Heavy Cannabis Research Articles

Emotional processing deficits in chronic cannabis use: A replication and extension

Heavy cannabis use is associated with interpersonal problems that may arise in part from the inaccurate perception of emotional faces. Only one study reports impairments in emotional facial affect processing in heavy cannabis users; however, it is not clear whether these findings were attributable to differences between cannabis users and controls in schizotypy or gender, rather than from cannabis use itself. A total of 25 frequent cannabis users and 34 non-using controls completed an emotional processing task in an independent groups design. We asked participants to identify the emotions on faces morphed from neutral to 100% intensity, for six basic emotions. We measured percentage hit rate, sensitivity and response bias. Schizotypy was indexed using the Schizotypal Personality Questionnaire. Cannabis users showed lower accuracy and sensitivity on the emotional recognition task. Gender and schizotypy did not differ between the two groups. Men showed lower accuracy on the emotional processing task, but impairments in cannabis users remained when covarying for gender. Schizotypy negatively correlated with sensitivity scores, but this was unreliable when accounting for the groups. Chronic cannabis users showed generalised impairment in emotional processing. These results appeared as independent of the emotional processing deficits amongst men, and were not related to schizotypy.

Cross‐sectional and prospective relation of cannabis potency, dosing and smoking behaviour with cannabis dependence: an ecological study

Increased delta-9-tetrahydrocannabinol (THC) concentrations in cannabis may lead to higher THC exposure, cannabis dependence and treatment need, but users may also adapt the actual intake of THC through reduced inhalation of THC containing smoke (titration). We investigated whether consumers of stronger cannabis use less cannabis per joint or inhale less smoke than those using less potent cannabis and whether these factors predict cannabis dependence severity. Heavy cannabis users (n = 98) brought their own cannabis, rolled a joint and smoked it ad libitum in a naturalistic setting. We analysed the content of the joint, its association with smoking behaviour and the cross-sectional and prospective (1.5-year follow-up) relations between smoking behaviour and cannabis dependence severity (total number of DSM-IV dependence symptoms). THC concentration in cannabis (range 1.10-24.70%) was correlated positively with cannabis dose per joint (b = 0.008, P = 0.01), but the resulting THC concentration per joint (range 0.24-15.72%) was associated negatively with inhalation volume (b = -0.05, P = 0.03). Smoking behaviour measures (number of puffs, inhaled volume, reduction of puff volume and puff duration while smoking) predicted follow-up dependence severity, independently of baseline dependence severity and monthly THC dose (number of joints × cannabis dose × cannabis THC concentration). Monthly THC dose only predicted follow-up dependence severity when unadjusted for baseline severity. Cannabis users titrate their delta-9-tetrahydrocannabinol intake by inhaling lower volumes of smoke when smoking strong joints, but this does not fully compensate for the higher cannabis doses per joint when using strong cannabis. Thus, users of more potent cannabis are generally exposed to more delta-9-tetrahydrocannabinol. Smoking behaviour appears to be a stronger predictor for cannabis dependence severity than monthly delta-9-tetrahydrocannabinol dose.

Investigating Autobiographical Memory Impairments in Chronic Heavy Cannabis Users: Methodology and Hypotheses

Cannabis is the most consumed illicit substance in industrialized countries, and the French count among the highest users in Europe [1]. Chronic heavy cannabis use (CHCU) is usually associated with a deficit of executive functions [2] together with impaired working memory [3], and both these systems are involved in various memory processes, including autobiographical memory (AM) [4]. AM is defined as a set of personal general knowledge and memories of highly specific episodes that an individual accumulates throughout their life. AM is inherent to the construction of self and personal identity, and gives a sense of continuity of the self across time [5]. The model the most widely used to explain AM running is that of Conway and Pleydell-Pearce [6].

Functional connectivity alterations in brain networks relevant to self-awareness in chronic cannabis users

BackgroundRecreational drugs are generally used to intentionally alter conscious experience. Long-lasting cannabis users frequently seek this effect as a means to relieve negative affect states. As with conventional anxiolytic drugs, however, changes in subjective feelings may be associated with memory impairment. We have tested whether the use of cannabis, as a psychoactive compound, is associated with alterations in spontaneous activity in brain networks relevant to self-awareness, and whether such potential changes are related to perceived anxiety and memory performance. MethodsFunctional connectivity was assessed in the Default and Insula networks during resting state using fMRI in 28 heavy cannabis users and 29 control subjects. Imaging assessments were conducted during cannabis use in the unintoxicated state and repeated after one month of controlled abstinence. ResultsCannabis users showed increased functional connectivity in the core of the Default and Insula networks and selective enhancement of functional anticorrelation between both. Reduced functional connectivity was observed in areas overlapping with other brain networks. Observed alterations were associated with behavioral measurements in a direction suggesting anxiety score reduction and interference with memory performance. Alterations were also related to the amount of cannabis used and partially persisted after one month of abstinence. ConclusionsChronic cannabis use was associated with significant effects on the tuning and coupling of brain networks relevant to self-awareness, which in turn are integrated into brain systems supporting the storage of personal experience and motivated behavior. The results suggest potential mechanisms for recreational drugs to interfere with higher-order network interactions generating conscious experience.

Substance use patterns associated with injection drug use initiation in a low-threshold methadone-maintained sample

Substance use patterns associated with the initiation of injection drug use were examined in a sample of low-threshold methadone-maintained injection drug users. Injection initiation tended to coincide with concurrent heavy alcohol and cannabis use, increasing use of stimulants such as cocaine, and the onset of prescription opioid and sedative misuse. Nearly half of the sample reported simultaneously using at least one other drug (excluding tobacco) during the first-ever injection drug use session, with alcohol being the most commonly co-administered substance. Findings suggest that specific patterns of multiple substance use may be appropriate targets for prevention of injection drug use.

Cannabis withdrawal syndrome: An important diagnostic consideration in adolescents presenting with disordered eating

Although previously thought to have no withdrawal symptoms, there is now convergent evidence for a cannabis withdrawal syndrome (CWS), criteria for its diagnosis, and evidence of its impact in the adolescent population. Cannabis withdrawal syndrome represents an important and under-recognized consideration in adolescents with disordered eating. We describe three clinical cases of adolescents presenting to an eating disorders program with primary complaints of gastrointestinal symptoms, food avoidance, and associated weight loss. They did not meet the criteria for an eating disorder, but did fulfill the DSM-5 criteria for CWS. This report emphasizes the importance of considering the impact of heavy cannabis use in adolescents presenting with gastrointestinal complaints, and eating disorder symptoms, including weight loss.

Relationship between working‐memory network function and substance use: a 3‐year longitudinal fMRI study in heavy cannabis users and controls

Deficient executive functions play an important role in the development of addiction. Working-memory may therefore be a powerful predictor of the course of drug use, but chronic substance use may also impair working-memory. The aim of this 3-year longitudinal neuro-imaging study was to investigate the relationship between substance use (e.g. alcohol, cannabis, nicotine, illegal psychotropic drugs) and working-memory network function over time in heavy cannabis users and controls. Forty-nine participants performed an n-back working-memory task at baseline and at 3-year follow-up. At follow-up, there were 22 current heavy cannabis users, 4 abstinent heavy cannabis users and 23 non-cannabis-using controls. Tensor-independent component analysis (Tensor-ICA) was used to investigate individual differences in working-memory network functionality over time. Within the group of cannabis users, cannabis-related problems remained stable, whereas alcohol-related problems, nicotine dependence and illegal psychotropic substance use increased over time. At both measurements, behavioral performance and network functionality during the n-back task did not differ between heavy cannabis users and controls. Although n-back accuracy improved, working-memory network function remained stable over time. Within the group of cannabis users, working-memory network functionality was not associated with substance use. These results suggest that sustained moderate to heavy levels of cannabis, nicotine, alcohol and illegal psychotropic substance use do not change working-memory network functionality. Moreover, baseline network functionality did not predict cannabis use and related problems three years later, warranting longitudinal studies in more chronic or dependent cannabis users.

Cannabis Cue Reactivity and Craving Among Never, Infrequent and Heavy Cannabis Users

Substance cue reactivity is theorized as having a significant role in addiction processes, promoting compulsive patterns of drug-seeking and drug-taking behavior. However, research extending this phenomenon to cannabis has been limited. To that end, the goal of the current work was to examine the relationship between cannabis cue reactivity and craving in a sample of 353 participants varying in self-reported cannabis use. Participants completed a visual oddball task whereby neutral, exercise, and cannabis cue images were presented, and a neutral auditory oddball task while event-related brain potentials (ERPs) were recorded. Consistent with past research, greater cannabis use was associated with greater reactivity to cannabis images, as reflected in the P300 component of the ERP, but not to neutral auditory oddball cues. The latter indicates the specificity of cue reactivity differences as a function of substance-related cues and not generalized cue reactivity. Additionally, cannabis cue reactivity was significantly related to self-reported cannabis craving as well as problems associated with cannabis use. Implications for cannabis use and addiction more generally are discussed.

Risky Cannabis Use is Associated with Alexithymia, Frontal Lobe Dysfunction, and Impulsivity in Young Adult Cannabis Users

Risky or problematic alcohol use by young adults has been found to be associated with factors such as alexithymia, frontal lobe dysfunction, reward sensitivity, and impulsivity. One interpretation is that these factors reflect inherent traits that predispose to risky substance use in general, a notion examined in the present study. Alexithymia, everyday frontal lobe functioning, sensitivity to reward and punishment, and impulsivity were examined in 138 young adult cannabis users who were divided into Low Risk (n = 99) and Risky (n = 39) users according to their Cannabis Use Disorder Identification Test (CUDIT) scores. Risky cannabis use was significantly positively associated with alexithymia, multiple signs of frontal lobe dysfunction in everyday life, and impulsivity. A broader pattern of dysfunction was indicated for risky cannabis use than for risky alcohol use in this sample. Findings are interpreted as likely reflecting not only inherent traits that predispose to risky substance use in general, but also perhaps residual effects of recent heavy cannabis use in the Risky user group. Longitudinal research is needed to disentangle these competing possibilities.

Cannabis et syndromes coronariens aigus avec sus-décalage de ST

Cannabis is the most common substance of drug abuse in the world and has euphoric and hallucinogenic effects. Its cardiovascular effects are well-known. However, there is limited information concerning cannabis-induced acute coronary syndrome and the exact contribution of cannabis smoking to coronary artery disease. We report and discuss a case of ST-Elevation acute coronary syndrome occurring in a young patient aged 24 years, who was a heavy cannabis smoker.

Effect of baseline cannabis use and working‐memory network function on changes in cannabis use in heavy cannabis users: A prospective fMRI study

Theoretical models of addiction suggest that a substance use disorder represents an imbalance between hypersensitive motivational processes and deficient regulatory executive functions. Working-memory (a central executive function) may be a powerful predictor of the course of drug use and drug-related problems. Goal of the current functional magnetic resonance imaging study was to assess the predictive power of working-memory network function for future cannabis use and cannabis-related problem severity in heavy cannabis users. Tensor independent component analysis was used to investigate differences in working-memory network function between 32 heavy cannabis users and 41 nonusing controls during an N-back working-memory task. In addition, associations were examined between working-memory network function and cannabis use and problem severity at baseline and at 6-month follow-up. Behavioral performance and working-memory network function did not significantly differ between heavy cannabis users and controls. However, among heavy cannabis users, individual differences in working-memory network response had an independent effect on change in weekly cannabis use 6 months later (ΔR(2) = 0.11, P = 0.006, f(2) = 0.37) beyond baseline cannabis use (ΔR(2) = 0.41) and a behavioral measure of approach bias (ΔR(2) = 0.18): a stronger network response during the N-back task was related to an increase in weekly cannabis use. These findings imply that heavy cannabis users requiring greater effort to accurately complete an N-back working-memory task have a higher probability of escalating cannabis use. Working-memory network function may be a biomarker for the prediction of course and treatment outcome in cannabis users.

Cannabis dependence, cognitive control and attentional bias for cannabis words

One of the characteristics of people suffering from addictive behaviors is the tendency to be distracted by drug cues. This attentional bias for drug cues is thought to lead to increased craving and drug use, and may draw individuals into a vicious cycle of drug addiction. In the current study we developed a Dutch version of the cannabis Stroop task and measured attentional bias for cannabis words in a group of heavy cannabis users and matched controls. The classical Stroop task was used as a global measure of cognitive control and we examined the relationship between cognitive control, cannabis-related problems, cannabis craving and cannabis attentional bias. Using our version of the cannabis Stroop task, a group of heavy cannabis users showed attentional bias to cannabis words, whereas a control group of non-users did not. Furthermore, within the group of cannabis users, those who were clinically recognized as dependent showed a stronger attentional bias than the heavy, non-dependent users. Cannabis users who displayed reduced cognitive control (as measured with the classical Stroop task) showed increased session-induced craving. Contrary to expectations, however, cognitive control did not appear to modulate the relationship between attentional bias to cannabis words (cannabis Stroop task) and cannabis dependence. This study confirmed the relationship between cannabis dependence and attentional bias and extends this by highlighting a moderating role for cognitive control, which may make some more vulnerable to craving.

The association between cannabis use and depression: a systematic review and meta-analysis of longitudinal studies

Longitudinal studies reporting the association between cannabis use and developing depression provide mixed results. The objective of this study was to establish the extent to which different patterns of use of cannabis are associated with the development of depression using meta-analysis of longitudinal studies. Peer-reviewed publications reporting the risk of developing depression in cannabis users were located using searches of EMBASE, Medline, PsychINFO and ISI Web of Science. Only longitudinal studies that controlled for depression at baseline were included. Data on several study characteristics, including measures of cannabis use, measures of depression and control variables, were extracted. Odds ratios (ORs) were extracted by age and length of follow-up. After screening for 4764 articles, 57 articles were selected for full-text review, of which 14 were included in the quantitative analysis (total number of subjects = 76058). The OR for cannabis users developing depression compared with controls was 1.17 [95% confidence interval (CI) 1.05-1.30]. The OR for heavy cannabis users developing depression was 1.62 (95% CI 1.21-2.16), compared with non-users or light users. Meta-regression revealed no significant differences in effect based on age of subjects and marginal difference in effect based on length of follow-up in the individual studies. There was large heterogeneity in the number and type of control variables in the different studies. Cannabis use, and particularly heavy cannabis use, may be associated with an increased risk for developing depressive disorders. There is need for further longitudinal exploration of the association between cannabis use and developing depression, particularly taking into account cumulative exposure to cannabis and potentially significant confounding factors.

Response inhibition and elevated parietal-cerebellar correlations in chronic adolescent cannabis users

The ability to successfully inhibit an inappropriate behaviour is a crucial component of executive functioning and its impairment has been linked to substance dependence. Cannabis is the most widely used illicit drug in adolescence and, given the accelerated neuromaturation during adolescence, it is important to determine the effects of cannabis use on neurocognitive functioning during this developmental period. In this study, a cohort of adolescent heavy cannabis users and age-matched non-cannabis-using controls completed a Go/No-Go paradigm. Users were impaired in performance on the task but voxelwise and region-of-interest comparisons revealed no activation differences between groups. Instead, an analysis of correlation patterns between task-activated areas revealed heightened correlation scores in the users between bilateral inferior parietal lobules and the left cerebellum. The increased correlation activity between these regions was replicated with resting state fMRI data and was positively correlated with self-reported, recent cannabis usage. The results suggests that the poorer inhibitory control of adolescent cannabis users might be related to aberrant connectivity between nodes of the response inhibition circuit and that this effect is observable in both task-induced and intrinsic correlation patterns.This article is part of the Special Issue Section entitled ‘Neuroimaging in Neuropharmacology’.

Immature brain in adolescence

Immature brain in adolescence

Heavy cannabis use negatively impacts on bone density: a population based prospective study

Searchable abstracts of presentations at key conferences on calcified tissues ISSN 2052-1219 (online)

Cannabis intoxication inhibits avoidance action tendencies: a field study in the Amsterdam coffee shops

Experimental laboratory studies suggest that the approach bias (relatively fast approach responses) toward substance-related materials plays an important role in problematic substance use. How this bias is moderated by intention to use versus recent use remains unknown. Moreover, the relationship between approach bias and other motivational processes (satiation and craving) and executive functioning remains unclear. The aim of this study was to investigate the cannabis approach bias before and after cannabis use in real-life setting (Amsterdam coffee shops) and to assess the relationship between approach bias, craving, satiation, cannabis use, and response inhibition. Cannabis, tobacco, and neutral approach and avoidance action tendencies were measured with the Approach Avoidance Task and compared between 42 heavy cannabis users with the intention to use and 45 heavy cannabis users shortly after cannabis use. The classical Stroop was used to measure response inhibition. Multiple regression analyses were conducted to investigate relationships between approach bias, satiation, craving, cannabis use, and response inhibition. In contrast to the hypotheses, heavy cannabis users with the intention to use did not show a cannabis approach bias, whereas intoxicated cannabis users did show an approach bias regardless of image category. This could be attributed to a general slowing of avoidance action tendencies. Moreover, craving was negatively associated with the approach bias, and no relationships were observed between the cannabis approach bias, satiation, prior cannabis use, and response inhibition. Cannabis intoxication in a real-life setting inhibited general avoidance. Expression of the cannabis approach bias appeared not to be modulated by satiation or response inhibition.

Quasi‐legal cannabis in Colorado and Washington: local and national implications

Quasi‐legal cannabis in <scp>C</scp>olorado and <scp>W</scp>ashington: local and national implications

Influence of Ethanol on the Pharmacokinetic Properties of 9-Tetrahydrocannabinol in Oral Fluid

Oral fluid (OF) tests aid in identifying drivers under the influence of drugs. In this study, 17 heavy cannabis users consumed alcohol to achieve steady blood alcohol concentrations of 0 to 0.7 g/L and smoked cannabis 3 h afterward. OF samples were obtained before and up to 4 h after smoking and on-site tests were performed (Dräger DrugTest 5000 and Securetec DrugWipe 5+). Maximum concentrations of tetrahydrocannabinol (THC) immediately after smoking (up to 44,412 ng/g) were below 4,300 (median 377) ng/g 1 h after smoking and less than 312 (median 88) ng/g 3 h later with 5 of 49 samples negative, suggesting that recent cannabis use might occasionally not be detectable. An influence of alcohol was not observed. Drinking 300 mL variably influenced THC concentrations (median only -29.6%), which suggests that drinking does not markedly affect on-site test performance. Many (92%) Dräger tests performed 4 h after smoking were still positive, indicating sufficient sensitivity for recent cannabis use. Differences in the results of a roadside study with DrugTest 5000 (sensitivity 84.8%, specificity 96.0%, accuracy 84.3%) could be explained by a higher number of true negatives, differences between OF and serum and differences between occasional and chronic users.

Cannabis and psychosis: what causes what?

Converging lines of evidence suggest that cannabinoids can produce a full range of transient schizophrenia-like positive, negative and cognitive symptoms. Cannabinoids also produce some psychophysiological deficits also known to be present in schizophrenia. It is also clear that, in individuals with an established psychotic disorder, cannabinoids can exacerbate symptoms, trigger relapse, and have negative consequences on the course of the illness. Increasing evidence suggests that early and heavy cannabis exposure may increase the risk of developing a psychotic disorder such as schizophrenia. The relationship between cannabis exposure and schizophrenia fulfills some, but not all, of the usual criteria for causality. However, most people who use cannabis do not develop schizophrenia, and many people diagnosed with schizophrenia have never used cannabis. Therefore, it is likely that cannabis exposure is a “component cause” that interacts with other factors to “cause” schizophrenia or other psychotic disorders, but is neither necessary nor sufficient to do so alone. Further work is necessary to identify the factors that underlie individual vulnerability to cannabinoid-related psychosis and to elucidate the biological mechanisms underlying this risk.