for the subjective responses to amphetamine in 381 non-drug abusing healthy volunteers. Responses to amphetamine were measured using a double-blind, placebo-controlled, within-subjects design. We used sparse factor analysis to reduce the dimensionality of the data to ten factors. We identified several putative associations; the strongest was between a positive subjective drug-response factor and a SNP (rs3784943) in the 8(th) intron of cadherin 13 (CDH13; P = 4.58×10(-8)), a gene previously associated with a number of psychiatric traits including methamphetamine dependence. Additionally, we observed a putative association between a factor representing the degree of positive affect at baseline and a SNP (rs472402) in the 1(st) intron of steroid-5-alpha-reductase-α-polypeptide-1 (SRD5A1; P = 2.53×10(-7)), a gene whose protein product catalyzes the rate-limiting step in synthesis of the neurosteroid allopregnanolone. This SNP belongs to an LD-block that has been previously associated with the expression of SRD5A1 and differences in SRD5A1 enzymatic activity. The purpose of this study was to begin to explore the genetic basis of subjective responses to stimulant drugs using a GWAS approach in a modestly sized sample. Our approach provides a case study for analysis of high-dimensional intermediate pharmacogenomic phenotypes, which may be more tractable than clinical diagnoses.

Do initial responses to drugs predict future use or abuse?

Individuals vary in their initial reactions to drugs of abuse in ways that may contribute to the likelihood of subsequent drug use. In humans, most drugs of abuse produce positive subjective states such as euphoria and feelings of well-being, which may facilitate repeated use. In nonhumans, many drugs initially increase locomotor activity and produce discriminative stimulus effects, both of which have been considered to be models of human stimulant and subjective states. Both humans and nonhumans vary in their sensitivity to early acute drug effects in ways that may predict future use or self-administration, and some of these variations appear to be genetic in origin. However, it is not known exactly how the initial responses to drugs in either humans or nonhumans relate to subsequent use or abuse. In humans, positive effects of drugs facilitate continued use of a drug while negative effects discourage use, and in nonhumans, greater genetic risk for drug intake is predicted by reduced sensitivity to drug aversive effects; but whether these initial responses affect escalation of drug use, and the development of dependence is currently unknown. Although early use of a drug is a necessary step in the progression to abuse and dependence, other variables may be of greater importance in the transition from use to abuse. Alternatively, the same variables that predict initial acute drug effects and early use may significantly contribute to continued use, escalation and dependence. Here we review the existing evidence for relations between initial direct drug effects, early use, and continued use. Ultimately, these relations can only be determined from systematic longitudinal studies with comprehensive assessments from early drug responses to progression of problem drug use. In parallel, additional investigation of initial responses in animal models as predictors of drug use will shed light on the underlying mechanisms.

Subjective effects for alcohol, tobacco, and marijuana association with cross-drug outcomes

METHODS

The cross-drug relationship of subjective experiences between alcohol, tobacco, and marijuana and problem drug use behaviors were examined. Data were drawn from 3853 individuals between the ages of 11 and 30 years of age participating in the Colorado Center on Antisocial Drug Dependence [CADD]. Subjective experiences were assessed using a 13-item questionnaire that included positive and negative responses for alcohol, tobacco, and marijuana. Lifetime abuse and dependence on these three drugs was assessed using the Composite International Diagnostic Interview, Substance Abuse Module [CIDI-SAM].

RESULTS

Positive and negative subjective experience scales were similar for alcohol, tobacco, and marijuana, although the hierarchical ordering of items differed by drug. Subjective experience scales for each of the three drugs examined correlated significantly, with the strongest relationship being for alcohol and marijuana experiences. Significant associations were identified between how a person experienced a drug and abuse and dependence status for the same or different drug.

CONCLUSION

Cross-drug relationships provide evidence for a common liability or sensitivity towards responding in a similar manner to drugs of abuse within and across different pharmacological classes.

Enhancement of the behavioral effects of endogenous and exogenous cannabinoid agonists by phenylmethyl sulfonyl fluoride

Marijuana's effects in humans are most often reported as intoxicating or therapeutic; yet, some humans report dysphoria or other negative affect. To evaluate whether differences in endocannabinoid levels might account for this variability, the present study examined whether sensitivity to cannabinoids changed when anandamide (AEA) metabolism was inhibited through administration of phenylmethyl sulfonyl fluoride (PMSF) a non-specific irreversible amidase inhibitor. Male Long Evans rats were trained to discriminate 3 mg/kg Δ(9)-tetrahydrocannabinol (THC) versus vehicle in 2-lever drug discrimination procedure. ED(50)s for THC and CP 55,940 were lower when administered with PMSF than alone. PMSF administration also potentiated characteristic cannabimimetic effects of THC in ICR mice. Potentiation of AEA's in vivo effects by PMSF were also observed, primarily as a consequence of PMSF inhibition of the enzyme fatty acid amide hydrolase. Enhancement of the effects of THC and CP 55,940 through this mechanism is unlikely, as these cannabinoids are predominantly metabolized through the P450 system. Mass spectrometry revealed that, in the presence of THC, endogenous AEA levels in the brain decreased and that this decrease was prevented by PMSF, suggesting that increased AEA levels may have acted additively with exogenously administered cannabinoids to increase cannabimimetic effects. These findings may account for the varying affect in response to marijuana in humans or cannabinoids in animals while also suggesting that metabolic inhibitors of AEA may potentiate marijuana's intoxicating effects in humans. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.

The Dutch Cannabis Dependence (CanDep) study on the course of frequent cannabis use and dependence: objectives, methods and sample characteristics

This paper presents an overview of the prospective cohort design of the Dutch Cannabis Dependence (CanDep) study, which investigates (i) the three-year natural course of frequent cannabis use (≥ three days per week in the past 12 months) and cannabis dependence; and (ii) the factors involved in the transition from frequent non-dependent cannabis use to cannabis dependence, and remission from dependence. Besides its scientific relevance, this knowledge may contribute to improve selective and indicated prevention, early detection, treatment and cannabis policies. The secondary objectives are the identification of factors related to treatment seeking and the validation of self report measures of cannabis use. Between September 2008 and April 2009, baseline data were collected from 600 frequent cannabis users with an average age of 22.1 years, predominantly male (79.3%) and an average cannabis use history of 7.1 years; 42.0% fulfilled a (12-month DSM-IV) diagnosis of cannabis dependence. The response rate was 83.7% after the first follow up at 18 months. The second and last follow-up is planned at 36 months. Computer assisted personal interviews (CAPI) were conducted which covered: cannabis use (including detailed assessments of exposure, motives for use and potency preference); use of other substances; DSM-IV internalizing and externalizing mental disorders; treatment seeking; personality; life events; social support and social functioning.

Ethanol-induced effects on the dopamine and serotonin systems in adult Wistar rats are dependent on early-life experiences

Some individuals control their ethanol consumption throughout life, but others escalate their intake to levels that increase the risk for addiction. The early environment influences the individual response to ethanol and affects the underlying physiological processes that lead to a transition from a voluntary to a compulsive use of ethanol. However, the neurobiological substrates for these processes are not understood. The present study aimed to test the hypothesis that early environmental experiences affect the neurobiological effects that are induced by voluntary ethanol consumption. Rat pups were subjected to three different rearing environments: conventional animal facility rearing or separation from dam and littermates for either 15 or 360min. In adulthood, the rats were exposed to a two-bottle free choice between ethanol and water for seven weeks. Tissue levels of dopamine, 5-hydroxytryptamine (5-HT) and their metabolites were measured in brain areas that have been implicated in reward and addiction processes. Differences in ethanol-induced effects were noted in 5-HT-related measurements in the nucleus accumbens and ventral tegmental area and in dopamine-related measurements in the dorsal raphe nucleus (DRN). These results provided evidence of an early environmental impact on interactive neuronal circuits between the DRN and reward pathways. The amygdala, a key area in addiction processes, was particularly sensitive to early-life conditions. The animals that experienced the longest separation differed from the others; they had low basal 5-HT levels and responded with an increase in 5-HT after ethanol. These altered responses to initial ethanol consumption as a result of early environmental factors may affect the transition from habitual to compulsive drinking and contribute to individual vulnerability or resilience to addiction.

Parental alcohol dependence, socioeconomic disadvantage and alcohol and cannabis dependence among young adults in the community

We tested the hypothesis that socioeconomic disadvantage exacerbates the intergenerational transmission of substance dependence. Among 3056 community-based young adults (18-22 years, 2007), the prevalence of alcohol dependence (WHO AUDIT, 5.8%) and cannabis dependence (DSM IV criteria, 7.3%) was doubled in the presence of combined parental alcohol dependence and socioeconomic disadvantage.

Common and drug-specific genetic influences on subjective effects to alcohol, tobacco and marijuana use

AIM

To examine variation in positive and negative subjective effects to alcohol, tobacco and marijuana and covariation between these three drugs and each effect.

DESIGN

Retrospective self-reports of subjective effects were collected to estimate the genetic and environmental influences and the extent of their specificity across three drugs.

PARTICIPANTS

Data were drawn from 1299 adolescent and young adult same- and opposite sex twin- and sibling-pairs participating in the Colorado Center for Antisocial Drug Dependence (CADD).

SETTING

A large, collaborative, longitudinal study of substance use and antisocial behavior in community and clinical adolescents.

MEASUREMENT

  Subjective effects were assessed using a 13-item questionnaire that included positive and negative responses to alcohol, tobacco and marijuana.

FINDINGS

Heritable influences contributed moderately (additive genetic effects 16-56%) to positive and negative subjective effects to all three drugs and did not differ for males and females. Genetic and environmental contributions to positive and negative subjective effects are largely non-overlapping for tobacco and marijuana. Multivariate genetic modeling indicated that subjective effects to alcohol, tobacco and marijuana share a common, heritable etiology and that drug-specific genetic influences were an important contributor to individual differences in drug response.

CONCLUSIONS

  Results from our genetic analyses suggest that subjective effects to these commonly used and misused drugs are heritable and that the genetic and environmental influences on effects to one drug also influence subjective effects to other drugs.

Estrogen receptor 1 gene (ESR1) is associated with restrictive anorexia nervosa

Anorexia nervosa (AN) is a highly heritable young-onset psychiatric illness the etiology of which remains unknown. Estrogen alpha and beta receptors, encoded by ESR1 and ESR2 genes, are involved in food intake regulation and eating behavior, and may have a potential role in AN. We performed a family-based association study of 17 single-nucleotide polymorphisms (SNPs) encompassing ESR1 and ESR2 genes in a cohort of 321 French AN families. We attempted to replicate this finding in a cohort of 41 restrictive AN (RAN) families and in a population-based study of 693 young women. Using the transmission disequilibrium test, a significant over-transmission was detected between AN and ESR1 rs726281 and rs2295193. These SNPs and another among ESR1 were more specifically associated with the RAN subtype (rs726281, p=0.005, odds ratio (OR)=2.1, 95% confidence interval (95% CI)=1.2-3.6; rs3798577, p=0.021, OR=1.6, 95% CI=1.1-2.3; and rs2295193, p=0.007, OR=1.7, 95% CI=1.2-2.5). A large eight-SNPs haplotype of ESR1 gene was also associated with AN (p<0.0001, OR=3.1, 95% CI=1.8-5.1). Association of ESR1 SNPs and RAN was driven by paternal over-transmissions (p<0.0001, OR=3.7, 95% CI=1.9-7.3). Furthermore, we confirmed the preferential paternal over-transmission of the ESR1 rs726281 on the independent German sample of 41 RAN trios (p=0.025, OR=3, 95% CI=1.1-8.3). Finally, rs3798577 was associated with eating disorders in a population-based sample of 693 women (p<0.01). Our findings are strongly in favor of an association between ESR1 polymorphisms and AN. In particular, ESR1 gene confers a high risk of vulnerability to the restrictive subtype of AN, and suggests that the estrogen pathway has to be further analyzed in AN.

Subjective effects to marijuana associated with marijuana use in community and clinical subjects

INTRODUCTION

Marijuana is the most commonly used illicit drug among adolescents. Marijuana use induces both psychological and physiological responses, which can be interpreted by an individual in a variety of ways (i.e. subjective effects). We have examined subjective effects in adolescent, young adult community, and clinical populations to determine how patterns of use may be predicted by an individual's subjective experiences with the drug.

METHOD

Participants were community and clinical sample subjects drawn from the Colorado Center of Antisocial Drug Dependence (CADD) and a sample of adjudicated youth from the Denver metropolitan area (aged 11-30). They were evaluated with the Composite International Diagnostic Interview-Substance Abuse Module (CIDI-SAM) and the Lyons battery for subjective effects. Scales for subjective effects were created using Mokken scale analysis. Multivariate linear and logistic regression was used to examine associations between the subjective scales and marijuana outcomes.

RESULTS

Mokken scaling revealed two subjective effects scales, positive and negative. Both scales were significantly positively associated with marijuana abuse or dependence in both the community and clinical sample and regular use in the community sample. The negative scale was negatively associated with past six-month use in the community sample (p<0.05) and clinical sample, after controlling for age and gender effects.

CONCLUSIONS

These findings suggest that diverse subjective experiences with marijuana can be ordered hierarchically and that the resulting short scales can be used in either clinical or community settings. Further, they suggest that the potential for marijuana use problems is related to the type of subjective experience from marijuana exposure.