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whilst the legalization of marijuana for medical and recreational usage has raised issues about possible influences on marijuana use and philosophy among youth, couple of empirical studies have addressed this issue. We examined the relationship between medical marijuana patients and licensed growers per 1,000 population in 32 Oregon counties from 2006 to 2015, and marijuana use among youth on the exact same duration. We obtained information on subscribed medical marijuana patients and licensed growers from Oregon healthcare Marijuana Program and now we obtained data on youth marijuana usage, sensed parental disapproval, and demographic characteristics from the Oregon Healthy Teens Survey. Across 32 Oregon counties, the mean price of marijuana patients per 1,000 populace increased from 2.9 in 2006 to 18.3 in 2015, whereas the grower price increased from 3.8 to 11.9. Link between multi-level analyses indicated significant positive associations between prices of cannabis clients and growers per 1,000 populace and also the prevalence of previous 30-day cannabis usage, controlling for youth demographic characteristics. The cannabis client and grower prices were also inversely related to parental disapproval of cannabis usage, which reduced from 2006 to 2015 and acted as a mediator. These findings suggest that a greater number of registered marijuana patients and growers per 1,000 population in Oregon counties had been related to an increased prevalence of marijuana usage among youth from 2006 to 2015, which this relationship ended up being partially due to recognized norms favorable towards marijuana usage.

Keyword phrases: marijuana legalization, cannabis usage, adolescents


In the last few years there is an important move toward the legalization of marijuana in the usa. At the time of January 2017, it's legal for medical used in 28 states while the District of Columbia and for recreational use in eight states and also the District of Columbia (nationwide Conference of State Legislatures, 2017). The liberalization of marijuana rules raises general public health issues, especially associated with the possible results on cannabis use by adolescents. Marijuana use during adolescence happens to be related to a variety of negative effects, including increased threat of fatal automobile crashes (Asbridge, Hayden & Cartwright, 2012; Asbridge, et al., 2014); accidental injury, respiratory disease, and psychotic problems (Hall, 2009; Hall & Degenhardt, 2009); disability of intellectual functioning and mind development (Volkow, et al., 2016); and issues in adulthood like low academic attainment, greater danger of medication dependence, involvement in crime and incarceration (Chen, Storr, & Anthony, 2009; Green, Doherty, Stuart, & Ensminger, 2010; Hall & Degenhardt, 2009). Regardless of the possible dangers, cannabis is a widely utilized medication among adolescents. The 2015 Monitoring the near future survey shows that 35% of 12th graders and 25per cent of tenth graders reported previous 12 months cannabis use and 21percent and 15per cent, correspondingly, reported past 30 day usage (Johnston et al., 2016). About 80percent of 12th graders and 66percent of tenth graders reported that cannabis is “fairly easy” or “very easy” for. Just 32per cent of 12th graders and 43per cent of tenth graders observed “great risk” in regular cannabis use.

Although adolescents rarely obtain cannabis directly from medical dispensaries (Boyd, Veliz, & McCabe, 2015), the legalization of medical cannabis may nevertheless impact adolescents’ use by increasing its access through diversion from social sources, by fostering social norms being favorable to marijuana usage, or by reinforcing philosophy that cannabis use isn't harmful. Research on aftereffects of legalizing medical marijuana, however, is inconclusive. While some research reports have found positive associations between medical cannabis legalization and adolescents’ cannabis usage and associated thinking (e.g., Cerdá, Wall, Keyes, Galea, & Hasin, 2012; Schuermeyer, Salomonsen-Sautel, Price, et al., 2014; Stolzenberg, D’Alessio, & Dariano, 2016; Wen, Hockenberry, & Cummings, 2015; Willams & Bretteville-Jensen, 2014), other research reports have found no evidence of a relation between legalization and either adolescents’ cannabis usage or philosophy (age.g., Choo, et al., 2014; Hasin, et al., 2015; Lynne-Landsman, Livingston, & Wagenaar, 2013). Notably, but one research discovered that although dichotomous measures for the existence or lack of medical marijuana legalization were not related to increases in adolescents’ marijuana use, more nuanced measures taking into account certain conditions of medical cannabis rules (e.g., house cultivation is permitted) were pertaining to alterations in cannabis usage among adolescents (Pacula, Powell, Heaton, & Sevigny, 2015).

Concerns are often raised as to the nature associated with observed relationship involving the legalization of medical cannabis and adolescents’ usage. a national research making use of information from the nationwide domestic Survey on Drug Use and wellness from 2002 to 2008 discovered that the common past-month prevalence of marijuana use was 8.7% in states that had legalized medical marijuana and 6.9percent in other states (Wall et al., 2011). This research also found a significantly lower level of identified riskiness of cannabis usage among youth in states with legalized medical marijuana versus other states. These distinctions, but had been current before medical marijuana rules had been passed away. Other research reports have likewise unearthed that the distinctions in marijuana use and thinking between states with and without medical cannabis predate legalization (Hasin, et al. 2015; Wall, et al., 2016). These findings raise questions about whether use and identified danger had been affected by the legalization of cannabis for medical use or mirror pre-existing underlying distinctions on the list of states. In line with the second interpretation, a research by Friese and Grube (2013) found no association between the quantity of marijuana clients per 1,000 populace in Montana counties and youth marijuana use. However, the portion of voters supporting medical marijuana legalization in each county was definitely associated with life time and 30-day cannabis use by adolescents, suggesting that cannabis usage among youth might affected more by wider social norms favorable to marijuana legalization and make use of than by legalization by itself. Similarly, a recent nationwide study by Hasin et al. (2015) using information from the Monitoring the Future research from 1991 to 2014 additionally discovered greater prices of past-month cannabis usage and lower identified risk among youth staying in states before and after passing medical marijuana laws, but no changes in marijuana usage after medical cannabis laws had been passed.

Provided these inconclusive findings and interpretations, further research on relationship between medical marijuana legalization and adolescents’ marijuana usage and values will become necessary. In particular, small research has examined potential associations between increases in number of individuals utilizing cannabis for medical reasons and growing marijuana for medical usage, and cannabis usage among youth. Increases into the number of individuals using marijuana for medical reasons plus the number of licensed cannabis growers may also mirror alterations in norms favorable to cannabis use among adults, which could consequently be linked to normative thinking among youth. Therefore, legalization of medical cannabis might connected with marijuana use among youth directly or indirectly through changes in values that cannabis usage is acceptable and normative.

Our study further investigates possible associations between medical marijuana legalization and marijuana usage among youth by examining mechanisms through which legalization may influence this behavior. We examined alterations in how many registered medical cannabis clients and licensed growers in Oregon counties from 2006 to 2015 as indicators of norms favorable to cannabis usage, additionally the associations between county-level rates of registered medical marijuana patients and licensed growers and styles in marijuana usage and normative values (in other words., identified parental disapproval of cannabis use) among Oregon youth. We also examined whether perceived parental disapproval of marijuana usage may mediate the associations among medical marijuana patients, growers and cannabis use. We hypothesized that increases in prices of medical cannabis clients and licensed growers within county level could be connected with increases in prevalence of marijuana use among youth and inversely associated with perceived parental disapproval of marijuana use. We additionally hypothesized that observed parental disapproval of cannabis use would mediate relationships between county-level prices of medical marijuana clients, licensed growers and cannabis use among youth.


Data Sources and Measures

Medical Marijuana people and Growers

We obtained county-level counts of subscribed medical cannabis clients and licensed growers from Oregon health Marijuana Program office, which began reporting these details in 2005 for clients and in 2006 for growers, subsequent to the legalization of cannabis for medical use within 1998. On the basis of the availability of student-level information from the Oregon Healthy Teens Survey, we secured patient and grower counts for 32 Oregon counties from 2006 to 2015. We additionally obtained corresponding county population information for every single of those years from the Portland State University Center for Public and Urban Affairs Population Research Center (Portland State University, 2016). We then computed rates for amount of medical marijuana patients/1,000 population and licensed growers/1,000 populace for every single county and year.

Oregon healthier Teens Survey

We obtained survey information for 8th and 11th grade students from the statewide Oregon Healthy Teens Survey (OHT), that has been administered yearly from 2006 to 2009, plus in 2011, 2013 and 2015 (Oregon Health Authority, 2016). The OHT is an anonymous, voluntary self-administered survey modeled after the Youth Risk Behavior Survey (YRBS) and Student Drug Use Survey that were formerly administered in Oregon.

The OHT is conducted during springtime semester from February through might on scannable kinds administered by trained teachers in classrooms. Pupils never compose any private information in the survey form, and completed studies are put into an envelope. The OHT survey takes about 40 minutes to accomplish.

The OHT sampling framework is dependant on the YRBS, and comprises general public center and high schools sampled within each county. The test is intended to be representative of 8th and 11th graders in each county together with state. Post-hoc sample loads had been developed for every county and also the state on the basis of the real amount of 8th and 11th graders in each school, county together with entire state (OHA, 2016).

Marijuana usage

From 2006 to 2013, youth had been expected how many times they utilized marijuana may be the previous thirty days, with six feasible reaction choices from “zero times” to “40 or maybe more times.” In 2015, issue had been, “During days gone by thirty days, how many days did you utilize cannabis?” with five reaction choices from “0 days” to “10 or more days.” Because over 80% of respondents indicated no past 30-day utilization of cannabis in each survey 12 months, a dichotomous measure for just about any past 30-day use is made for every OHT 12 months.

Normative Beliefs

From 2006 to 2015, youth were asked, “How incorrect do your parents feel it will be for you to smoke cigarettes cannabis?” with four possible reactions ranging from “Not anyway wrong” to “Very incorrect.”


Youth reported how old they are, gender, ethnicity (Hispanic/non-Hispanic) and competition, which was addressed as a dichotomous adjustable (0 = non-White, 1 = White) because over 80per cent of participants indicated their competition as white generally in most survey years.

Information Analysis

Descriptive data had been first obtained for many research variables by study 12 months using post-hoc sample loads given the OHT information sets. Because student-level observations (level 1) were nested within counties (degree 2), multi-level logistic and linear regression analyses were conducted in HLM version 7.0 software, allowing for random effects at the county degree to adjust for nesting (Raudenbush et al., 2011). We first conducted analyses individually for 8th and 11th graders to examine possible relationships between improvement in the price of medical marijuana patients and growers per 1,000 population and also the prevalence of previous 30-day cannabis use and parental disapproval of cannabis use over time. Two-level models included a cross-level study 12 months × cannabis clients (and growers)/1,000 populace conversation term and corresponding primary impacts, and demographic characteristics as covariates. Inclusion associated with cross-level survey 12 months × marijuana clients (and growers)/1,000 populace connection term allowed united states to look at whether changes in previous 30-day cannabis use and parental disapproval of cannabis use in the long run had been moderated by the county-level price of authorized medical cannabis patients and growers/1,000 population. Nonsignificant interactions had been dropped from regression models. We also examined differences in the annual prevalence of past 30-day cannabis usage and parental disapproval of cannabis use with time in counties categorized by high, medium and low rates of authorized medical cannabis patients and growers/1,000 populace. Multi-level logistic regression models were also set you back examine the extent to which parental disapproval of cannabis use may have acted as a mediator. Significant associations between your rate of marijuana patients or growers/1,000 population and parental disapproval of cannabis usage coupled with a decrease in the associations between past 30-day cannabis use and these county-level prices after including parental disapproval of cannabis use in the models would provide evidence for mediation (MacKinnon & Dwyer, 1993). We evaluated the importance of indirect associations utilising the Sobel Test (MacKinnon & Dwyer, 1993). As the outcomes had been quite similar for 8th and 11th graders, we went equivalent regression models controlling for grade the total test and report those results.


Sample Characteristics

Sample characteristics by survey year are provided in dining table 1. The state-level prevalence of marijuana use changed little within the 10-year period. The prevalence price for past 30-day cannabis use was roughly 14per cent in 2015, and had been reduced among eighth-graders (9%) than 11th graders (20%). Youth reported a rather high level of parental disapproval of marijuana use across all survey years. The mean price of cannabis patients per 1,000 county population increased significantly from 2.9 in 2006 (range: 0 – 10.9) to 18.3 in 2015 (range: 5.7 – 44.9). The mean rate of certified cannabis growers also increased from 3.8 (range: 0 – 13.1) in 2006 to 11.9 (range: 4.7 – 28.2) in 2015.

Table 1

Sample traits by year, suggest (SD) or percent1

Variable2006 (N=25,967)2007 (N=26,448)2008 (N=28,346)2009 (N=14,338)2011 (N=11,600)2013 (N=28,540)2015 (N=29,819)Any previous thirty day cannabis usage (per cent)14.313.613.816.415.915.413.9Demographic traits Age15.1 (1.5)15.0 (1.5)15.1 (1.5)15.2 (1.6)15.2 (1.6)15.1 (1.6)15.1 (1.6) Male50.448.948.548.751.349.649.8 Hispanic14.517.817.819.717.722.825.1 White74.584.785.484.586.485.286.6Parental disapproval of cannabis use3.7 (0.6)3.7 (0.6)3.7 (0.7)3.7 (0.7)3.6 (0.7)3.6 (0.8)3.6 (0.8)Marijuana patients/1,000 county population2.9 (2.7)3.9 (3.4)5.5 (3.6)5.4 (3.3)16.0 (7.9)16.4 (9.5)18.3 (8.9)Marijuana growers/1,000 county population3.8 (3.4)4.3 (3.2)5.4 (3.4)7.0 (3.9)12.6 (6.2)15.3 (10.4)11.9 (5.3)Open in a separate window1Survey test sizes are unweighted, but descriptive statistics were acquired with state sample weights.

Multi-level Analyses

As noted above, we at first ran separate multi-level regression analyses for 8th and 11th graders. As the results were quite similar for 8th and 11th graders, we went similar regression models controlling for grade for the total test and report those results.

Outcomes of multi-level logistic regression analyses for previous 30-day cannabis use are provided in dining table 2. The study 12 months × cannabis clients and growers per 1,000 population conversation terms are not statistically significant in initial regression models, and were therefore dropped from analyses. Both the rate of cannabis patients and growers per 1,000 populace were absolutely associated with the prevalence of past 30-day cannabis use, managing for youth demographic characteristics. Odds ratios indicate that all additional marijuana patient or grower is related to a one % boost in the prevalence of marijuana use among youth. These relationships were further analyzed by classifying counties based on the normal price of cannabis patients and growers per 1,000 from 2006 to 2015, and plotting styles in previous 30-day marijuana use for counties dropping into low, medium and high categories. Around one-third for the counties fell into each category. Figure 1 shows generally higher degrees of cannabis usage over the 10-year period among youth in counties with greater rates of medical marijuana clients per 1,000 populace; this pattern was much the same for kinds of marijuana growers per 1,000 population.

Open in a separate windowFigure 1

Past 30-day cannabis use prevalence by rate of marijuana patients per 1,000 county populace, adjusted for age, sex, and race/ethnicity. The marijuana clients per 1,000 populace groups (ranges) are low (1.9 – 6.3), medium (7.1 – 8.8), and high (9.2 – 56.1).

Table 2

Multi-level logistic regression models predicting any past 30-day marijuana use, chances ratio (95per cent confidence interval)

VariableModel 1Model 2Student level Age1.32 (1.27, 1.38)**1.32 (1.27, 1.38)** Male1.16 (1.07, 1.25)**1.16 (1.07, 1.25)** Hispanic1.32 (1.14, 1.53)**1.32 (1.14, 1.53)** White1.01 (0.81, 1.28)1.01 (0.81, 1.28) Survey year1.00 (0.99, 1.01)1.00 (0.99, 1.01)County level Marijuana patients/1,0001.01 (1.005, 1.02)**--- Marijuana growers/1,000---1.01 (1.004, 1.02)**Open in a different screen**p < .01.

Results of the multi-level linear regression analyses for identified parental disapproval of cannabis use are supplied in dining table 3. The study year × marijuana patients and growers per 1,000 population interaction terms are not notably linked to perceived parental disapproval of marijuana usage and were dropped from subsequent analyses. The rate of marijuana clients and growers per 1,000 populace were inversely connected with recognized parental disapproval of marijuana use, managing for youth demographic characteristics. These relationships are illustrated in Figure 2, which indicates reduced levels of parental disapproval in counties with greater rates of medical cannabis clients per 1,000 population, and a downward slope for counties in all three categories of cannabis clients per 1,000 population from 2006 to 2015. This pattern was virtually identical for kinds of cannabis growers per 1,000 populace. Mean parental disapproval values for decades once the OHT had not been administered (2010, 2012, 2014) were averaged from previous and following 12 months.

Open in a different windowFigure 2

Perceived parental disapproval of cannabis usage by rate of marijuana clients per 1,000 county population, adjusted for age, sex, and race/ethnicity. The cannabis patients per 1,000 populace categories (ranges) are low (1.9 – 6.3), medium (7.1 – 8.8), and high (9.2 – 56.1).

Table 3

Multi-level linear regression models predicting parental disapproval of cannabis usage, beta (standard mistake)

VariableModel 1Model 2Student level Age−.062 (.002)**−.062 (.002)** Male−.029 (.007)**−.029 (.007)** Hispanic.007 (.011).007 (.011) White−.015 (.009)−.015 (.009) Survey year−.018 (.0009)**−.018 (.0009)**County level Marijuana patients/1,000−.004 (.001)**--- Marijuana growers/1,000---−.003 (.0009)**Open in a separate window**p < .01.

Results associated with the multi-level regression analysis (dining table 4) suggest your associations between marijuana patients and growers per 1,000 populace were attenuated, but stayed statistically significant whenever observed parental disapproval had been contained in the regression models, supplying proof for partial mediation. Sobel tests indicated that the indirect associations between marijuana patients and growers per 1,000 population and previous 30-day marijuana use through sensed parental disapproval of marijuana use had been significant, z = 4.00, p < .001. Needlessly to say, identified parental disapproval ended up being inversely related to any previous 30-day cannabis usage.

Table 4

Multi-level logistic regression models to assess mediating effects of parental disapproval of cannabis use, odds ratio (95% self-confidence period)

VariableModel 1Model 2Student level Age1.26 (1.22, 1.30)**1.26 (1.22, 1.30)** Male1.10 (1.03, 1.18)**1.10 (1.03, 1.18)** Hispanic1.42 (1.26, 1.61)**1.42 (1.26, 1.61)** White1.00 (0.84, 1.21)1.00 (0.84, 1.21) Survey year0.97 (0.96, 0.99)*0.97 (0.96, 0.99)* Parental disapproval of marijuana use0.34 (0.33, 0.35)**0.34 (0.33, 0.35)**County level Marijuana patients/1,0001.006 (1.001, 1.01)*1.006 (1.002, 1.01)** Marijuana growers/1,000------Open in another window*p<.05.**p < .01.


Our findings suggest that greater prices of authorized medical marijuana patients and licensed growers per 1,000 population in Oregon counties are related to an increased prevalence of marijuana use among adolescents residing in those counties. However, our expectation that increases in prices of marijuana patients and growers per 1,000 population could be related to increases into the prevalence of marijuana use among youth wasn't supported. Results also indicated reduced levels of parental disapproval of cannabis use in counties with higher prices of medical cannabis patients and growers, and decreases in sensed parental disapproval of marijuana usage across all 32 Oregon counties from 2006 to 2015. Our findings further suggest that the associations between rates of medical cannabis patients and growers per 1,000 population and previous 30-day marijuana usage had been partially mediated through perceived norms favorable to cannabis usage.

The substantial increases in subscribed medical marijuana clients and licensed growers in Oregon may mirror a growing acceptance of cannabis as a treatment for chronic pain, as this is the most typical reason for referral and enrollment (OMMP, 2016). This upward trend may carry on with the legalization of cannabis for recreational use in 2014, therefore the opening of local dispensaries over the suggest that provide cannabis for both medical and leisure usage.

Just like two recent national studies (Hasin et al., 2015; Wall et al., 2011) our findings indicated higher quantities of cannabis use and identified norms favorable towards marijuana use from 2006 to 2015 in counties because of the highest prices of marijuana patients and growers per 1,000 population. This might indicate mechanisms by which legalization of marijuana for medical and leisure usage may contribute to marijuana usage among youth. In particular, youth might prone to utilize marijuana if they are exposed to more grownups who put it to use plus don't disapprove of marijuana use. Marijuana normally more prone to be around through commercial and social sources after legalization for medical or leisure usage, and subsequent increases in number of medical cannabis patients, recreational users, and growers that do not need a license.

Findings of this study should be considered in light of a few possible restrictions. First, the types of adolescents who participated in the Oregon healthier Teens Survey (OHT) from 2006 to 2015 may not be representative of all of the adolescents in Oregon or the Oregon counties included in this study. Change in the frequency of OHT management after 2009 could have influenced our outcomes, though OHT study year was included as a covariate in multi-level regression analyses. Single-item measures of marijuana usage and normative values may not have adequate reliability and legitimacy. Self-report study concerns may also be subject to remember and social desirability biases (e.g., underreporting marijuana use), though prior research reports have shown that self-reported measures of drug usage among adolescents have good validity and dependability (Bachman et al., 2011). Regrettably, potentially critical indicators pertaining to marijuana usage (age.g., perceived accessibility to cannabis, perceived cannabis use among friends and adults, cannabis sources) were not included in the OHT from 2006 to 2015. Mediation analyses had been restricted to the cross-sectional design regarding the research and reporting of sensed parental disapproval of marijuana use by adolescents in the place of their parents. Finally, the amount of authorized medical marijuana clients and growers reported for Oregon counties doesn't accurately mirror the amount of people in each county illicitly making use of or growing cannabis.

Further research is had a need to better understand whether and exactly how the legalization of cannabis for medical and leisure usage may influence sensed norms and availability of cannabis and marijuana use among youth. Additional longitudinal studies are essential to evaluate the consequences of cannabis legalization policies and enforcement tasks on marijuana accessibility, usage and associated consequences, such as driving while reduced and co-use of marijuana with liquor alongside medications. Such research will enhance our understanding of the potentially negative effects of cannabis legalization among youth, and determine effective prevention strategies.


This research and preparation with this paper were supported by a grant from nationwide Institute on Alcohol Abuse and Alcoholism (R01AA021726). This content is entirely the duty for the authors and does not necessarily express the state views of NIAAA and/or National Institutes of Health. We would like to thank Emma and Zachary Adler as well as for assisting with the purchase and compilation of medical cannabis client and grower data through the Oregon healthcare Marijuana Program.



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