A review of the literature on marijuana and interpersonal violence

Marijuana use and interpersonal violence are major public health problems. The present review examines the available empirical and theoretical literature on the relationship between marijuana and violence, including past theoretical models, the link between marijuana use and interpersonal violence (including intimate partner violence), and the relationship between marijuana withdrawal and violence. While results from laboratory-based studies are inconclusive, results of cross-sectional and longitudinal research provide support for an association between marijuana use/withdrawal and various types of violence. Given the lack of empirical support for existing models, a new biopsychosocial model of the marijuana–violence relationship is proposed. Examining methods to test this model and application of current findings to treatment are discussed.     

A preliminary investigation of acceptance and commitment therapy as a treatment for marijuana dependence in adults

In this investigation, 3 adults who met criteria for marijuana dependence were treated using an abbreviated version of acceptance and commitment therapy (ACT). The treatment was delivered in eight weekly 90-min individual sessions. The effects of the intervention were assessed using a nonconcurrent multiple baseline across participants design. Self-reported marijuana use, confirmed through oral swabs, reached zero levels for all participants at posttreatment. At a 3-month follow-up, 1 participant was still abstinent and the other 2 were using but at a lower average level of consumption compared to baseline. Depression, anxiety, withdrawal symptoms, and general levels of experiential avoidance generally improved. This preliminary test suggests that additional development and testing of ACT for marijuana use are warranted.     

Sex Differences in Response to Marijuana in a Social Setting

Due to the failure to include women in the subject samples of most experimental investigations of the effects of cannabis, the possibility exists that the data obtained on this social intoxicant are applicable to only 49% of the population. Those few studies that have compared males and females have focused on performance variables and have demonstrated very few differences. It was hypothesized that the most likely area for male/female marijuana differences would be that of social interactions and behaviors related to these interactions.
In a relaxed, informal atmosphere, Es videotaped the social interactions of groups of female friends, female strangers, male friends, or male strangers as they smoked coltsfoot, placebo, and marijuana. In addition to social-condition and drug-condition differences, we obtained statistically significant effects indicating that the women responded both to the social situations and to the drug differently from the men. In general, the women interacted with each other more positively than did the men. These effects were paralleled by sex differences in mood, person perception, and even in how pleasurable or annoying the experimental tasks were.
These data are of import not only in the area of cannabis research but in the field of social interactions and the study of female/male differences as well.     

Are the symptoms of cannabis use disorder best accounted for by dimensional, categorical, or factor mixture models? A comparison of male and female young adults

Despite the consensus that criteria for cannabis abuse and dependence and symptoms of withdrawal are best explained by a single latent liability, it remains unknown whether alternative models provide a better explanation of these criteria. A series of latent factor, latent class, and hybrid factor mixture models were fitted to data from 872 recent cannabis users from the Minnesota Twin Family Study who completed Diagnostic and Statistical Manual of Mental Disorders (3rd ed., revised, and 4th ed.) diagnostic criteria for cannabis abuse, dependence, and symptoms of withdrawal. Despite theoretical appeal, results did not support latent class or factor mixture modeling. Instead, symptoms of abuse, dependence, and withdrawal were better summarized by a single latent factor Cannabis Use Disorder (CUD) for male and female young adults. An almost 2-fold sex difference in item endorsement was best explained by a single mean difference on the CUD factor, indicating that young men have a greater latent liability toward expressing CUD.     

Effects of delta 9-THC on marijuana smoking, dose choice, and verbal report of drug liking.

The effects of delta 9-tetrahydrocannabinol content of marijuana on cigarette smoking, dose choice, and verbal report of drug "liking" by adult males living in a residential laboratory were investigated. Marijuana cigarettes were available during programmed intervals while subjects were engaged in recreational activities. The tetrahydrocannabinol content of the cigarettes remained constant each day, but was changed across days. Subjects provided written ratings of drug liking at the end of each day. In the first study, placebo or active (2.3% delta 9-tetrahydrocannabinol) marijuana cigarettes were available for 1-, 2-, or 3-day intervals at varying times of day. The number of cigarettes smoked was unrelated to tetrahydrocannabinol content, although verbal reports of drug liking were consistently higher when marijuana cigarettes containing tetrahydrocannabinol were smoked. In a second study, a choice procedure, consisting of four 3-day blocks of 2 sample days and 1 choice day, was used. On sampling days, subjects smoked cigarettes varying in tetrahydrocannabinol content (0.0, 2.0, and 3.5%, w/w); on choice days they were allowed to choose between the two previously sampled doses. The number of cigarettes was not consistently related to tetrahydrocannabinol content. Ratings of drug liking were increased when marijuana cigarettes contained tetrahydrocannabinol, but ratings of marijuana containing 2.0% and 3.5% of the compound were similar. In contrast, subjects consistently chose the 3.5% dose over either the 0.0% or 2.0% dose. Dose choice was more sensitive to tetrahydrocannabinol content than either reports of drug liking or numbers of cigarettes smoked.     

A scoping review of predictors of driving under the influence of cannabis (DUIC) in young drivers

BackgroundRecreational and medical legalization of cannabis or marijuana use in countries and states continues to increase. Young adults aged 16–24 years have the highest prevalence rates of cannabis use. Young driver cannabis use is an incompletely understood traffic safety issue.ObjectivesThe purposes of this scoping review were to characterize the predictors of driving under the influence of cannabis (DUIC) among healthy young drivers and to identify research gaps.Inclusion criteriaA self-reported measure of DUIC and a correlation (r, odds ratio, risk ratio) to demographic or behavioral variables such as age, gender and frequency of use was required for inclusionSources of evidenceAPA PsycInfo, SPORTDiscus, Academic Search Complete, Google Scholar, MEDLINE Complete, Scopus, Embase, ERIC, TRID and POPLINE databases were searched using an a priori protocol.MethodsThe PRISMA-ScR methods and checklist were used to conduct the scoping review. After the removal of duplicates, abstract screening (N = 999), and full-text review (N = 173), 19 primary studies met inclusion criteria. Predictors were coded and mapped into four primary thematic categories: social, individual, driving and substance use.ResultsOf the included studies, a total of 52,197 respondents were surveyed in-person or online and 51.8 percent were males. The predominant predictors of DUIC included being a male, high school senior, with lower grades, having a younger ‘age of first cannabis use’, a higher frequency of consumption, a reduced perception of danger, repeatedly binge drinking, a history of driving under the influence of alcohol and living with fewer parents.Research gapsIdentified research gaps include methods used to study young drivers, cannabis edibles, chronic user tolerance, driver adaptation, passengers of drivers who consumed cannabis, combined use with other legal and illicit drugs, and combined smartphone and cannabis use.ConclusionThe results of this scoping review can be used to develop and target general and specific predictors of DUIC in novice, teen and young drivers. Additional research designs will be required to gain a more complete evidence-based understanding of the effects of cannabis on young drivers.     

Examining a structural model of the relationships among alcohol use,marijuana/hashish use,their effects,and emotional and psychological problems over time in a cohort of high‐risk youths

Using data collected in a longitudinal study of detained juveniles, we test a model of the relationships among alcohol and marijuana or hashish use, reported adverse effects of the use of these substances, and emotional and psychological problems. Significant interrelationships were found among these factors over time. Degree of involvement in alcohol and marijuana or hashish use (measured either by self‐reports or both self‐reports and urine test results) was significantly related at Time 1 with the number of reported averse effects of the use of each specific substance; a similar relationship was found at Time 2 for marijuana or hashish use. In addition, emotional and psychological problems were significantly associated with reported adverse effects of the use of alcohol or marijuana or hashish at each time period. The results further indicate that youths who become more involved in the use of alcohol or marijuana or hashish over time report more adverse effects of their use of each of these substances. These findings highlight a network of interconnected experiences that add insight into the youths’ functioning over time. At the same time, the youths’ Time 2 emotional and psychological problems, reported effects of their alcohol use, and reported effects of their marijuana or hashish use are weakly predicted by the variables in the model; these findings suggest considerable change in these experiences over time. Theoretical and policy implications of these findings are discussed.     

Life Satisfaction and Cannabis Use: A Study on Young Adults

Cannabis is the illicit substance most used by young adults and adolescents in rich nations. Cannabis use may have negative consequences on mental and physical health and has been associated with low wellbeing indexes (i.e., life satisfaction). The present study aims to investigate the relationship of life satisfaction with cannabis use in young adults compared with personality and sociodemographic variables. Previous studies have found relationships between the Big Five traits and cannabis use as well as a gender gap. Males have been shown to have a higher consumption of cannabis than females. We conducted a survey by means of a self-report questionnaire on a sample of 600 young adults (average age 22.20 years) and performed a regression analysis to test the relationships of sociodemographic variables, personality, and life satisfaction with cannabis use. The results confirmed the gender gap and showed an association between cannabis use and conscientiousness, agreeableness, openness and life satisfaction. Life satisfaction was negatively related to cannabis use, which suggests that this behaviour may be motivated by coping with unsatisfactory life conditions.     

Weighing the Evidence: A Systematic Review on Long-Term Neurocognitive Effects of Cannabis Use in Abstinent Adolescents and Adults

Findings on neurocognitive effects of sustained cannabis use are heterogeneous. Previous work has rarely taken time of abstinence into account. In this review, we focus on understanding sustained effects of cannabis, which begin when clinical symptoms of the drug have worn off after at least 14 days. We conducted a search between 2004 and 2015 and found 38 studies with such a prolonged abstinence phase. Study-design quality in terms of evidence-based medicine is similar among studies. Studies found some attention or concentration deficits in cannabis users (CU). There is evidence that chronic CU might experience sustained deficits in memory function. Findings are mixed regarding impairments in inhibition, impulsivity and decision making for CU, but there is a trend towards worse performance. Three out of four studies found evidence that motor function remains impaired even after a time of abstinence, while no impairments in visual spatial functioning can be concluded. Functional imaging demonstrates clear differences in activation patterns between CU and controls especially in hippocampal, prefrontal and cerebellar areas. Structural differences are found in cortical areas, especially the orbitofrontal region and the hippocampus. Twenty studies (57 %) reported data on outcome effects, leading to an overall effect size of r _mean?=?.378 (CI 95 %?=?[.342; .453]). Heavy use is found to be more consistently associated with effects in diverse domains than early age of onset. Questions of causality―in view of scarce longitudinal studies, especially those targeting co-occurring psychiatric disorders―are discussed.     

Adult social behavioral effects of heavy adolescent marijuana use among African Americans

The authors examined the effects of heavy adolescent marijuana use on employment, marriage, and family formation and tested both dropping out of high school and adult marijuana use as potential mediators of these associations among a community sample of African Americans followed longitudinally from age 6 to age 32-33. They used propensity score matching to reduce selection bias when estimating the effects of heavy adolescent marijuana use. Logistic regression results on the sample matched on sex, and early demographic and behavioral variables showed that adolescent marijuana use has adult social behavioral consequences: Use of marijuana 20 times or more during adolescence was associated with being unemployed and unmarried in young adulthood and having children outside of marriage for both males and females. Dropping out of high school and more frequent adult marijuana use seem to be important parts of the pathway from adolescent marijuana use to negative life outcomes.     

A controlled trial of an internet-based intervention program for cannabis users

In the last decade, several programs for the treatment of cannabis-related disorders were developed. Until now, no information is available on the efficacy of Internet-based counseling approaches for this target group. This article describes the evaluation of "quit the shit," a web-based intervention developed to help young people to quit or reduce their cannabis use significantly. Cannabis users seeking web-based treatment were included in a two-arm controlled trial conducted on a website for drug-related information and prevention. After the baseline assessment, members of the treatment condition were randomized to a 50-day intervention program. Other trial participants were put on a waiting list. A post-test was conducted 3 months after randomization. Of all 1,292 subjects included in the trial, a total of 206 participants took part at the post-test. Per-protocol- and intention-to-treat analyses were conducted. Members of the treatment condition showed a significantly stronger reduction in cannabis use (primary outcome) than the control group. In the per-protocol analyses, moderate-to-strong effects were found for the reduction of the frequency and the reduction of the quantity of consumed cannabis. Small-to-moderate effects were observed on the secondary outcomes (use-related self-efficacy, anxiety, depression, and life satisfaction). Despite limitations concerning the interpretation of the results, the intervention seems to offer an effective treatment option for persons with cannabis-related problems.     

Associations of substance use problems with intimate partner violence for at-risk men in long-term relationships

Associations of substance use problems in men--defined as a man's meeting at least 1 criterion of dependence on each of a number of substances by his mid-20s--with their perpetration of intimate partner violence (IPV) were examined in an at-risk community sample of 150 men in long-term relationships from their late adolescence to their late 20s. Men who had a problem with substances other than sedatives (especially cannabis and hallucinogens) committed more IPV than did men without such problems. Most of the men who had a problem with marijuana also had an alcohol problem, which explains why alcohol was found to have only an indirect association with IPV. The failure of previous alcohol-use studies to control for co-occurrence of alcohol and marijuana problems may explain the discrepancy with conclusions from past research that alcohol problems contribute directly to the perpetration of IPV.     

Religious Involvement and Dynamics of Marijuana Use: Initiation,Persistence, and Desistence

Studies that examine the effects of adolescent religiosity on the initiation of, persistence in, and desistence from delinquency are rare. Yet, religion may differentially affect dimensions of delinquency in the early life course. Therefore, using data from the National Longitudinal Study of Adolescent Health (Add Health), we examine the relationship between measures of adolescent religion, as well as changes in religious involvement, and later patterns of marijuana use. We also examine the extent to which religious effects, if any, are mediated by key predictors of delinquency drawn from prominent criminological theories. The results suggest that the primary effect of religion on marijuana use is to prevent its initiation in the first place. Only part of religion's preventative effect on initiation is mediated by social bonds, delinquent peers, or self control. Although religious youth are less likely to ever use marijuana, adolescent religious involvement does not significantly predict desistence from marijuana use.     

Investigating the interaction between schizotypy, divergent thinking and cannabis use

Cannabis acutely increases schizotypy and chronic use is associated with elevated rates of psychosis. Creative individuals have higher levels of schizotypy, however links between cannabis use, schizotypy and creativity have not been investigated. We investigated the effects of cannabis smoked naturalistically on schizotypy and divergent thinking, a measure of creativity. One hundred and sixty cannabis users were tested on 1 day when sober and another day when intoxicated with cannabis. State and trait measures of both schizotypy and creativity were administered. Quartile splits compared those lowest (n=47) and highest (n=43) in trait creativity. Cannabis increased verbal fluency in low creatives to the same level as that of high creatives. Cannabis increased state psychosis-like symptoms in both groups and the high creativity group were significantly higher in trait schizotypy, but this does not appear to be linked to the verbal fluency change. Acute cannabis use increases divergent thinking as indexed by verbal fluency in low creatives.     

Reciprocal relations between adolescent substance use and delinquency: a longitudinal latent variable analysis

Reciprocal relations between self-reported substance use and delinquency were examined through the analysis of 4-wave panel data collected from 1,218 high school students. A longitudinal, latent-variable framework was used to investigate interrelationships between changing patterns of generalized involvement in these 2 problem behaviors, while simultaneously accounting for specificity in drug use (e.g., marijuana use) and delinquency (e.g., theft). Analyses revealed that a model of bidirectional effects between polysubstance use and general delinquency was plausible for boys but not for girls. For boys, the effect of delinquency on substance use was small but consistent over time, whereas the effect of substance use on delinquency was larger but restricted to the earlier waves of the study. Implications for the question of whether or not substance use and delinquency have causal connections are discussed.     

Religiosity and adolescent marijuana use

Among adolescents, religiosity has been associated with lower rates of marijuana use, though few studies have examined its impact on the perceived risk of use. There is strong support that perceived risk of using marijuana is negatively correlated with the frequency of use. We examined the relationship among religiosity, perceived risk, and marijuana use from a national survey of adolescents that contained questions about lifetime, weekly, and past month substance use, social support, religious involvement and attitudes, and perceived riskiness of use. We tested a structural equation model of relationships among latent variables of religiosity and perceived risk, and an observed variable of total days of marijuana use in the past 12 months. Results indicated the model was a good fit to the data and described a mediating relationship of perceived risk of use between religiosity and marijuana use. Implications for leveraging religiosity in prevention of substance use are discussed.     

Incremental Validity of Coping-oriented Marijuana Use Motives in the Prediction of Affect-based Psychological Vulnerability

The present investigation examined whether coping-oriented motives to use marijuana, as measured by the Marijuana Motives Measure (MMM; Simons et al. in J. Couns. Psychol. 45:265–273, 1998), were uniquely related to affect-based psychological vulnerability factors among marijuana users. Participants were 131 adult current marijuana users (72 women, M _age = 20.14, SD = 3.37 years). As hypothesized, after controlling for gender, cigarettes smoked per day, past 30-day marijuana use, total years of marijuana use, and alcohol consumption, coping motives were significantly and incrementally related to negative affect-based psychological vulnerability factors. No other marijuana use motives demonstrated a similar type of relationship to the dependent variables, providing a high degree of explanatory specificity. These data suggest that coping-oriented motives to use marijuana may be an important explanatory construct in better understanding marijuana and psychological vulnerability relations.     

Internalizing and Externalizing Problem Behavior: a Test of a Latent Variable Interaction Predicting a Two-Part Growth Model of Adolescent Substance Use

Externalizing symptoms robustly predict adolescent substance use (SU); however, findings regarding internalizing symptoms have been mixed, suggesting that there may be important moderators of the relationship between internalizing problems and SU. The present study used a longitudinal community sample (N?=?387, 55% female, 83% White) to test whether externalizing symptoms moderated the relationship between internalizing symptoms and trajectories of alcohol and marijuana use from early (age 11–12 years old) to late (age 18–19 years old) adolescence. Two-part latent growth models were used to distinguish trajectories of probability of use from trajectories of amount of use among users. Results suggested that externalizing symptoms moderated the association between internalizing symptoms and probability of alcohol, but not marijuana use. The highest probability of alcohol use was observed at high levels of externalizing symptoms and low levels of internalizing symptoms. A negative protective effect of internalizing symptoms on probability of alcohol use was strongest in early adolescence for youth high on externalizing symptoms. Although moderation was not supported for amount of use among users, both domains of symptomology were associated with amount of alcohol and marijuana use as first-order effects. High levels of externalizing symptoms and low levels of internalizing symptoms were associated with high levels of amount of use among users. These findings suggest that developmental models of substance use that incorporate internalizing symptomology should consider the context of externalizing problems and distinguish probability and amount of use.     

Moderating effects of sensitivity to punishment and sensitivity to reward on associations between marijuana effect expectancies and use.

The study examined associations between sensitivity to reward (SR), sensitivity to punishment (SP), positive and negative expectancies, and marijuana use in a college sample (N = 809). Marijuana users (n = 227) reported lower SP and greater SR than nonusers. SR attenuated the association between SP and the probability of marijuana use. SP attenuated the association between positive expectancies and the probability of marijuana use as well as the frequency of use among users. SP potentiated the association between negative expectancies and use. The results indicate that SP and SR have interactive effects and that SP moderates the strength of positive and negative cues for risk behavior.     

Sociodemographic factors,religiosity, academic performance,and substance use among first-year university students in South Africa

The purpose of this study was to identify the relationships among sociodemographic variables, family background, religiosity, course of study, academic performance, and substance use. The sample included 799 first-year students in the age range of 16 to 49 years (M age 20.1 yr., SD = 3.2) chosen at random from the University of the North in South Africa. A Model Core Questionnaire from the WHO on Substance use was administered. Analysis indicated that women smoked tobacco or cannabis and drank less than men, while women took more stimulants and other opiate type drugs than men. Low scores on religiosity was a predictor for past-month tobacco use alcohol use, binge drinking, cannabis use, and having a drinking or drug problem now. Being a member of a Protestant denominational church or a Roman Catholic was a predictor for past-month tobacco and alcohol use. A family history of drinking or drug problems and being a social science or humanities student were predictive for a current alcohol or drug problem. Economic status, education of parents. living arrangement. and rural-urban differences were not associated with substance use. Findings have implications for prevention programmes.