Quantifying cannabis use with the Timeline Followback approach: A psychometric evaluation

Background

In the absence of a standardized cannabis unit, self-report instruments are inadequate for accurate quantification of cannabis use. The study extends the feasibility of using a cannabis substitute to reliably and validly measure quantity of cannabis use.

Method

Ninety-eight adult Australian cannabis users (M age = 27.98, SD = 11.10; 65.31% male) completed a 90-day Timeline Followback interview regarding their cannabis use, utilizing the cannabis substitute Marijuanilla to report on quantity of use. Ninety-two of these individuals completed the interview at two time-points, and 56 of these participants had collaterals corroborate their cannabis use reports.

Results

Inter-rater reliability was excellent, while test–retest reliability was good to excellent. Intra-class correlation coefficients between participant and collateral reports, while similar to previous research, were unacceptable. Quantity of cannabis use statistically significantly added to frequency of use in predicting cannabis problems and dependence severity. Concurrent and discriminant validity were established with single-item and positive impression management measures, respectively. In addition, Marijuanilla appeared similar to one specimen of street seized cannabis, but not to two others. Importantly, participants’ cravings to use cannabis did not increase as a result of using the cannabis substitute to report on their cannabis use.

Conclusions

These data suggest that utilizing Marijuanilla to facilitate the reporting of grams of cannabis use may be reliable and valid; however, such comprehensive assessment may only be necessary for clinical trials and epidemiological studies, which rely on precise estimates of cannabis use.     

Cannabis and depression: An integrative data analysis of four Australasian cohorts

Background

This study presents an integrative data analysis of the association between frequency of cannabis use and severity of depressive symptoms using data from four Australasian cohort studies. The integrated data comprised observations on over 6900 individuals studied on up to seven occasions between adolescence and mature adulthood.

Methods

Repeated measures data on frequency of cannabis use (not used/<monthly/≥monthly/≥weekly) and concurrently assessed depression scores were pooled over the four cohorts. Regression models were fitted to estimate the strength of association between cannabis use and depression. Fixed effects regression methods were used to control for confounding by non-observed fixed factors.

Results

Increasing frequency of cannabis use was associated with increasing depressive symptoms (p < 0.001). In the pooled data weekly users of cannabis had depression scores that were 0.32 (95%CI 0.27–0.37) SD higher than non-users. The association was reduced but remained significant (p < 0.001) upon adjustment for confounding. After adjustment depression scores for weekly users were 0.24 (95%CI 0.18–0.30) SD higher than non-users. The adjusted associations were similar across cohorts. There was a weak age × cannabis use interaction (p < 0.05) suggesting that the association was strongest in adolescence. Attempts to further test the direction of causality using SEM methods proved equivocal.

Conclusions

More frequent cannabis use was associated with modest increases in rates of depressive symptoms. This association was stronger in adolescence and declined thereafter. However, it was not possible from the available data to draw a definitive conclusion as to the likely direction of causality between cannabis use and depression.     

Predicting the transition from frequent cannabis use to cannabis dependence: A three-year prospective study

Background

Frequent cannabis users are at high risk of dependence, still most (near) daily users are not dependent. It is unknown why some frequent users develop dependence, whereas others do not. This study aims to identify predictors of first-incidence DSM-IV cannabis dependence in frequent cannabis users.

Methods

A prospective cohort of frequent cannabis users (aged 18–30, n = 600) with baseline and two follow-up assessments (18 and 36 months) was used. Only participants without lifetime diagnosis of DSM-IV cannabis dependence at baseline (n = 269) were selected. Incidence of DSM-IV cannabis dependence was established using the Composite International Diagnostic Interview version 3.0. Variables assessed as potential predictors of the development of cannabis dependence included sociodemographic factors, cannabis use variables (e.g., motives, consumption habits, cannabis exposure), vulnerability factors (e.g., childhood adversity, family history of mental disorders or substance use problems, personality, mental disorders), and stress factors (e.g., life events, social support).

Results

Three-year cumulative incidence of cannabis dependence was 37.2% (95% CI = 30.7–43.8%). Independent predictors of the first incidence of cannabis dependence included: living alone, coping motives for cannabis use, number and type of recent negative life events (major financial problems), and number and type of cannabis use disorder symptoms (impaired control over use). Cannabis exposure variables and stable vulnerability factors did not independently predict first incidence of cannabis dependence.

Conclusions

In a high risk population of young adult frequent cannabis users, current problems are more important predictors of first incidence cannabis dependence than the level and type of cannabis exposure and stable vulnerability factors.     

“Youthful epidemic” or diagnostic bias? Differential item functioning of DSM-IV cannabis use criteria in an Australian general population survey

Background

Prevalence rates of cannabis abuse and dependence are higher for younger adults when compared with older adults. It is necessary to examine the performance of criteria across age groups to establish whether these differences in prevalence rates are a result of diagnostic bias. The current study aims to investigate whether there is any age-related differential item functioning in the DSM-IV diagnostic criteria for cannabis use disorders using an item response theory approach.

Method

The sample consisted of 10,641 participants in a population-based survey of Australian adults aged 18 years and older. DSM-IV cannabis use disorders were assessed in all respondents who had used cannabis more than five times in the previous twelve months (n = 722). Age-based differential item functioning was assessed in each of the DSM-IV criteria for cannabis use disorders.

Results

Age-based differential item functioning was only detected in the Hazard criterion of the DSM-IV cannabis use disorders. The Hazard criterion was found to be more discriminating for those aged 18–24 when compared with those aged 25 and over.

Conclusions

The DSM-IV criteria for cannabis use disorders appear to function similarly across age groups. Differential item functioning was only detected in the α parameter for the Hazard criterion. These results are discussed with regard to implications for future editions of the DSM system.     

Implicit alcohol cognitions in risky drinking nicotine users with and without co-morbid major depressive disorder

Objective

Alcohol consumption, nicotine use, and major depressive disorder (MDD) are highly co-morbid. The negative reinforcement model of addiction would suggest that smokers may consume alcohol to relieve negative affective symptoms, such as those associated with MDD and withdrawal from nicotine. Over time, these behaviors may become so strongly paired together that they automatically activate a desire to use alcohol, even in the absence of conscious or deliberate intention. This study examined implicit alcohol cognitions in 146 risky drinking nicotine users (n = 83) and non-users (n = 63), to help uncover cognitive mechanisms that link drinking, nicotine use, and depression together. We proposed that nicotine users with a history of MDD would have stronger implicit motivations to drink than non-nicotine users without MDD.

Method

Participants were assessed on lifetime MDD (n = 84) or no MDD (n = 62), and then completed an Implicit Association Task designed to test the strength of associations between alcohol pictures and “approach” words.

Results

Regression analyses showed that implicit alcohol–approach attitudes were stronger among risky drinking nicotine users than non-users. Alcohol–approach motivations were also stronger among risky drinking nicotine users compared to non-users with a history of MDD; nicotine use was unrelated to implicit alcohol cognitions for risky drinkers without MDD.

Conclusions

Implicit cognitive processes may be targeted in behavioral and pharmacological treatments in risky drinking nicotine users, particularly those with depression comorbidity.     

Factors associated with variability and stability of cannabis use in young adulthood

Background

This study investigated the factors associated with initiating cannabis use, reverting to cannabis use and remaining a cannabis user in young adulthood. This is an important area of research as the risk for cannabis initiation is extending beyond adolescence and opportunities to influence cannabis use pathways can emerge throughout the life-course.

Methods

A large, community-based sample was followed prospectively. Data from two successive waves (mean age 23 years and 27 years respectively) of the Path Through Life Study (PATH) were analysed (n = 2045). The longitudinal design enabled change in cannabis use in young adulthood to be predicted based on factors assessed approximately four years prior.

Results

An environment of licit drug use was strongly associated with initiating cannabis use (tobacco: OR = 4.98, 95%CI: 2.31–10.76) and reverting to cannabis use in young adulthood (alcohol: OR = 2.13, 95%CI: 1.42–3.19). Greater fun seeking was found to orientate people towards initiating cannabis use in young adulthood (OR = 1.17, 95%CI: 1.04–1.30). Higher psychoticism increased the odds of remaining a cannabis user (OR = 1.19, 95%CI: 1.07–1.33). Religious involvement was protective of cannabis initiation (OR = 0.89, 95%CI: 0.83–0.95). Early childhood factors did not influence the pattern of cannabis use in young adulthood.

Conclusions

The findings make an important contribution to the development of prevention and intervention strategies for young adults by drawing attention to specific areas of risk and protection.     

Types of polydrug use among Spanish adolescents

Objective

This study examined the types of polydrug use among Spanish adolescents.

Method

1501 high school students (50.6% female) aged 12 to 17 years old (mean age = 14.03, SD = 1.28), from public schools in the city of Girona (Catalonia, Spain), completed the survey.

Results

In the previous six months 20.9% of the Spanish adolescents used alcohol, 18.8% tobacco, 10.5% cannabis and 0.7% cocaine. Specifically, 28.6% of the sample (n = 429; 29% males and 28.2% females) used at least one drug and 13.9% reported polydrug use (n = 208; 12.6% males and 15.1% females). The present research also found that the most critical ages for starting polydrug use were 14 and 15 years old. More than one quarter (27.9%) of the adolescent polydrug users were type A (tobacco and alcohol), 67.8% were type B (cannabis together with tobacco and/or alcohol) and 3.4% were type C (cannabis together with tobacco and/or alcohol, and cocaine).

Conclusions

These results suggest that Spanish adolescents, particularly males, commence polydrug use at an earlier age than other European adolescents. Early preventative strategies and a multisubstance perspective are greatly needed in Spain to avoid the initiation of polydrug use or to prevent progress onto heavier drugs.     

Is the relationship between early-onset cannabis use and educational attainment causal or due to common liability?

Background

Several studies have shown that early cannabis use is correlated with poor educational performance including high school drop-out. The predominant explanation for this relationship is that cannabis use causes disengagement from education. Another explanation is that the association between early cannabis use and educational attainment is not causal, but the result of overlapping risk factors that increase the likelihood of both early cannabis use and disengagement from education. These confounding factors could be of genetic and/or environmental origin.

Methods

Here we use data from a large community-based sample of adult twins (N = 3337) who completed a comprehensive semi-structured telephone interview. We first apply the classical twin-design to determine whether genetic and/or environmental influences underlie the relationship between early-onset cannabis use (prior to age 18) and early school leaving. Next, with a co-twin control design we investigate whether the relationship between the two variables is more likely due to direct causality or overlapping risk factors.

Results

We find a significant phenotypic correlation between early-onset cannabis use and early school leaving (r = 0.26), which could be explained by familial influences (of genetic and/or shared environmental origin). The pattern of odds ratios found in the co-twin control design is not consistent with direct causation, but rather suggests that the association is due to shared environmental factors influencing both variables.

Conclusion

Our findings suggest that the relationship between early-onset cannabis use and school leaving is due to shared environmental risk factors influencing both the risk of early-onset cannabis use and early school leaving.     

Associations between coping,affect, and social support among low-income African American smokers

Objective

Previous research has documented disparities in smoking cessation between African Americans and Caucasians. Many low-income African American smokers face a range of circumstances that may inhibit effective coping during quit attempts, yet previous research has not considered factors that influence coping in this population. This study examined (a) affect (positive and negative) and (b) perceived social support in association with coping strategies.

Methods

The baseline assessment of African American smokers (N = 168) enrolled in a randomized controlled trial included the Positive and Negative Affect Schedule, the Multidimensional Scale of Perceived Social Support, and the Brief COPE. A factor analysis of the Brief COPE resulted in two factors, adaptive and maladaptive strategies.

Results

Participants were mostly single (64%), women (61%), with ≥ 12 years of education (68%), and low-income. They were middle aged (M = 46.1, SD = 8.7), smoked 21.8 (SD = 13.3) cigarettes/day for 24.3 (SD = 11) years, and were moderately nicotine dependent. Results demonstrated that adaptive coping was positively correlated with positive affect and social support. Maladaptive coping was positively correlated with negative affect, and inversely related to positive affect and social support. Multivariate analyses revealed that positive affect and social support were independently associated with adaptive coping strategies. In contrast, maladaptive coping was independently associated with negative affect, but not social support.

Conclusions

Interventions that harness positive resources, such as social support and positive mood, may facilitate adaptive coping. Also, addressing negative affect among low-income African American smokers may be important to reduce maladaptive coping strategies.     

The role of cannabis use within a dimensional approach to cannabis use disorders

Context

Cannabis consumption is central to diagnosis of cannabis use disorders; yet, most research on cannabis disorders has focused just on diagnosis or criteria. The present study examines the ability of a frequency and quantity measure of cannabis use as well as cannabis abuse and dependence criteria to discriminate between individuals across the cannabis use disorder continuum.

Method

A representative sample of USA adults in 2001–2002 (N = 43,093) were queried about the past year frequency of cannabis use and each Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition (DSM-IV) cannabis abuse and dependence criterion. Factor analysis and item response theory (IRT) models were used to define the relationship between observed responses and the underlying unobserved latent trait (cannabis use disorder severity) among past year cannabis users (n = 1603).

Results

Factor analyses demonstrated a good fit for a one-factor model both with and without the cannabis use criterion and no differential criterion functioning was demonstrated across sex. The IRT model including the cannabis use criterion had discriminatory power comparable to the model without the cannabis use criterion and exceeded the informational value of the model without the cannabis use criterion in mild and moderate ranges of the severity continuum.

Discussion

Factor and IRT analyses disprove the validity of the DSM-IV abuse and dependence distinction: A single dimension represented the criteria rather than the two implied by the separate abuse/dependence categories. IRT models identified some dependence criteria to be among the mildest and some abuse criteria to be among the most severe—results inconsistent with the interpretation of DSM-IV cannabis abuse as a milder disorder or prodrome of cannabis dependence. The consumption criterion defined the mild end of the cannabis use disorder continuum and its excellent psychometric properties supported its consideration for inclusion in the next edition of DSM as a criterion for cannabis use disorders. Additional work is needed to identify candidate consumption criteria across all drugs that apply to the milder end of the severity continuum while also improving overall model performance and clinical diagnostic utility.     

Longitudinal study of cognition among adolescent marijuana users over three weeks of abstinence

Background

Cognitive deficits that persist up to a month have been detected among adult marijuana users, but decrements and their pattern of recovery are less known in adolescent users. Previously, we reported cognitive deficits among adolescent marijuana users after one month of abstinence (Medina, Hanson, Schweinsburg, Cohen-Zion, Nagel, & Tapert, 2007). In this longitudinal study, we characterized neurocognitive changes among marijuana-using adolescents across the first three weeks of abstinence.

Method

Participants were adolescent marijuana users with limited alcohol and other drug use (n = 19) and demographically similar non-using controls (n = 21) ages 15–19. Participants completed a brief neuropsychological battery on three occasions, after 3 days, 2 weeks, and 3 weeks of stopping substance use. Abstinence was ascertained by decreasing tetrahydrocannabinol metabolite values on serial urine drug screens. Verbal learning, verbal working memory, attention and vigilance, and time estimation were evaluated.

Results

Marijuana users demonstrated poorer verbal learning (p < .01), verbal working memory (p < .05), and attention accuracy (p < .01) compared to controls. Improvements in users were seen on word list learning after 2 weeks of abstinence and on verbal working memory after 3 weeks. While attention processing speed was similar between groups, attention accuracy remained deficient in users throughout the 3-week abstinence period.

Conclusions

This preliminary study detected poorer verbal learning and verbal working memory among adolescent marijuana users that improved during three weeks of abstinence, while attention deficits persisted. These results implicate possible hippocampal, subcortical, and prefrontal cortex abnormalities.     

Validation of the Cannabis Expectancy Questionnaire (CEQ) in adult cannabis users in treatment

Background

Outcome expectancies are a key cognitive construct in the etiology, assessment and treatment of Substance Use Disorders. There is a research and clinical need for a cannabis expectancy measure validated in a clinical sample of cannabis users.

Method

The Cannabis Expectancy Questionnaire (CEQ) was subjected to exploratory (n = 501, mean age 27.45, 78% male) and confirmatory (n = 505, mean age 27.69, 78% male) factor analysis in two separate samples of cannabis users attending an outpatient cannabis treatment program. Weekly cannabis consumption was clinically assessed and patients completed the Severity of Dependence Scale-Cannabis (SDS-C) and the General Health Questionnaire (GHQ-28).

Results

Two factors representing Negative Cannabis Expectancies and Positive Cannabis Expectancies were identified. These provided a robust statistical and conceptual fit for the data. Internal reliabilities were high. Negative expectancies were associated with greater dependence severity (as measured by the SDS) and positive expectancies with higher consumption. The interaction of positive and negative expectancies was consistently significantly associated with self-reported functioning across all four GHQ-28 scales (Somatic Concerns, Anxiety, Social Dysfunction and Depression). Specifically, within the context of high positive cannabis expectancy, higher negative expectancy was predictive of more impaired functioning. By contrast, within the context of low positive cannabis expectancy, higher negative expectancy was predictive of better functioning.

Conclusions

The CEQ is the first cannabis expectancy measure to be validated in a sample of cannabis users in treatment. Negative and positive cannabis expectancy domains were uniquely associated with consumption, dependence severity and self-reported mental health functioning.     

Demographic, emotional and social determinants of cannabis use in early pregnancy: the Generation R study

Aims

To ascertain demographic, emotional and social determinants of cannabis use in early pregnancy.

Design

This study was embedded in the Generation R study, a multiethnic population-based cohort of parents and their children, followed from pregnancy to childhood.

Setting

Rotterdam, The Netherlands.

Participants

Mothers enrolled in pregnancy who answered questions about their own and their partners substance use before and during pregnancy (n = 7610).

Measurements

Using self-report questionnaires, information was collected on maternal demographics, psychopathology, delinquency, childhood trauma, social stress, family functioning, and parental alcohol, tobacco and substance use. Multinomial logistic regression analysis was used, with non-using women as reference.

Findings

246 (3.2%) women used cannabis before pregnancy and 220 (2.9%) women used cannabis both before and during pregnancy. The strongest determinant for maternal cannabis use during pregnancy was cannabis use by the biological father of the child (OR = 38.56; 95%CI = 26.14–58.88). Maternal cannabis use during pregnancy was also independently associated with being single (OR = 4.25; 95%CI = 2.33–7.75) or having a partner without being married (OR = 2.75; 95%CI = 1.56–4.85), childhood trauma (OR = 1.39; 95%CI = 1.22–1.57) and delinquency (OR = 3.37; 95%CI = 1.90–5.98), but not with maternal age, ethnicity, psychopathology, family functioning and perceived stress. Being religious was protective (Islam: OR = 0.25; 95%CI = 0.09–0.65) for maternal cannabis use during pregnancy. Additionally, lower educational level determined continued cannabis use in ever-users (OR = 3.22; 95%CI = 1.54–6.74).

Conclusions

Our results showed that multiple demographic, emotional and social characteristics were associated with maternal cannabis use. These characteristics should be considered when investigating offspring exposed to cannabis in utero, as they may play an important role in mother–child interaction and child development.     

Is opioid substitution treatment beneficial if injecting behaviour continues?

Background

Opioid substitution treatment (OST) is recognised as an effective treatment for opioid dependence. Still, a subgroup of OST users continues to inject drugs. This study examines health risks and criminal activity in a population of needle exchange programme (NEP) participants by comparing those identified as current OST users to (i) those identified as former OST users and (ii) those with no OST experience.

Methods

This was a semi-annual cross-sectional study conducted from 2002 to 2011. NEP participants were interviewed in Oslo, Norway (n = 1760); 341 were identified as current OST users, 356 as former OST users and 1063 had no OST experience. The associations between OST status and health risk and criminal activity were assessed through univariate and multiple logistic regression analyses.

Results

Among NEP participants, those currently in OST had fewer non-fatal overdoses (OR = 0.5 [95% CI 0.3, 0.9]) compared to former OST users and those never in OST. Additionally, they were less likely to have injected frequently (OR = 0.4 [95% CI 0.3, 06]), to have used heroin daily or almost daily (OR = 0.3 [95% CI 0.2, 0.4]), and to have committed theft (OR = 0.6 [95% CI 0.4, 1.0]) and engaged in drug dealing (OR = 0.7 [95% CI 0.5, 0.9]) in the past month. Overall, there was a high level of polysubstance use and no group differences on this measure.

Conclusions

NEP participants who are currently in OST have substantially reduced health risks and criminal activity than other NEP participants. The high level of polysubstance use nevertheless poses a public health challenge.     

At high risk and want to quit: Marijuana use among adults with depression or serious psychological distress

Objectives

This study compared marijuana use characteristics and quit behaviors between adults with and without depression or serious psychological distress (SPD).

Methods

Drawing data for 39,133 non-institutionalized adults from the 2011 National Survey on Drug Use and Health, we assessed marijuana use status, frequent use, dependence or abuse, and quit behaviors in association with lifetime clinician-identified depression, lifetime and recent major depressive episode (MDE), and recent SPD.

Results

Adults with depression or SPD were at a significantly higher risk of being lifetime ever users (OR = 1.60–2.08), past year users (OR = 1.67–1.86), frequent users (OR = 1.40–1.62), and dependent or abusing users (OR = 2.32–3.05) compared with adults without these symptoms. Adults with depression or SPD had a lower quit ratio overall, but were equally or even more likely to make quit or self-regulation attempts. Further analysis suggested that adults with recent MDE had the greatest level of quit attempts or self-regulation attempts compared with adults without MDE or with past MDE.

Conclusions

These findings highlight the need for tailored cessation programs to sustain quit attempts and promote successful quitting among adults with depression or SPD, especially those with recent symptoms.     

Patterns of substance use among Argentinean adolescents and analysis of the effect of age at first alcohol use on substance use behaviors

Objective

The present study used an empirically based method to characterize substance use in a sample of Argentinean adolescents and analyzed the association between age at drinking onset and substance use behaviors. Differences in alcohol expectancies and personality traits as a function of different patterns of substance use were also explored.

Method

Data were obtained from 583 adolescents aged 13–18 years (M = 15.01 years; SD = 1.5 years; 59.5% female) from the city of Cordoba, Argentina. Alcohol, tobacco, and drug use and age at first alcohol use were measured. Personality traits, including extroversion, conscientiousness, impulsivity, and aggression, and positive and negative alcohol expectancies were assessed. Latent Class Analysis was applied to examine the structure of five co-occurring substance use behaviors: frequency of alcohol use, quantity of alcohol use, prevalence of drunkenness episodes, tobacco use, and drug use.

Results

Latent Class Analysis revealed five distinct patterns of substance use. The classes differed in substance use behaviors, personality traits, and alcohol expectancies. Adolescents with early drinking onset were more likely to show heavier alcohol use, more drunkenness episodes, and more drug use than adolescents with late drinking onset.

Conclusions

Latent Class Analysis allowed the detection of groups of adolescents with distinct patterns of substance use. These groups exhibited significantly different personality and alcohol expectancy profiles, likely representing subgroups who are at greater risk for developing alcohol-related problems.     

Methadone maintenance treatment may improve completion rates and delay opioid relapse for opioid dependent individuals under community corrections supervision

Aims

Several studies have demonstrated the importance of agonist therapies such as methadone and buprenorphine for preventing relapse for individuals being released from jail or prison to the community. No studies have examined the impact of methadone for increasing the completion of community supervision requirements and preventing opioid relapse for individuals under community corrections supervision. This observational study compared the community corrections completion rate and opioid relapse rate of individuals receiving methadone maintenance therapy (MMT) to individuals who did not.

Methods

Of the 2931 individuals enrolled under criminal justice supervision in the community, Treatment Accountability for Safer Communities (TASC), and who met criteria for opioid dependence, 329 (11%) individuals reported receiving MMT in the community.

Results

The majority of participants were White (79.8%) and male (63.5%), with a mean age of 31.33 years (SD = 9.18), and were under supervision for 10.4 months (SD = 9.1). MMT participants were less likely to fail out of supervision compared to individuals not in MMT (39.0% vs. 52.9%, p < 0.001), and had a lower rate of relapse (32.9%) and longer time to relapse (average days = 89.7, SD = 158.9) compared to the relapse rate (55.9%) and time to relapse (average days = 60.5, SD = 117.9) of those not on MMT.

Conclusions

While the observational nature of this study prevents causal inferences, these results suggest that utilization of MMT in community corrections may increase the likelihood of completing supervision requirements and delay time to opioid relapse. Providing agonist therapies to opioid dependent individuals under supervision appears to be a critical strategy in this important population.