To critically review cannabis research during the past 10 years in relation to rates of use, behavioral problems, and mental disorders in young people.
Studies published in English between 1994 and 2004 were identified through systematic searches of literature databases. The material was selectively reviewed focusing on child and adolescent data.
In the 27 years between 1976 and 2002, approximately half of all 12th graders had been exposed to cannabis in the United States. There is growing evidence that early and regular marijuana use is associated with later increases in depression, suicidal behavior, and psychotic illness and may bring forward the onset of schizophrenia. Most of the recent data reject the view that marijuana is used to self-medicate psychotic or depressive symptoms. Research on treatment is very limited.
Research on the mental health effects of cannabis has increased dramatically. Although doubts still remain about the role of cannabis in the causation of juvenile psychiatric disorder, the weight of the evidence points in the direction of early and regular cannabis use having substantial negative effects on psychosocial functioning and psychopathology.
"Among adolescent cannabis users, initiation seems to peak at age 15 (Monshouwer et al., 2005). At the same time, cannabis involvement has been related to several adverse outcomes , including other illicit drug use, poor school performance and early dropout, crime and mental health problems including depression, psychosis and substance use disorders, that seem most pronounced in adolescents who start using cannabis before age 16 (Arseneault et al., 2002; Fergusson et al., 2002; Lynskey and Hall, 2000; Rey et al., 2004). Research on initiation of cannabis use before age 16 can improve our understanding of a developmental pathway that may end with such serious adverse outcomes. "
"Using the Medline search string [(cannabi* OR marijuana OR marihuana OR weed OR hash) AND (“risk factor*” OR “predict*” OR associat*) AND (harm OR problem* OR dependenc* OR abus*)], 3187 publications between January 1, 2000 and March 1, 2014 were identified, including 382 review articles. Among the associations covered in these publications are those between cannabis and genetic and/or environmental factors , stress , other mental health disorders  including juvenile psychiatric disorders ; the link between cannabis and psychosis/schizophrenia , , neurocognitive  and neuroanatomical  correlates of cannabis use, between cannabis and socioeconomic status , and early onset of cannabis use . A number of studies specifically assessed associations between use quantity and cannabis abuse/dependence , . "
[Show abstract][Hide abstract] ABSTRACT: Introduction:
Cannabis is Europe's most commonly used illicit drug. Some users do not develop dependence or other problems, whereas others do. Many factors are associated with the occurrence of cannabis-related disorders. This makes it difficult to identify key risk factors and markers to profile at-risk cannabis users using traditional hypothesis-driven approaches. Therefore, the use of a data-mining technique called binary recursive partitioning is demonstrated in this study by creating a classification tree to profile at-risk users.
59 variables on cannabis use and drug market experiences were extracted from an internet-based survey dataset collected in four European countries (Czech Republic, Italy, Netherlands and Sweden), n = 2617. These 59 potential predictors of problematic cannabis use were used to partition individual respondents into subgroups with low and high risk of having a cannabis use disorder, based on their responses on the Cannabis Abuse Screening Test. Both a generic model for the four countries combined and four country-specific models were constructed.
Of the 59 variables included in the first analysis step, only three variables were required to construct a generic partitioning model to classify high risk cannabis users with 65-73% accuracy. Based on the generic model for the four countries combined, the highest risk for cannabis use disorder is seen in participants reporting a cannabis use on more than 200 days in the last 12 months. In comparison to the generic model, the country-specific models led to modest, non-significant improvements in classification accuracy, with an exception for Italy (p = 0.01).
Using recursive partitioning, it is feasible to construct classification trees based on only a few variables with acceptable performance to classify cannabis users into groups with low or high risk of meeting criteria for cannabis use disorder. The number of cannabis use days in the last 12 months is the most relevant variable. The identified variables may be considered for use in future screeners for cannabis use disorders.
PLoS ONE 09/2014; 9(9):e108298. DOI:10.1371/journal.pone.0108298 · 3.23 Impact Factor
"Underage drinking and illicit drug use are common and serious health problems among college students (Caldeira, Arria, O'Grady, Vincent, & Wish, 2008; Johnston, O'Malley, Bachman, & Schulenberg, 2011) and are related to a multitude of adverse consequences (Brook, Adams, Balka, & Johnson, 2002; Fergusson, Horwood, & Swain-Campbell, 2002; Ham & Hope, 2003; Miller, Naimi, Brewer, & Jones, 2007; Rey, Martin, & Krabman, 2004). The risk for substance use initiation and subsequent manifestation of substance use disorder (SUD) 1 is high during late adolescence (Bachman, Wadsworth, O'Malley, Johnson, & Schulenberg, 1997; Chen & Kandel, 1995), and vulnerability is highly influenced by macro-level (e.g., availability, drug and alcohol laws, outlet density), intermediate level (e.g., parents, peers, religion, external stressors), and micro-level (e.g., alcohol expectancies, personality traits, genetics) risk and protective factors (Hasin & Katz, 2010). "
[Show abstract][Hide abstract] ABSTRACT: Substance use disorder is a serious health problem that tends to manifest in late adolescence. Attempting to influence targetable risk and protective factors holds promise for prevention and treatment. Survey data from 1253 college students (48.5% male, 26.9% non-White) were used to investigate the independent and combined effects of two prominent factors, sensation seeking and parental monitoring, on the probability of alcohol and/or cannabis dependence during the first year of college. In multivariate analyses that controlled for high school use, gender, race, mother's education, and importance of religion, retrospective reports by the student of parental behavior during the last year of high school indicated that higher levels of parental monitoring had a direct effect on reducing risk for alcohol dependence during the first year of college, but not on cannabis dependence. High levels of sensation seeking were associated with increased risk for both alcohol and cannabis dependence. No interaction effects were found. The results extend prior findings by highlighting influences of pre-college parental monitoring and sensation seeking on the probability of alcohol and/or cannabis dependence during the first year of college. The findings also suggest that these two factors are useful in identifying college students at high risk for alcohol and/or cannabis dependence.
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