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PubMed2000

The influence of early and frequent use of marijuana on the risk of desistance and of progression to marijuana-related harm.

BACKGROUND: A significant minority of lifetime marijuana users will eventually receive a diagnosis of abuse or dependence. Yet little is known regarding the effect of age at onset and frequency of lifetime marijuana use on desistance from use and on progression to marijuana disorders. METHODS: To address this issue, data were obtained from a community sample of 2,729 lifetime marijuana users participating in the Ontario Mental Health Supplement. RESULTS: Early and frequent lifetime marijuana use was associated with highly persistent use and rapid progression to marijuana-related harm. Multivariate analyses revealed a monotonic increase in the risk of desistance with less frequent categories of use and later ages of onset. Results also indicated a threshold of use (100-199 times) associated with an elevated risk of developing marijuana disorders. A lower threshold of risk for marijuana problems was observed for females (50-99 times). CONCLUSIONS: Early and frequent marijuana use are potent risk factors for prolonging desistance and hastening marijuana-related harm. Required are prevention programs aimed at delaying the onset of first use as well as harm reduction strategies that encourage cessation or reduced levels of consumption among those already using.

Adolescent↗
PubMed2006

Discrete opioid gene expression impairment in the human fetal brain associated with maternal marijuana use.

Fetal development is a period sensitive to environmental influences such as maternal drug use. The most commonly used illicit drug by pregnant women is marijuana. The present study investigated the effects of in utero marijuana exposure on expression levels of opioid-related genes in the human fetal forebrain in light of the strong interaction between the cannabinoid and opioid systems. The study group consisted of 42 midgestation fetuses from saline-induced voluntary abortions. The opioid peptide precursors (preprodynorphin and preproenkephalin (PENK)) and receptor (mu, kappa and delta) mRNA expression were assessed in distinct brain regions. The effect of prenatal cannabis exposure was analyzed by multiple regression controlling for confounding variables (maternal alcohol and cigarette use, fetal age, sex, growth measure and post-mortem interval). Prenatal cannabis exposure was significantly associated with increased mu receptor expression in the amygdala, reduced kappa receptor mRNA in mediodorsal thalamic nucleus and reduced preproenkephalin expression in the caudal putamen. Prenatal alcohol exposure primarily influenced the kappa receptor mRNA with reduced levels in the amygdala, claustrum, putamen and insula cortex. No significant effect of prenatal nicotine exposure could be discerned in the present study group. These results indicate that maternal cannabis and alcohol exposure during pregnancy differentially impair opioid-related genes in distinct brain circuits that may have long-term effects on cognitive and emotional behaviors.

Adult↗
PubMed1999

Comparative epidemiology of initial drug opportunities and transitions to first use: marijuana, cocaine, hallucinogens and heroin.

The earliest stages of involvement with illicit drugs have been understudied. In a recent report, we examined initial opportunities to try marijuana and transitions from first opportunity to first use of that drug. This report extends that work by investigating early involvement with cocaine, heroin, and hallucinogens as well. We examine sex and race ethnicity differences in estimates of having a drug opportunity, and in the probability of progressing from having an opportunity to try a drug to actually using the drug. Self-report interview data collected for the National Household Surveys on Drug Abuse (NHSDA) from 1979 to 1994 were analyzed. Results showed that an estimated 51% of US residents have had an opportunity to try marijuana; comparative estimates for cocaine, hallucinogens, and heroin are 23, 14, and 5%, respectively. Among those who eventually used each drug, the vast majority made the transition from first opportunity to first use within 1 year. Males were more likely than females to have opportunities to try these drugs, but were not more likely than females to progress to actual use once an opportunity occurred. Time trends indicate recent increases from 1990 to 1994 in the estimated probability of using an illicit drug once an opportunity occurs, particularly for hallucinogens. Exploratory analyses on race ethnicity yielded some interesting leads for future research. This study sheds light on the epidemiology of the earliest stages of drug involvement in the USA. Implications for prevention efforts and for our understanding of sex differences in drug involvement are discussed.

Adolescent↗
PubMed1995

A longitudinal study of prenatal marijuana use. Effects on sleep and arousal at age 3 years.

OBJECTIVE: To test the hypothesis that sleep disruptions would be evident in 3-year-old children with a history of prenatal marijuana exposure. DESIGN: A prospective study using stratified random sampling beginning in the fourth month of pregnancy. Marijuana and other substance use were assessed by interviews at multiple time points. Offspring were followed up through age 3 years with multidomain assessments at fixed time points, including electroencephalographic sleep studies in the newborn period and at age 3 years. SETTING: Primary care, prenatal clinic at a university hospital. SUBJECTS: The sample included 18 children with prenatal marijuana exposure (mean [+/- SD] age, 39.0 +/- 4.4 months) and 20 control children (mean [+/- SD] age, 39.7 +/- 4.4 months). The two groups were similar in relationship to maternal age, race, income, education, or maternal use of alcohol, nicotine, and other substances in the first trimester. MAIN OUTCOME MEASURE: Sleep variables from polysomnographic recordings at age 3 years. RESULTS: Children with prenatal marijuana exposure showed more nocturnal arousals (mean [+/- SD], 8.2 +/- 5.3 vs 3.2 +/- 4.6; P < .003), more awake time after sleep onset (mean [+/- SD], 27.4 +/- 20.0 vs 13.7 +/- 12.4 min; P < .03), and lower sleep efficiency (mean [+/- SD], 91.0 +/- 3.8 vs 94.4 +/- 2.1; P < .03) than did control children. CONCLUSION: Prenatal marijuana exposure was associated with disturbed nocturnal sleep at age 3 years.

Adolescent↗
PubMed1983

The availability and current use of marijuana among adults.

The bulk of previous research on marijuana use shares three common features. First, it focuses on "high-risk" student or adolescent populations. Second, researchers have emphasized the "ever-used" category of marijuana use. Third, reported use rates are generally based on the percentage of users in the total population of interest. By using the total population as the denominator when calculating use rates, researchers assume that everyone has an equal opportunity to smoke marijuana. This paper suggests using a use-availability ratio to adjust for potential access to marijuana and to determine which segments of the population are "high risk."

Adult↗
PubMed1985

Marijuana use and psychiatric illness: a follow-up study.

In 1970, 100 regular marijuana users and 50 of their nonuser friends underwent a psychiatric evaluation. Of these, 97 users and all 50 nonusers were reinterviewed 6-7 years later. At follow-up, 60% of both groups had a psychiatric diagnosis. Antisocial personality was more prevalent in users; otherwise, there were no significant differences in diagnosis. Depression, alcohol abuse, and antisocial personality increased in users. However, these increases occurred in subjects who had reported problems in these areas in the initial interview but did not then meet diagnostic criteria. There was not a significant increase in the total number with a diagnosable illness.

Adolescent↗
PubMed1976

Neuropsychologic, intellectual, and personality correlates of chronic marijuana use in native Costa Ricans.

The present cross-cultural study investigated the effects of chronic marijuana usage on higher adaptive brain functions and personality in native Costa Ricans. After extensive standardization in Costa Rica, a battery of neuropsychologic, intelligence, and personality tests was administered to two carefully matched groups of marijuana users and controls (NU = NC = 41). Multivariate analyses of multiple combinations of variables, followed by separate univariate tests on each measure, revealed essentially no significant differences between users and nonusers on any of the neuropsychologic, intelligence, or personality tests. Furthermore, no relationship was found between level of daily use (high vs low) and test performance. These findings were discussed in terms of previous chronic and acute studies of changes in adaptive brain functions and personality as a function of marijuana intake.

Adolescent↗
PubMed2004

Early adolescent through young adult alcohol and marijuana use trajectories: early predictors, young adult outcomes, and predictive utility.

The present study takes a developmental approach to subgrouping and examines the trajectories of substance use from early adolescence through young adulthood among a community sample of 481 individuals. The patterns of use were examined, subgroups were identified separately for men and women and for alcohol and marijuana, and psychosocial predictors and psychopathology outcomes that differentiated the groups were identified. The results revealed three substantially overlapping subgroups for both alcohol and marijuana: early onset, late onset, and nonuser. Although the general patterns of which dependent variables were related to group were similar for alcohol and marijuana, a closer examination revealed important subgroup differences. For alcohol use, the early-onset group was more dysfunctional in terms of predictors and outcomes whereas the late-onset and nonuser groups were better adjusted. In contrast, for marijuana, the early- and late-onset groups were both more dysfunctional than the nonuser group. In a final analysis, we examined the predictive utility of our developmental approach to subgrouping compared to a traditional, static approach.

Adolescent↗
PubMed2006

Motivational enhancement therapy for adolescent marijuana users: a preliminary randomized controlled trial.

This study's aims were (a) to investigate the feasibility of a school-based motivational enhancement therapy (MET) intervention in voluntarily attracting adolescents who smoke marijuana regularly but who are not seeking formal treatment and (b) to evaluate the efficacy of the intervention in reducing marijuana use. Ninety-seven adolescents who had used marijuana at least 9 times in the past month were randomly assigned to either an immediate 2-session MET intervention or to a 3-month delay condition. Two thirds of the sample characterized themselves as in the precontemplation or contemplation stages of change regarding marijuana use. Participants' marijuana use and associated negative consequences were assessed at baseline and at a 3-month follow-up. Analyses revealed that both groups significantly reduced marijuana use at the 3-month follow-up ( p = .001); however, no between-group differences were observed. Despite the absence of a clear effect of MET, this study demonstrated that adolescents could be attracted to participate in a voluntary marijuana intervention that holds promise for reducing problematic levels of marijuana use.

Adolescent↗
PubMed1990

Personality and alcohol and marijuana use: patterns of convergence in young adulthood.

This study looks at similarities and differences between users of alcohol only and users of both alcohol and marijuana ranging in age from 18 to 24. Assessment of use included measures of use intensity, use context, use functions, and use problems. Personality variables included measures of temperamental/affective tendencies, evaluative appraisals of self, and stress associated with negative appraisals of one's self and one's environment. The two strongest patterns of convergence were found to be similar across groups and to be consistent with mean differences between both groups. It is concluded that the two patterns characterize different segments of the population of users.

Adolescent↗