Drug patterns in the chronic marijuana user

Onset of regular cannabis use and young adult insomnia: an analysis of shared genetic liability

STUDY OBJECTIVES

Estimate the genetic and environmental influences on the relationship between onset of regular cannabis use and young adult insomnia.

METHODS

In a population-based twin cohort of 1882 twins (56% female, mean age = 22.99, SD = 2.97) we explored the genetic/environmental etiology of the relationship between onset of regular cannabis use and insomnia-related outcomes via multivariate twin models.

RESULTS

Controlling for sex, current depression symptoms, and prior diagnosis of an anxiety or depression disorder, adult twins who reported early onset for regular cannabis use (age 17 or younger) were more likely to have insomnia (β = 0.07, p = 0.024) and insomnia with short sleep on weekdays (β = 0.08, p = 0.003) as young adults. We found significant genetic contributions for the onset of regular cannabis use (a2 = 76%, p < 0.001), insomnia (a2 = 44%, p < 0.001), and insomnia with short sleep on weekdays (a2 = 37%, p < 0.001). We found significant genetic correlations between onset of regular use and both insomnia (rA = 0.20, p = 0.047) and insomnia with short sleep on weekdays (rA = 0.25, p = 0.008) but no significant environmental associations between these traits.

CONCLUSIONS

We found common genetic liabilities for early onset of regular cannabis use and insomnia, implying pleiotropic influences of genes on both traits.

Onset of regular cannabis use and adult sleep duration: Genetic variation and the implications of a predictive relationship

BACKGROUND

Limited evidence suggests that early cannabis use is associated with sleep problems. Research is needed to understand the developmental impact of early regular cannabis use on later adult sleep duration.

METHODS

In a sample of 1656 adult twins (56% female, Mean age = 25.79yrs), linear mixed effects models were used to analyze the influence of retrospectively assessed age of onset of regular cannabis use on adult sleep duration controlling for sex, depression, and current substance use. Twin analyses provided genetic and environmental variance estimates as well as insights into the association and potential casual relationships between these traits.

RESULTS

Earlier age of onset for regular cannabis use was significantly associated with shorter adult sleep duration on both weekdays (β = -0.13, 95% CI = [-0.23, -0.04]) and weekends (β = -0.18, 95% CI = [-0.27, -0.08]). Additive genetics significantly contributed to the onset of regular cannabis use (a² = 76%, 95% CI = [68, 85]) and adult weekend sleep duration (a² = 20%, 95% CI = [11, 32]). We found evidence of a significant genetic correlation (r_A = -0.31, 95% CI = [-0.41, -0.15]) between these two traits and our best fitting model was consistent with early onset of regular cannabis use causing shorter adult weekend sleep duration (β = -0.11, 95% CI = [-0.18, -0.03]).

CONCLUSIONS

Our results are consistent with the hypothesis that early onset of regular cannabis use may have a negative impact on adult sleep duration.

Association between early onset of cigarette, alcohol and cannabis use and later drug use patterns: an analysis of a survey in European metropolises

OBJECTIVES

The study presents data about age of onset of alcohol, cigarette and cannabis use and investigates the association between age of onset and later drug use patterns.

METHODS

Using a sample from a cross-sectional multi-site study, personal interviews were conducted with 3,503 individuals aged 12-49 years. Last-month prevalence, age of onset and associations with subsequent use patterns were investigated.

RESULTS

Having started with cannabis before the age of 16 years was associated with an odds ratio of 1.6 for heavy cannabis use. For males, the odds ratio of heavy cannabis use was 1.7, when cannabis was already initiated by the age of 16. Heavy use of ecstasy, amphetamines, hallucinogens and cocaine is associated with use of cigarettes before 13 (OR = 1.9). For males, the odds ratio was 2.2 and for women 1.9.

CONCLUSIONS

Early use of alcohol, according to this data, does not seem to be related to subsequent heavy drug use. Early onset cannabis users show increasing probabilities of heavy use patterns. Preventive intervention programs have to start earlier than school-based programs normally do and specific developmental pathways need to be addressed.

Being stoned: a review of self-reported cannabis effects

Although there has been considerable research into the adverse effects of cannabis, less attention has been directed toward subjective effects that may be associated with ongoing cannabis use. Examination of self-reported cannabis effects is an important issue in understanding the widespread use of cannabis. While reviews have identified euphoria as a primary factor in maintaining cannabis use, relaxation is the effect reported most commonly in naturalistic studies of cannabis users, irrespective of the method used. Self-reported effects in 12 naturalistic and 18 laboratory studies were compared. Regardless of methodology there was considerable variation in the effects experienced. Variation has been reported in terms of opposite effects being experienced by different individuals, variation of effects by individuals within a single occasion and between occasions of use. Factors that might explain this variation are outlined. Limitations of the available literature and suggested directions for future research are discussed. [Green B, Kavanagh D, Young R. Being stoned: a review of self-reported cannabis effects.

Correlates of occasional cigarette and marijuana use: are teens harm reducing?

This paper examines characteristics that distinguish heavy and occasional cigarette and marijuana use among U.S. high school seniors. High school seniors who completed the 1994 Monitoring the Future survey (N = 15,929) were classified as nonusers, occasional users, and heavy users of cigarettes and marijuana. Level of use was examined with regard to degree of perceived risk of regular use, perceived risk of occasional use as well as several psychosocial factors previously shown to be associated with use (e.g., peer use, close friends' approval of use, and self-esteem). Involvement with other drugs and high-risk behaviors across levels of use was also examined. Heavy users of cigarettes or marijuana reported significantly lower perceived risk of regular use of each substance compared to occasional users. Heavy and occasional users did not generally differ with regard to perceived risk of occasional use. Compared to heavy users, occasional cigarette or marijuana users reported significantly lower rates of illicit drug use, heavy alcohol use, and high-risk driving behaviors as well as fewer problem behaviors and higher grades. Some adolescents may moderate their cigarette and marijuana use to minimize harmful effects they associate with heavier use (i.e., they may be practicing harm reduction). Additional research is needed to better understand controlled substance use, and incorporate this information into prevention and cessation programs.

Personality and non-medical use of drugs

A plethora of studies have indicated marihuana users differ from nonusers on a variety of personality dimensions. The direction of these differences and their interpretation vary from report to report depending on the samples, the measures, and the orientation of both authors and readers. The present study examined the relationships between extent of non-medical use of drugs and Personality Research Form (Jackson, 1974) scores of 24 males. Little evidence was found that would justify the acceptance of either a positive or a negative stereotype of a person who participates in non-medical drug use.

Dimensions of the subjective marijuana experience

A Drug History Questionnaire and a Marihuana Effects Questionnaire were completed by 91 male volunteers who were experienced marijuana smokers. A factor analysis was performed on the frequency of occurrence data for the Marihuana Effects Questionnaire. The resultant factors were similar to those reported previously in the literature supporting the existence of a stable, verbally definable marijuana experience. In comparison to the drug history variables of marijuana smokers in the late 1960s, our population showed increased multiple drug use, an earlier age of introduction to cannabis, and heavier use of cannabis. An analysis of the interaction of drug history variables with experienced marijuana effects suggested that the more frequently one uses cannabis, the less pronounced the experienced effects tend to be.

The avowal of motives for marijuana behavior

The present report is a comparative analysis of data from different studies on the motives avowed for the use and nonuse of marijuana. Qualitative data on the reasons given by users and nonusers for their behavior were first described and categorized according to 21 verbal patterns. Then these categories were utilized to analyze quantitative data by various investigators, i.e., were the means to compare the frequencies with which each kind of motive was verbalized. The results indicated that knowledge-ableness is by far the most frequently expressed motive for the initial use of marijuana. Continued use, however, is largely explained either on the grounds of self-fulfillment or with an appeal to psychological drives. Habitual users in different studies mentioned almost all categories of reasons for smoking more often than did occasional users. Explanations for the two types of nonuse were also quite dissimilar. For the discontinued use of pot, lack of interest is claimed as the chief motivation; but for never use, appeals to illegality, injury, drug addiction, and morality are asserted more frequently. Several conclusions based on these findings are drawn.