Use of Marijuana and Changing Risk Perceptions Ray M. Merrill, PhD, MPH, MS, FAAHB, FACE Objectives: To improve understanding of which adolescents were most likely to perceive marijuana as not harmful. Methods: Analyses were based on the SHARP survey, conducted in 3 large school districts in Utah in 2009, 2011, and 2013, among students in grades 6, 8, 10, and 12. Results: Across school grades, students who viewed marijuana as not harmful were ≥9 times more likely to have used marijuana. The perception that marijuana has no risk was higher in males, His-
M
arijuana (the dried leaves, flowers, stems, and seeds from the hemp plant Cannabis sativa) is the most commonly used illicit drug in the United States.1 In 2013, 22.7% of high school seniors used marijuana in the past 30 days, representing an increase of 3.3% from 2008.2 An increase in marijuana use also was observed in earlier school grades. This increase paralleled decreasing perceived risk of harm associated with marijuana use.2 The changing perception of risk is likely supported by legalization of medical marijuana in 23 states and the District of Columbia, and legalization of recreational marijuana use in 4 states and the District of Columbia in the US as well as in other countries throughout the world.1,3,4 Softening risk perceptions of marijuana use is expanding despite the fact that there remains much that we do not know about the health effects of the drug. At least 489 chemical compounds, with 70 unique to the cannabis plant, have been identified in marijuana.5 Cannabis is chemically complex due to the vast number of its constituents and their possible interaction with one another.6 We do know that tetrahydrocannabinol (THC) is the main mindaltering ingredient in the plant, which stimulates the cannabinoid receptors found on the surface of neurons, producing a psychoactive effect. Marijuana also contains some cannabinoid carboxylic acids, which, when heated during smoking, produces
Ray M. Merrill, Professor of Epidemiology and Biostatistics, Department of Health Science, College of Life Sciences, Brigham Young University, Provo, UT. Correspondence Dr Merrill; [email protected]
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panics, youth not living with their mother or father, and increased with school grade and decreased with the education of the student’s guardian. Conclusions: Those historically identified as high risk for marijuana use also were most likely to view marijuana as not harmful. Key words: adolescence, cannabis, Hispanics, marijuana, perceived risk, risk behavior, students Am J Health Behav. 2015;39(3):308-317 DOI: http://dx.doi.org/10.5993/AJHB.39.3.3
an active form of THC.5 However, the interaction effect of many of the chemical compounds in cannabis with other drugs remains largely unknown. Marijuana has been known to harbor bacteria, fungi, and pesticides, which can be harmful if inhaled. Among the chemicals in marijuana are a significant number of toxic compounds including ammonia, hydrogen cyanide, nitric oxide and certain aromatic amines.7 In addition, when marijuana is smoked, hundreds of additional chemicals are produced in the process, including carbon monoxide, cyanide, benzopyrene, and tar.8 Marijuana has been shown to result in addiction for many users, especially those who begin using the drug in their teens.9-14 Early adoption of marijuana use has been associated with an increased risk of depression in young adults whereas its heavy use also may promote anxiety.15-17 Among individuals susceptible to schizophrenia, marijuana use increases their risk of acute episodes.18 Use of marijuana also has been associated with an increased risk of psychotic disorders.19-24 Adolescents who use marijuana are at increased risk of acute cognitive impairment such as difficulties with concentration, prolonged reaction time, short-term memory deficits, increased errors in simple visual or auditory tasks, poor fine motor control and coordination, and impaired judgment, each of which is the result of attention deficit disorder.25,26 Marijuana use can produce deficits in reaction time, attention, motor performance and coordination, and information processing for up to 28 days after abstinence.27 Continued heavy use of marijuana is related to poorer complex attention functioning, poorer sequencing ability, slower psychomotor speed, and challenges
Merrill et al in verbal story memory.28 Marijuana use also can cause increased heart rate, blood pressure and, in combination with alcohol, magnified tachycardia along with impairment of cognitive, psychomotor, and driving performance.26 Withdrawal symptoms include irritability, difficulty sleeping, strange nightmares, craving, and anxiety.26 There is some evidence that marijuana use at an earlier age is more strongly related to long-term effects on cognition. One study of marijuana users who began using the substance in adolescence found that they had substantially lower connectivity among brain areas that involve learning and memory.27 A longterm study conducted in New Zealand found that individuals who began smoking marijuana heavily in their teens lost an average of 8 points in IQ between ages 13 and 38.29 The study noted that the lost cognitive abilities appeared permanent, even in those who quit smoking marijuana as adults. There was not a significant decline in IQ among those who started smoking marijuana as adults. Research has shown that even recreational marijuana use can affect brain development, altering the neural matrix of core reward structures.30 The purpose of this study was to improve understanding of which adolescents were most likely to perceive marijuana use as not harmful. METHODS Beginning in 2003, and subsequently, in alternate years, the Utah Office of Education, Department of Health, and Department of Human Services has conducted the Utah Student Health and Risk Prevention (SHARP) Survey Project.31 The SHARP Survey Project is funded by the Federal Center for Substance Abuse Prevention. Utah students are asked biennially to complete SHARP surveys, including the Prevention Needs Assessment (PNA) Survey (grades 6, 8, 10, and 12 only). The primary purpose of the information obtained from the PNA Survey was for planning important prevention and intervention programs to combat problems such as drug use and other delinquent behaviors in schools and communities. The PNA Survey was designed to assess adolescent substance use, anti-social behavior, and risk/protective factors that predict future behavioral problems among adolescents. The current study focused on 3 large school districts, comprising 53 schools in Utah County. Analyses were based on just the 2009, 2011, and 2013 PNA Surveys. Parental permission was required for the student to complete the survey and parents/guardians were assured that survey participation was voluntary, anonymous, and confidential. Approximately 2% of parents failed to provide consent and another 5% did not return the consent form. The overall participation rates during the study years were 66.3%, 65.1%, and 64.8%, respectively. The questionnaire included consistency checks. For example, a question was included on a ficti-
Am J Health Behav.™ 2015;39(3):308-317
tious drug; age was required to match their school grade, and implausible responses were considered. In the 2013 survey, 2.6% of the returned questionnaires were deemed to be unusable due to the implausibility of their answers. These questionnaires are not reflected in the current study. In 2013, survey respondents tended to have a similar sex distribution between Utah County and the entire state, with 48.2% being male in Utah County compared to 48.4% statewide.32 There was a higher percentage of Whites in Utah County (75.0% vs 72.4%) and a slightly lower percentage of other racial/ethnic groups in Utah County (eg, 12.0% vs 13.0% Hispanics). Use of marijuana (grass, pot, hash, hash oil) in the past 30 days was consistently lower in Utah County than statewide across grades (ie, 0.2 vs 0.6 in grade 6, 2.4 vs 4.2 in grade 8, 3.8 vs 9.1 in grade 10, and 5.9 vs 9.9 in grade 12). Analyses were based on survey responses from 4351 students in 2009, 6087 students in 2011, and 5713 students in 2013. A weight variable was applied to the data to make the results accurately reflect the total Utah County population of students in grades 6, 8, 10, and 12. The weighting procedure accounted for the probability of a school participating in the survey and the probability of inclusion of students in each grade and sex category in each school. Percent, mean, and risk ratio estimates were weighted. School was treated as a cluster variable in the analysis. Frequency distributions were compared between variables and assessed for significant differences using the Rao-Scott chi-square. Analyses were based on the Statistical Analysis System, version 9.4 (SAS Institute Inc., Cary, NC, USA, 2012) procedures SURVEYFREQ and SURVEYMEANS, which took school clusters and weighting into account. RESULTS The perception that marijuana use had no risk to health increased from 2009 through 2013 for students by 23% in grade 6, 64% in grade 8, 81% in grade 10, and 105% in grade 12 (Figure 1). Marijuana use also increased during this time period. For example, among students in grade 12, lifetime marijuana use increased 37%, and marijuana use in the past 30 days increased 52%. Across school grades, students who viewed marijuana use as not risky were significantly more likely to have ever used the drug or to have used it within the past 30 days (Table 1). Across school grades, students who viewed marijuana as not risky were ≥9 times more likely to have ever used marijuana. The strength of the association was even stronger between no perceived risk of marijuana use and marijuana use in the past 30 days. The perception that marijuana use has no risk significantly increased with age and school grade and decreased with the education of the student’s guardian (Table 2). Being male, non-White, Hispanic, not having a mother or father in the home,
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Use of Marijuana and Changing Risk Perceptions
Figure 1 Marijuana Risk Perception and Use
or living with a stepmother or stepfather were each a factor associated with a significant increased perception that marijuana use has no risk. In-
creased marijuana use ever or within the past 30 days followed a similar pattern. Education of the student’s guardian had the largest effect on risk
Table 1 Marijuana Use among Students According to Risk Perception of Marijuana Use
Grade 6
Marijuana Use - Ever No.
Marijuana Use - Past 30 days
Weighted No.
%
%
Risk Ratio
95% CI
%
Risk Ratio
95% CI
No Risk
139
891
10.4
2.0
9.00
2.14-37.83
1.8
Risk
1125
7646
89.6
0.2
1.00
---
0
No Risk
243
1037
12.7
21.0
9.71
6.58-14.32
23.3
23.93
11.06-51.76
Risk
1511
7116
87.3
1.8
1.00
---
1.6
1.00
---
No Risk
192
1122
14.1
37.0
9.03
6.70-12.17
19.7
14.48
9.15-22.89
Risk
1146
6830
85.9
3.8
1.00
---
1.4
1.00
---
No Risk
250
1589
20.8
51.0
9.03
6.43-12.67
23.3
15.00
8.51-26.42
Risk
885
6052
79.2
5.6
1.00
---
1.6
1.00
---
Grade 8
Grade 10
Grade 12
Data source: 2013 SHARP survey. Note. Percent and risk ratio estimates are based on weighted data.
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Table 2 Marijuana Risk Perception and Use According to Selected Demographic Variables No.
Weighted No.
%
No Risk%
Marijuana Use – Ever %
Marijuana Use Past 30 Days %
11-12
1301
8871
26.3
10.3
0.4
0.2
13-14
1859
8793
26.1
13.0
3.9
2.4
15-16
1381
8219
24.4
14.0
8.7
3.9
17-18
1172
7830
23.2
20.9
14.9
6.0
Male
2764
17219
51.1
17.2
7.7
3.5
Female
48.9
11.4
5.6
2.5
Age
Sex
2927
16459
Grade
6th
1312
8927
26.5
10.4
0.4
0.2
8th
1858
8799
26.1
12.7
4.0
2.4
10th
1371
8144
24.2
14.1
8.5
4.0
12th
23.3
20.8
14.9
5.9
1172
7844
White
Yes
4678
28335
84.0
12.4
5.4
2.4
No
1035
5378
16.0
25.2
13.3
6.5
Hispanic
Yes
799
3942
11.7
26.5
15.2
6.8
No
4914
29771
88.3
12.7
5.6
2.5
Education of Guardian
Grade school or less
71
346
1.1
25.5
19.1
9.7
Some high school
149
783
2.4
35.0
24.5
14.6
Completed high school
520
2869
8.8
26.8
14.5
6.0
Some college
802
4475
13.8
17.0
8.9
5.0
Completed college
2262
13964
43.0
10.1
4.4
1.7
Graduate or prof
1027
6459
19.9
8.8
3.6
1.4
Don’t know
624
3393
10.4
17.6
4.6
1.9
Does not apply
35
190
0.6
25.5
16.3
10.5
Yes
5383
31899
94.6
13.6
6.1
2.7
No
330
1815
5.4
27.1
17.6
7.9
Mother Lives with You
Stepmother Lives with You
Yes
204
1125
3.3
27.0
16.9
8.7
No
5509
32589
96.7
13.9
6.3
2.8
Father Lives with You
Yes
4601
27728
82.2
11.9
5.2
2.2
No
1112
5985
17.8
26.0
13.8
6.8
Stepfather Lives with You
Yes
444
2457
7.3
27.0
15.0
7.5
No
5269
31256
92.7
13.4
6.0
2.7
Data source: 2013 SHARP survey. Note. Percentages represent weighted estimates. Rao-Scott chi-square p < .0001 for the percent distribution across each variable, with the exception for marijuana in the past 30 days by sex, where p = .0205.
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Use of Marijuana and Changing Risk Perceptions
Figure 2 Perception of No Risk and Marijuana Use for Hispanics vs Non-Hispanics According to Education of Guardian
8 7
Risk Ratio (95% Confidence Interval)
6 5 4 3 2 1 0
Less than High School No Risk
High School Graduate Marijuana Use - Ever
perception and marijuana use. For example, when a guardian’s highest education was high school in comparison with other guardians who completed college, the student was 165% more likely to perceive marijuana use as not risky. They also were 230% more likely to have ever used marijuana and 253% more likely to have used marijuana in the past 30 days. Perception of no risk was similarly high when a stepmother (94% greater) or a stepfather (101% greater) was present in the home; prevalence of marijuana use was 168% greater with a stepmother and 150% greater with a stepfather in the home; and marijuana use in the past 30 days was 211% greater with a stepmother and 178% greater with a stepfather in the home. Being Hispanic was associated with 109% greater perception that marijuana was not risky. Level of education of the guardian had some influence on risk perception and use of marijuana among Hispanics compared with non-Hispanics (Figure 2). There was no significant difference in risk perception of marijuana between Hispanics
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Some College
College Graduate, Graduate, or Professional
Marijuana Use - Past 30 Days
and non-Hispanics when the guardian had less than some college. However, Hispanics had significantly greater lifetime use of marijuana in each school grade. Hispanics also were more likely to view marijuana use as not risky, to have ever used marijuana, or to have used it within the past 30 days if their guardian had some college or more education. Hispanic students were less likely to have friends who thought marijuana use was very wrong (57.4% vs 69.0%, p < .0001). The parents of Hispanic students were not significantly less likely to believe it was very wrong to use marijuana (89.2% vs 92.3%, p = .5079). Hispanic students were less likely to have their father live with them (75.4% vs 83.2%, p < .0001) and more likely to have a stepfather live with them (11.6% vs 6.7%, p < .0001). There was no significant difference whether their mother lives with them (94.5% vs 94.6%, p = .8439) or a stepmother lives with them (3.5% vs 3.3%, p = .7793). For grade 12 students only, selected academicrelated items were associated with risk-perception
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Table 3 Marijuana Risk Perception and Use According to Selected Academic Variables among Grade 12 Students No.
Weighted No.
%
No Risk %
Risk Ratio
95% CI
Marijuana Use – Ever%
Marijuana Use – Past 30 Days %
NO!
47
298
3.8
50.4
3.5
1.8-6.9
38.7
21.6
no
310
1976
25.4
30.6
2.2
1.5-3.2
23.5
9.8
yes
597
4135
53.1
16.4
1.2
0.7-2.0
11.3
4.1
YES!
206
1374
17.7
14.2
1.00
8.6
2.9
8
49
0.6
17.2
1.6
0.4-6.4
28.2
9.7
Are your grades better than most?
What were your grades like last year? Mostly F’s Mostly D’s
14
83
1.1
57.1
5.2
3.0-9.2
28.8
17.9
Mostly C’s
119
742
9.5
42.5
3.9
2.7-5.7
31.2
15.3
Mostly B’s
354
2207
28.3
32.8
3.0
2.2-4.1
25.6
9.5
Mostly A’s
669
4711
60.5
11.0
1.0
6.8
2.5
How often is school work meaningful? Never
59
379
4.9
50.9
3.9
2.3-6.6
23.6
11.3
Seldom
320
2240
28.8
24.1
1.9
1.1-3.1
21.1
8.8
Sometimes
432
2823
36.3
20.4
1.6
1.1-2.3
13.7
5.9
Often
303
2001
25.7
12.9
1.0
8.3
2.7
Almost Always
46
333
4.3
15.4
1.2
11.6
1.5
Very important
164
1016
13.0
13.4
1.0
11.0
4.4
Quite important
312
2064
26.4
18.9
1.4
0.9-2.1
11.3
6.7
Fairly important
454
3097
39.7
20.1
1.5
0.9-2.5
16.8
4.8
Slightly important
205
1415
18.1
26.2
1.9
1.1-3.6
15.7
5.9
Not at all important
30
215
2.8
48.3
3.6
2.0-6.6
35.8
23.3
0.6-2.4
Importance of school learning for later life?
How interesting are your school courses? Very interesting and stimulating
97
613
7.9
10.8
1.0
14.3
4.0
Quite interesting
367
2477
31.8
19.0
1.8
1.0-3.1
10.1
3.1
Fairly interesting
422
2787
35.8
18.9
1.7
0.9-3.4
13.1
5.4
Slightly Dull
241
1681
21.6
25.6
2.4
1.2-4.5
22.7
9.0
Very Dull
37
233
3.0
54.9
5.1
2.5-10.5
30.4
26.1
Try to do your best work in school? Never
2
9
0.1
54.5
4.2
0.8-22.2
Seldom
38
246
3.1
48.8
3.8
2.0-7.2
30.3
22.6
Sometimes
192
1201
15.4
35.9
2.8
2.1-3.7
22.5
9.2
Often
487
3345
42.8
20.4
1.6
1.0-2.5
16.5
6.0
Almost Always
449
3018
38.6
12.8
1.0
8.9
3.3
Do you enjoy being in school? Never
43
292
3.7
47.9
2.6
1.6-4.3
41.6
18.0
Seldom
154
1058
13.6
27.3
1.5
1.0-2.3
20.0
11.4
Sometimes
410
2745
35.1
18.0
1.0
0.6-1.6
13.1
4.7
Often
436
2885
36.9
19.0
1.0
0.7-1.6
12.3
4.0
Almost Always
125
830
10.6
18.5
1.0
---
14.1
Data source: 2013 SHARP survey. Note. Rao-Scott chi-square p < .0001 for the percent distribution across each variable.
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Use of Marijuana and Changing Risk Perceptions
Table 4 Marijuana Risk Perception and Use According to How Wrong it is to Use Marijuana among Grade 12 Students No.
Weighted No.
Perceived No Risk %
Risk Ratio
%
Very Wrong
803
5409
Wrong
183
1257
69.7
7.4
1.0
16.2
27.2
3.7
A Little Bit Wrong
98
Not Wrong at All
76
596
7.7
70.7
9.6
503
6.5
89.6
12.2
Very Wrong Wrong
860
5854
75.8
10.4
1.0
124
798
10.3
35.6
3.4
A Little Bit Wrong
65
390
5.1
56.1
5.4
Not Wrong at All
104
678
8.8
72.2
7.0
Marijuana Use – Ever %
Marijuana Use – Past 30 Days %
---
3.5
0.5
2.5-5.4
18.3
4.0
6.8-13.5
58.0
22.2
8.6-17.2
79.9
51.3
---
6.2
1.2
2.5-4.7
22.3
7.7
4.1-7.2
49.0
17.2
5.0-9.7
61.7
38.8
95% CI
How wrong it is to smoke marijuana?
Friends how wrong for you to use marijuana
Parent how wrong for you to use marijuana Very Wrong
1064
7124
92.0
16.7
1.0
---
11.2
3.7
Wrong
67
455
5.9
57.8
3.5
2.5-4.7
46.1
22.0
A Little Bit Wrong
15
85
1.1
100.0
95.2
66.4
Not Wrong at All
11
83
1.1
72.5
4.3
2.4-7.7
69.1
54.2
Data source: 2013 SHARP survey. Note. Rao-Scott chi-square p < .0001 for the percent distribution across each variable.
and use of marijuana (Table 3). Perception that marijuana use is not risky is significantly greater with poorer academic performance, lower effort, interest, or enjoyment in school, lower perception that school work is meaningful, or that school learning is important for later life. Marijuana use ever or in the past 30 days showed a similar pattern. A greater percent of respondents who indicated that their grades were worse than most other students were males (33.9% vs 23.8%, p < .0001), non-Whites (42.1% vs 26.5%, p < .0001), Hispanics (45.3% vs 26.8%, p < .0001), or their guardian had lower education (46.0% for grade school or less, 47.6% for some high school, 49.8% for completed high school, 31.6% for some college, 25.1% for completed college, and 19.2% for graduate or professional school, p < .0001). In addition, the percent that indicated their grades were not better than most were more likely not to live with their mother (44.6% vs 27.8%, p = .0139). They were also more likely to not live with their father (39.8% vs 26.5%, p < .0001) or to live with a stepfather (46.1% vs 27.7%, p < .0001). Grade 12 students also were asked how wrong it was for them to use marijuana, how wrong their friends thought it was to use marijuana, and how wrong their parents thought it was to use marijuana (Table 4). Risk perception of marijuana was sig-
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nificantly associated with how wrong they thought it was to use the drug. Marijuana ever use or in the past 30 days showed a similar pattern. If friends thought it was very wrong to use marijuana, 85.3% thought it was very wrong to use marijuana; if friends did not think it was very wrong to use marijuana, 20.9% thought it was very wrong to use marijuana. If parents thought it was very wrong to use marijuana, 74.6% thought it was very wrong to use marijuana, whereas if parents did not think it was very wrong to use marijuana, 15.6 thought it was very wrong to use marijuana. Those who thought it was very wrong to use marijuana were more likely to be females (75.3 vs 64.2%, p = .0070), Whites (71.1% vs 62.0%, p = .0190), or non-Hispanics (72.4% vs 49.3%, p < .0001). Their guardian also had higher education (54.3% for grade school or less, 46.8% for some high school, 63.0% for completed high school, 64.8% for some college, 75.2% for completed college, and 73.9% for graduate or professional school, p < .0001). Finally, the percent that indicated it was very wrong to use marijuana were more likely to live with their mother (71.1% vs 50.9%, p < .0001), or live with their father (73.0% vs 54.8%, p < .0001). The percent indicating it was very wrong to use marijuna was lower if they lived with a stepfather (50.5%, vs 71.1%, p = .0025).
Merrill et al DISCUSSION The increasing perception that marijuana use has no risk is consistent with state and national patterns.2,22,33 One study showed that commercialization of marijuana in Colorado has resulted in lower risk perception.34 Legalization of marijuana in many places for therapeutic purposes also may have contributed to lower perception of marijuana risk.35,36 On the other hand, one study found that legalization was not related to perceived risk of monthly use of marijuana.37 A direct relationship was observed within each school grade of decreasing risk perception of marijuana use and increasing use of the drug. This observation is consistent with other studies.2,38-40 Across school grades, students who viewed marijuana as not risky were ≥9 times more likely to have ever used marijuana. The strength of the association was even stronger between no perceived risk of marijuana use and marijuana use in the past 30 days, indicating a dose-response relationship. Adolescence is a key risk period for drug abuse because it involves major transitional periods, such as new and demanding academic, social, and emotional challenges associated with school.41 In high school, students have the additional challenge of anticipating leaving home for college or work, which can heighten stress and, consequently, increase experimentation and reliance on drugs. It may be that some of the decreasing risk perception seen in late teen years is an attempt to justify use of marijuana as life’s challenges become greater. The Theory of Health Behavior indicates that health behaviors are directly influenced by anticipated benefits versus the costs of the action.42,43 In a study of 15 commonly used drugs, regular users rated the drugs’ potential harms and benefits. The study involved 5791 individuals from over 40 countries.44 Of several potential harms and benefits presented to the participants, marijuana was ranked consistently more beneficial and less harmful than the other psychoactive drugs, which helps explain why it is the most commonly used psychoactive drug in the world. The World Health Organization estimates that about 147 million people (2.5% of the world’s population), consumes cannabis, compared with 0.2% who use cocaine and 0.2% who use opiates.45 This study found that those who were more likely to view marijuana use as not risky were also more likely to perform poorer academically, to come from families where the guardian had lower education, not to live with a mother or father or to live with a stepfather, or to be a member of a racial/ethnic minority group. These were also the individuals most likely to use marijuana. Other research has shown these characteristics to be most commonly associated with marijuana use.46 High risk groups for marijuana use may perceive less risk from the behavior because they are not educated by their guardians about marijuana risks,
parental support and supervision may be absent, or poor engagement in school may cause them to miss drug prevention messages. Further, if those using marijuana do not value the importance of school learning for later life, although they may recognize that marijuana use can hurt their academic performance, this may not matter to them and, therefore, they would not view marijuana as a risky behavior. This may be increasingly true in families where the guardian has lower education, potentially resulting in education being less valued. Marijuana use is associated with poorer academic performance.47,48 Data from 3 large, long-running longitudinal studies in Australia and New Zealand, shows dose-response relationships between cannabis use and reduction in high-school completion and degree attainment, increased later cannabis dependence, use of other illicit drugs, and suicide attempts.48 In addition, early onset of marijuana use is related to lower educational attainment.49-51 Parent and peer perception of how wrong marijuana use is strongly correlated with the student’s perception of how wrong it is. Marijuana use is greater among those whose parents and/or peers use marijuana.46 There is a stronger correlation between peer perception of how wrong it is to use marijuana and how wrong the student perceives it to be than between the parents’ perception of how wrong it is compared with the students. The greater influence from friends may result if parents are not present to monitor and provide structure in their child’s life. The current study found that students were less likely to view marijuana use as very wrong if they did not live with their mother or father, or lived with a stepfather. Such situations often are associated with poor and inconsistent family management practices, more family conflict, low bonding, poor parental monitoring, and lack of structure and rules, each being a risk factor for marijuana use.52 Peer influence toward marijuana use has the potential to play an even bigger role in the student’s life in such situations. Hispanic students were less likely to perceive marijuana use as risky and more likely to have ever used marijuana or to have used it within the past 30 days. Although Hispanic parents were not less likely than their non-Hispanic counterparts to view marijuana use as very wrong, their friends were significantly less likely to view marijuana use as very wrong. The fact that Hispanic students tended to view education as less important for later life and have poorer academic performance than non-Hispanic students supports why they may be more likely to perceive marijuana as not risky. In addition, because Hispanic students are less likely to live with their father or more likely to live with a stepfather, there may be less family monitoring, which, in turn, may cause Hispanic students to be more likely to be influenced by peers.53 The higher consumption of marijuana among Hispanics
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Use of Marijuana and Changing Risk Perceptions compared with non-Hispanics (who are primarily Whites in our survey) is consistent with the National Survey on Drug Use and Health for adolescents.54 Conclusion The association between perceived risk and use of marijuana is complex. Some of the decrease in perceived risk may be because of legalization of marijuana for medical and recreational uses. Although the literature provides considerable evidence that marijuana use can have detrimental effects in terms of academic performance, low connectedness to school, truancy, and school dropout, if these areas are not valued as important, then marijuana may not be considered by the student to be risky behavior. Furthermore, challenging life changes through adolescence may cause many to adopt marijuana as a means of coping, with the perceived benefits outweighing perceived harm. This is especially true for students raised in households where education is less valued, and where there is less family monitoring and family structure, thereby leaving them more open to the influence of substance-using peers. Human Subjects Statement This secondary data analysis was deemed exempt from human subjects review. Conflict of Interest Statement None to declare. References
1. The Science of Drug Abuse & Addiction. Drug Facts: Marijuana. National Institute on Drug Abuse (on-line). Available at: http://www.drugabuse.gov/publications/ drugfacts/marijuana. Revised January 2014. Accessed October 31, 2014. 2. The Science of Drug Abuse & Addiction. Monitoring the Future Survey, Overview of Findings 2013. National Institute on Drug Abuse (on-line). Available at: http:// www.drugabuse.gov/monitoring-future-survey-over view-findings-2013. Revised December 2013. Accessed October 31, 2014. 3. The Science of Drug Abuse & Addiction. Drug Facts: High School and Youth Trends. National Institute on Drug Abuse (on-line). Available at: http://www.drugabuse. gov/publications/drugfacts/high-school-youth-trends. Revised January 2014. Accessed October 31, 2014. 4. Joffe A, American Academy of Pediatrics Committee on Substance Abuse, American Academy of Pediatrics Committee on Adolescence. Legalization of marijuana: potential impact on youth. Pediatrics. 2004;113(6):1825-1826. 5. Maldonado R, Berrendero F, Ozaita A, Robledo P. Neurochemical basis of cannabis addiction. Neuroscience. 2011;181:1-17. 6. Elsohly MA, Slade D. Chemical constituents of marijuana: the complex mixture of natural cannabinoids. Life Sciences. 2005;78(5):539-548. 7. American Chemical Society. Marijuana Smoke Contains Higher Levels Of Certain Toxins Than Tobacco Smoke. ScienceDaily (on-line). Available at: http://www.sciencedaily.com/releases/2007/12/071217110328.htm. Published December 18, 2007. Accessed October 31, 2014. 8. Buha A. Marijuana. Toxipedia (on-line). Available at:
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http://www.toxipedia.org/display/toxipedia/Marijuana. Updated August 3, 2011. Accessed October 31, 2014. 9. Anthony JC, Warner LA, Kessler RC. Comparative epidemiology of dependence on tobacco, alcohol, controlled substances, and inhalants: basic findings from the national comorbidity survey. Exp Clin Psychopharmacol. 2004;2(3):244-268. 10. Chen CY, O’Brien MS, Anthony JC. Who becomes cannabis dependent soon after onset of use? Epidemiological evidence from the United States: 2000-2001. Drug Alcohol Depend. 2005; 79(1):11-22. 11. Kokkevi A, Gabhainn SN, Spyropoulou M. Early initiation of cannabis use: a cross national European perspective. J Adolesc Health. 2006;39:712-719. 12. Compton WM, Grant BF, Colliver JD, et al. Prevalence of cannabis use disorders in the U.S.: 1991-1992 and 2001-2002. JAMA. 2004;291:2114-2121. 13. SAMHSA, Office of Applied studies. Treatment episode data set (teds): 2009 discharges from substance abuse treatment services. DASIS. 2009. 14. Hurd YL, Michaelides M, Miller ML, Jutras-Aswad D. Trajectory of adolescent cannabis use on addiction vulnerability. Neuropharmacology. 2014;76(Pt B):416-424. 15. Hayatbakhsh MR, Najman JM, Jamrozik K, et al. Cannabis and anxiety and depression in young adults: a large prospective study. J Am Acad Child Adolesc Psychiatry. 2007;46(3):408-417. 16. Somaini L, Manfredini M, Amore M, et al. Psychological responses to unpleasant emotions in cannabis users. Eur Arch Psychiatry Clin Neurosci. 2012;262(1):47-57. 17. Degenhardt L, Coffey C, Romaniuk H, et al. The persistence of the association between adolescent cannabis use and common mental disorders into young adulthood. Addiction. 2013;108:124-133. 18. Hall W, Degenhardt L. Prevalence and correlates of cannabis use in developed and developing countries. Curr Opin Psychiatry. 2007;20:393-397. 19. Grech A, Van Os J, Jones PB, et al. Cannabis use and outcome of recent onset psychosis. Eur Psychiatry. 2005;20:349-353. 20. Large M, Sharma S, Compton MT, et al. Cannabis use and earlier onset of psychosis: a systematic meta-analysis. Arch Gen Psychiatry. 2011;68(6):555-561. 21. Sharma P, Murthy P, Bharath MM. Chemistry, metabolism, and toxicology of cannabis: clinical implications. Iran J Psychiatry. 2012;7(4):149-156. 22. Shapiro GK, Buckley-Hunter L. What every adolescent needs to know: cannabis can cause psychosis. J Psychosom Res. 2010;69(6):533-539. 23. Le Bec PY, Fatséas M, Denis C, et al. Cannabis and psychosis: search of a causal link through a critical and systematic review. Encephale. 2009;35(4):377-385. 24. Dragt S, Nieman DH, Schultze-Lutter F, et al. Cannabis use and age at onset of symptoms in subjects at clinical high risk for psychosis. Acta Psychiatr Scand. 2012;125(1):45-53. 25. Leweke M, Kampmann C, Radwan M, et al. The effects of tetrahydrocannibol on the recognition of emotionally charged words: an analysis using event-related brain potentials. Neuropsycholobiology. 1998;37:104-111. 26. The Science of Drug Abuse & Addiction. Health Effects. National Institute on Drug Abuse (on-line). Available at: http://www.drugabuse.gov/drugs-abuse/commonlyabused-drugs/health-effects#marijuana. Accessed October 31, 2014. 27. Hall W, Degenhardt L. Adverse health effects of nonmedical use of cannabis. Lancet. 2009;374:1383-1391. 28. Schweinsburg AD, Brown SA, Tapert SF. The influence of cannabis on neurocognitive functioning in adolescents. Curr Drug Abuse Rev. 2008;1(1):99-111. 29. Meier MH, Caspi A, Ambler A, et al. Persistent cannabis
Merrill et al users show neuropsychological decline from childhood to midlife. Proc Natl Acad Sci USA. 2012;109(40):E2657E2664. 30. Gilman JM, Kuster JK, Lee S, et al. Cannabis use is quantitatively associated with nucleus accumbens and amygdala abnormalities in young adult recreational users. J Neurosci. 2014;34(16):5529-5538. 31. Substance Abuse & Mental Health. SHARP Survey Reports. State of Utah Department of Human Services Division of Substance Abuse and Mental Health (on-line). Available at: http://dsamh.utah.gov/data/sharp-survey-reports/. Accessed October 31, 2014. 32. Student Health and Risk Prevention. 2013 Prevention Needs Assessment Survey Revised Results. State of Utah Department of Human Services Division of Substance Abuse and Mental Health (on-line). Available at: http:// dsamh.utah.gov/pdf/sharp/2013/Utah%20County%20 LSAA%20Profile%20Report.pdf. Revised January, 2014. Accessed September 11, 2014. 33. Boulder County High School Student Youth Risk Behavior Survey Results. Boulder County Public Health. Marijuana Use and Perceptions among Boulder Couth Youth (on-line). Available at: http://www.bouldercounty.org/ doc/publichealth/mjyrbsdata.pdf. Accessed November 1, 2014. 34. Schuermeyer J, Salomonsen-Sautel S, Price RK, et al. Temporal trends in marijuana attitudes, availability and use in Colorado compared to non-medical marijuana states: 2003-11. Drug Alcohol Depend. 2014;55140:51455155. 35. Wall MM, Poh E, Cerda M, et al. Adolescent marijuana use from 2002 to 2008: higher in states with medical marijuana laws, cause still unclear. Ann Epidemiol. 2011;21(9):714-716. 36. Schuermeyer J, Salomonsen-Sautel S, Price RK, et al. Temporal trends in marijuana attitudes, availability and use in Colorado compared to non-medical marijuana states: 2003–2011. Drug Alcohol Depend. 2014;140:145155. 37. Harper S, Strumpf EC, Kaufman JS. Do medical marijuana laws increase marijuana use? Replication study and extension. Ann Epidemiol. 2012;22(3):207-212. 38. Lopez-Quintero C, Neumark Y. Effects of risk perception of marijuana use on marijuana use and intentions to use among adolescents in Bogotá, Colombia. Drug Alcohol Depend. 2010;109(1-3):65-72. 39. Thornton LK, Baker AL, Johnson MP, Lewin T. Perceived risk associated with tobacco, alcohol and cannabis use among people with and without psychotic disorders. Addict Behav. 2013;38(6):2246-2251. 40. Kilmer JR, Hunt SB, Lee CM, Neighbors C. Marijuana use, risk perception, and consequences: is perceived risk
congruent with reality? Addict Behav. 2007;32(12):30263033. 41. The Science of Drug Abuse & Addiction. Preventing Drug Use among Children and Adolescents (In Brief). National Institute on Drug Abuse (on-line). Available at: http:// www.drugabuse.gov/publications/preventing-drugabuse-among-children-adolescents/chapter-1-risk-factors-protective-factors/what-are-highest-risk.Updated October 2003. Accessed September 18, 2014. 42. Prochaska JO, DiClemente CC. Stages of change in the modification of problem behaviors. Prog Behav Modif. 1992;28:184-218. 43. Glanz K, Marcus Lewis F, Rimer BK. Theory at a Glance: A Guide for Health Promotion Practice. Bethesda, MD: National Institutes of Health; 1997. 44. Morgan CJ, Noronha LA, Muetzelfeldt M, et al. Harms and benefits associated with psychoactive drugs: findings of an international survey of active drug users. J Psychopharmacol. 2013;27(6):497-506. 45. Cannabis. Management of Substance Abuse. World Health Organization Web site. Available at: http://www. who.int/substance_abuse/facts/cannabis/en/. Accessed October 23, 2014. 46. Wills TA, Vaccaro D, McNamara G, Hirky AE. Escalated substance use: a longitudinal grouping analysis from early to middle adolescence. J Abnorm Psychol. 1996;105(2):166-180. 47. van den Bree MBM, Pickworth WB. Risk factors predicting changes in marijuana involvement in teenagers. Arch Gen Psychiatry. 2005;62(3):311-319. 48. Silins E, Horwood LJ, Patton GC, et al. Young adult sequelae of adolescent cannabis use: an integrative analysis. Lancet Psychiatry. 2014;1(4):286-293. 49. Verweij KJ, Huizink AC, Agrawal A, et al. Is the relationship between early-onset cannabis use and educational attainment causal or due to common liability? Drug Alcohol Depend. 2013;133(2):580-586. 50. Fergusson DM, Boden JM. Cannabis use and later life outcomes. Addiction. 2008;103(6):969-978. 51. Lynskey M, Hall W. The effects of adolescent cannabis use on educational attainment: a review. Addiction. 2000;95(11):1621-1630. 52. Van den Bree MM, Pickworth WB. Risk factors predicting changes in marijuana involvement in teenagers. Arc Gen Psychiatry. 2005;62(3):311-319. 53. Chilcoat HD, Anthony JC. Impact of parent monitoring on initiation of drug use through late childhood. J Am Acad Child Adolesc Psychiatry. 1996;35(1):91-100. 54. Wu LT, Brady KT, Mannelli P, et al. Cannabis use disorders are comparatively prevalent among nonwhite racial/ethnic groups and adolescents: a national study. J Psychiatr Res. 2014;50:26-35.
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M
arijuana (the dried leaves, flowers, stems, and seeds from the hemp plant Cannabis sativa) is the most commonly used illicit drug in the United States.1 In 2013, 22.7% of high school seniors used marijuana in the past 30 days, representing an increase of 3.3% from 2008.2 An increase in marijuana use also was observed in earlier school grades. This increase paralleled decreasing perceived risk of harm associated with marijuana use.2 The changing perception of risk is likely supported by legalization of medical marijuana in 23 states and the District of Columbia, and legalization of recreational marijuana use in 4 states and the District of Columbia in the US as well as in other countries throughout the world.1,3,4 Softening risk perceptions of marijuana use is expanding despite the fact that there remains much that we do not know about the health effects of the drug. At least 489 chemical compounds, with 70 unique to the cannabis plant, have been identified in marijuana.5 Cannabis is chemically complex due to the vast number of its constituents and their possible interaction with one another.6 We do know that tetrahydrocannabinol (THC) is the main mindaltering ingredient in the plant, which stimulates the cannabinoid receptors found on the surface of neurons, producing a psychoactive effect. Marijuana also contains some cannabinoid carboxylic acids, which, when heated during smoking, produces
Ray M. Merrill, Professor of Epidemiology and Biostatistics, Department of Health Science, College of Life Sciences, Brigham Young University, Provo, UT. Correspondence Dr Merrill; [email protected]
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panics, youth not living with their mother or father, and increased with school grade and decreased with the education of the student’s guardian. Conclusions: Those historically identified as high risk for marijuana use also were most likely to view marijuana as not harmful. Key words: adolescence, cannabis, Hispanics, marijuana, perceived risk, risk behavior, students Am J Health Behav. 2015;39(3):308-317 DOI: http://dx.doi.org/10.5993/AJHB.39.3.3
an active form of THC.5 However, the interaction effect of many of the chemical compounds in cannabis with other drugs remains largely unknown. Marijuana has been known to harbor bacteria, fungi, and pesticides, which can be harmful if inhaled. Among the chemicals in marijuana are a significant number of toxic compounds including ammonia, hydrogen cyanide, nitric oxide and certain aromatic amines.7 In addition, when marijuana is smoked, hundreds of additional chemicals are produced in the process, including carbon monoxide, cyanide, benzopyrene, and tar.8 Marijuana has been shown to result in addiction for many users, especially those who begin using the drug in their teens.9-14 Early adoption of marijuana use has been associated with an increased risk of depression in young adults whereas its heavy use also may promote anxiety.15-17 Among individuals susceptible to schizophrenia, marijuana use increases their risk of acute episodes.18 Use of marijuana also has been associated with an increased risk of psychotic disorders.19-24 Adolescents who use marijuana are at increased risk of acute cognitive impairment such as difficulties with concentration, prolonged reaction time, short-term memory deficits, increased errors in simple visual or auditory tasks, poor fine motor control and coordination, and impaired judgment, each of which is the result of attention deficit disorder.25,26 Marijuana use can produce deficits in reaction time, attention, motor performance and coordination, and information processing for up to 28 days after abstinence.27 Continued heavy use of marijuana is related to poorer complex attention functioning, poorer sequencing ability, slower psychomotor speed, and challenges
Merrill et al in verbal story memory.28 Marijuana use also can cause increased heart rate, blood pressure and, in combination with alcohol, magnified tachycardia along with impairment of cognitive, psychomotor, and driving performance.26 Withdrawal symptoms include irritability, difficulty sleeping, strange nightmares, craving, and anxiety.26 There is some evidence that marijuana use at an earlier age is more strongly related to long-term effects on cognition. One study of marijuana users who began using the substance in adolescence found that they had substantially lower connectivity among brain areas that involve learning and memory.27 A longterm study conducted in New Zealand found that individuals who began smoking marijuana heavily in their teens lost an average of 8 points in IQ between ages 13 and 38.29 The study noted that the lost cognitive abilities appeared permanent, even in those who quit smoking marijuana as adults. There was not a significant decline in IQ among those who started smoking marijuana as adults. Research has shown that even recreational marijuana use can affect brain development, altering the neural matrix of core reward structures.30 The purpose of this study was to improve understanding of which adolescents were most likely to perceive marijuana use as not harmful. METHODS Beginning in 2003, and subsequently, in alternate years, the Utah Office of Education, Department of Health, and Department of Human Services has conducted the Utah Student Health and Risk Prevention (SHARP) Survey Project.31 The SHARP Survey Project is funded by the Federal Center for Substance Abuse Prevention. Utah students are asked biennially to complete SHARP surveys, including the Prevention Needs Assessment (PNA) Survey (grades 6, 8, 10, and 12 only). The primary purpose of the information obtained from the PNA Survey was for planning important prevention and intervention programs to combat problems such as drug use and other delinquent behaviors in schools and communities. The PNA Survey was designed to assess adolescent substance use, anti-social behavior, and risk/protective factors that predict future behavioral problems among adolescents. The current study focused on 3 large school districts, comprising 53 schools in Utah County. Analyses were based on just the 2009, 2011, and 2013 PNA Surveys. Parental permission was required for the student to complete the survey and parents/guardians were assured that survey participation was voluntary, anonymous, and confidential. Approximately 2% of parents failed to provide consent and another 5% did not return the consent form. The overall participation rates during the study years were 66.3%, 65.1%, and 64.8%, respectively. The questionnaire included consistency checks. For example, a question was included on a ficti-
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tious drug; age was required to match their school grade, and implausible responses were considered. In the 2013 survey, 2.6% of the returned questionnaires were deemed to be unusable due to the implausibility of their answers. These questionnaires are not reflected in the current study. In 2013, survey respondents tended to have a similar sex distribution between Utah County and the entire state, with 48.2% being male in Utah County compared to 48.4% statewide.32 There was a higher percentage of Whites in Utah County (75.0% vs 72.4%) and a slightly lower percentage of other racial/ethnic groups in Utah County (eg, 12.0% vs 13.0% Hispanics). Use of marijuana (grass, pot, hash, hash oil) in the past 30 days was consistently lower in Utah County than statewide across grades (ie, 0.2 vs 0.6 in grade 6, 2.4 vs 4.2 in grade 8, 3.8 vs 9.1 in grade 10, and 5.9 vs 9.9 in grade 12). Analyses were based on survey responses from 4351 students in 2009, 6087 students in 2011, and 5713 students in 2013. A weight variable was applied to the data to make the results accurately reflect the total Utah County population of students in grades 6, 8, 10, and 12. The weighting procedure accounted for the probability of a school participating in the survey and the probability of inclusion of students in each grade and sex category in each school. Percent, mean, and risk ratio estimates were weighted. School was treated as a cluster variable in the analysis. Frequency distributions were compared between variables and assessed for significant differences using the Rao-Scott chi-square. Analyses were based on the Statistical Analysis System, version 9.4 (SAS Institute Inc., Cary, NC, USA, 2012) procedures SURVEYFREQ and SURVEYMEANS, which took school clusters and weighting into account. RESULTS The perception that marijuana use had no risk to health increased from 2009 through 2013 for students by 23% in grade 6, 64% in grade 8, 81% in grade 10, and 105% in grade 12 (Figure 1). Marijuana use also increased during this time period. For example, among students in grade 12, lifetime marijuana use increased 37%, and marijuana use in the past 30 days increased 52%. Across school grades, students who viewed marijuana use as not risky were significantly more likely to have ever used the drug or to have used it within the past 30 days (Table 1). Across school grades, students who viewed marijuana as not risky were ≥9 times more likely to have ever used marijuana. The strength of the association was even stronger between no perceived risk of marijuana use and marijuana use in the past 30 days. The perception that marijuana use has no risk significantly increased with age and school grade and decreased with the education of the student’s guardian (Table 2). Being male, non-White, Hispanic, not having a mother or father in the home,
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Use of Marijuana and Changing Risk Perceptions
Figure 1 Marijuana Risk Perception and Use
or living with a stepmother or stepfather were each a factor associated with a significant increased perception that marijuana use has no risk. In-
creased marijuana use ever or within the past 30 days followed a similar pattern. Education of the student’s guardian had the largest effect on risk
Table 1 Marijuana Use among Students According to Risk Perception of Marijuana Use
Grade 6
Marijuana Use - Ever No.
Marijuana Use - Past 30 days
Weighted No.
%
%
Risk Ratio
95% CI
%
Risk Ratio
95% CI
No Risk
139
891
10.4
2.0
9.00
2.14-37.83
1.8
Risk
1125
7646
89.6
0.2
1.00
---
0
No Risk
243
1037
12.7
21.0
9.71
6.58-14.32
23.3
23.93
11.06-51.76
Risk
1511
7116
87.3
1.8
1.00
---
1.6
1.00
---
No Risk
192
1122
14.1
37.0
9.03
6.70-12.17
19.7
14.48
9.15-22.89
Risk
1146
6830
85.9
3.8
1.00
---
1.4
1.00
---
No Risk
250
1589
20.8
51.0
9.03
6.43-12.67
23.3
15.00
8.51-26.42
Risk
885
6052
79.2
5.6
1.00
---
1.6
1.00
---
Grade 8
Grade 10
Grade 12
Data source: 2013 SHARP survey. Note. Percent and risk ratio estimates are based on weighted data.
310
Merrill et al
Table 2 Marijuana Risk Perception and Use According to Selected Demographic Variables No.
Weighted No.
%
No Risk%
Marijuana Use – Ever %
Marijuana Use Past 30 Days %
11-12
1301
8871
26.3
10.3
0.4
0.2
13-14
1859
8793
26.1
13.0
3.9
2.4
15-16
1381
8219
24.4
14.0
8.7
3.9
17-18
1172
7830
23.2
20.9
14.9
6.0
Male
2764
17219
51.1
17.2
7.7
3.5
Female
48.9
11.4
5.6
2.5
Age
Sex
2927
16459
Grade
6th
1312
8927
26.5
10.4
0.4
0.2
8th
1858
8799
26.1
12.7
4.0
2.4
10th
1371
8144
24.2
14.1
8.5
4.0
12th
23.3
20.8
14.9
5.9
1172
7844
White
Yes
4678
28335
84.0
12.4
5.4
2.4
No
1035
5378
16.0
25.2
13.3
6.5
Hispanic
Yes
799
3942
11.7
26.5
15.2
6.8
No
4914
29771
88.3
12.7
5.6
2.5
Education of Guardian
Grade school or less
71
346
1.1
25.5
19.1
9.7
Some high school
149
783
2.4
35.0
24.5
14.6
Completed high school
520
2869
8.8
26.8
14.5
6.0
Some college
802
4475
13.8
17.0
8.9
5.0
Completed college
2262
13964
43.0
10.1
4.4
1.7
Graduate or prof
1027
6459
19.9
8.8
3.6
1.4
Don’t know
624
3393
10.4
17.6
4.6
1.9
Does not apply
35
190
0.6
25.5
16.3
10.5
Yes
5383
31899
94.6
13.6
6.1
2.7
No
330
1815
5.4
27.1
17.6
7.9
Mother Lives with You
Stepmother Lives with You
Yes
204
1125
3.3
27.0
16.9
8.7
No
5509
32589
96.7
13.9
6.3
2.8
Father Lives with You
Yes
4601
27728
82.2
11.9
5.2
2.2
No
1112
5985
17.8
26.0
13.8
6.8
Stepfather Lives with You
Yes
444
2457
7.3
27.0
15.0
7.5
No
5269
31256
92.7
13.4
6.0
2.7
Data source: 2013 SHARP survey. Note. Percentages represent weighted estimates. Rao-Scott chi-square p < .0001 for the percent distribution across each variable, with the exception for marijuana in the past 30 days by sex, where p = .0205.
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Use of Marijuana and Changing Risk Perceptions
Figure 2 Perception of No Risk and Marijuana Use for Hispanics vs Non-Hispanics According to Education of Guardian
8 7
Risk Ratio (95% Confidence Interval)
6 5 4 3 2 1 0
Less than High School No Risk
High School Graduate Marijuana Use - Ever
perception and marijuana use. For example, when a guardian’s highest education was high school in comparison with other guardians who completed college, the student was 165% more likely to perceive marijuana use as not risky. They also were 230% more likely to have ever used marijuana and 253% more likely to have used marijuana in the past 30 days. Perception of no risk was similarly high when a stepmother (94% greater) or a stepfather (101% greater) was present in the home; prevalence of marijuana use was 168% greater with a stepmother and 150% greater with a stepfather in the home; and marijuana use in the past 30 days was 211% greater with a stepmother and 178% greater with a stepfather in the home. Being Hispanic was associated with 109% greater perception that marijuana was not risky. Level of education of the guardian had some influence on risk perception and use of marijuana among Hispanics compared with non-Hispanics (Figure 2). There was no significant difference in risk perception of marijuana between Hispanics
312
Some College
College Graduate, Graduate, or Professional
Marijuana Use - Past 30 Days
and non-Hispanics when the guardian had less than some college. However, Hispanics had significantly greater lifetime use of marijuana in each school grade. Hispanics also were more likely to view marijuana use as not risky, to have ever used marijuana, or to have used it within the past 30 days if their guardian had some college or more education. Hispanic students were less likely to have friends who thought marijuana use was very wrong (57.4% vs 69.0%, p < .0001). The parents of Hispanic students were not significantly less likely to believe it was very wrong to use marijuana (89.2% vs 92.3%, p = .5079). Hispanic students were less likely to have their father live with them (75.4% vs 83.2%, p < .0001) and more likely to have a stepfather live with them (11.6% vs 6.7%, p < .0001). There was no significant difference whether their mother lives with them (94.5% vs 94.6%, p = .8439) or a stepmother lives with them (3.5% vs 3.3%, p = .7793). For grade 12 students only, selected academicrelated items were associated with risk-perception
Merrill et al
Table 3 Marijuana Risk Perception and Use According to Selected Academic Variables among Grade 12 Students No.
Weighted No.
%
No Risk %
Risk Ratio
95% CI
Marijuana Use – Ever%
Marijuana Use – Past 30 Days %
NO!
47
298
3.8
50.4
3.5
1.8-6.9
38.7
21.6
no
310
1976
25.4
30.6
2.2
1.5-3.2
23.5
9.8
yes
597
4135
53.1
16.4
1.2
0.7-2.0
11.3
4.1
YES!
206
1374
17.7
14.2
1.00
8.6
2.9
8
49
0.6
17.2
1.6
0.4-6.4
28.2
9.7
Are your grades better than most?
What were your grades like last year? Mostly F’s Mostly D’s
14
83
1.1
57.1
5.2
3.0-9.2
28.8
17.9
Mostly C’s
119
742
9.5
42.5
3.9
2.7-5.7
31.2
15.3
Mostly B’s
354
2207
28.3
32.8
3.0
2.2-4.1
25.6
9.5
Mostly A’s
669
4711
60.5
11.0
1.0
6.8
2.5
How often is school work meaningful? Never
59
379
4.9
50.9
3.9
2.3-6.6
23.6
11.3
Seldom
320
2240
28.8
24.1
1.9
1.1-3.1
21.1
8.8
Sometimes
432
2823
36.3
20.4
1.6
1.1-2.3
13.7
5.9
Often
303
2001
25.7
12.9
1.0
8.3
2.7
Almost Always
46
333
4.3
15.4
1.2
11.6
1.5
Very important
164
1016
13.0
13.4
1.0
11.0
4.4
Quite important
312
2064
26.4
18.9
1.4
0.9-2.1
11.3
6.7
Fairly important
454
3097
39.7
20.1
1.5
0.9-2.5
16.8
4.8
Slightly important
205
1415
18.1
26.2
1.9
1.1-3.6
15.7
5.9
Not at all important
30
215
2.8
48.3
3.6
2.0-6.6
35.8
23.3
0.6-2.4
Importance of school learning for later life?
How interesting are your school courses? Very interesting and stimulating
97
613
7.9
10.8
1.0
14.3
4.0
Quite interesting
367
2477
31.8
19.0
1.8
1.0-3.1
10.1
3.1
Fairly interesting
422
2787
35.8
18.9
1.7
0.9-3.4
13.1
5.4
Slightly Dull
241
1681
21.6
25.6
2.4
1.2-4.5
22.7
9.0
Very Dull
37
233
3.0
54.9
5.1
2.5-10.5
30.4
26.1
Try to do your best work in school? Never
2
9
0.1
54.5
4.2
0.8-22.2
Seldom
38
246
3.1
48.8
3.8
2.0-7.2
30.3
22.6
Sometimes
192
1201
15.4
35.9
2.8
2.1-3.7
22.5
9.2
Often
487
3345
42.8
20.4
1.6
1.0-2.5
16.5
6.0
Almost Always
449
3018
38.6
12.8
1.0
8.9
3.3
Do you enjoy being in school? Never
43
292
3.7
47.9
2.6
1.6-4.3
41.6
18.0
Seldom
154
1058
13.6
27.3
1.5
1.0-2.3
20.0
11.4
Sometimes
410
2745
35.1
18.0
1.0
0.6-1.6
13.1
4.7
Often
436
2885
36.9
19.0
1.0
0.7-1.6
12.3
4.0
Almost Always
125
830
10.6
18.5
1.0
---
14.1
Data source: 2013 SHARP survey. Note. Rao-Scott chi-square p < .0001 for the percent distribution across each variable.
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Use of Marijuana and Changing Risk Perceptions
Table 4 Marijuana Risk Perception and Use According to How Wrong it is to Use Marijuana among Grade 12 Students No.
Weighted No.
Perceived No Risk %
Risk Ratio
%
Very Wrong
803
5409
Wrong
183
1257
69.7
7.4
1.0
16.2
27.2
3.7
A Little Bit Wrong
98
Not Wrong at All
76
596
7.7
70.7
9.6
503
6.5
89.6
12.2
Very Wrong Wrong
860
5854
75.8
10.4
1.0
124
798
10.3
35.6
3.4
A Little Bit Wrong
65
390
5.1
56.1
5.4
Not Wrong at All
104
678
8.8
72.2
7.0
Marijuana Use – Ever %
Marijuana Use – Past 30 Days %
---
3.5
0.5
2.5-5.4
18.3
4.0
6.8-13.5
58.0
22.2
8.6-17.2
79.9
51.3
---
6.2
1.2
2.5-4.7
22.3
7.7
4.1-7.2
49.0
17.2
5.0-9.7
61.7
38.8
95% CI
How wrong it is to smoke marijuana?
Friends how wrong for you to use marijuana
Parent how wrong for you to use marijuana Very Wrong
1064
7124
92.0
16.7
1.0
---
11.2
3.7
Wrong
67
455
5.9
57.8
3.5
2.5-4.7
46.1
22.0
A Little Bit Wrong
15
85
1.1
100.0
95.2
66.4
Not Wrong at All
11
83
1.1
72.5
4.3
2.4-7.7
69.1
54.2
Data source: 2013 SHARP survey. Note. Rao-Scott chi-square p < .0001 for the percent distribution across each variable.
and use of marijuana (Table 3). Perception that marijuana use is not risky is significantly greater with poorer academic performance, lower effort, interest, or enjoyment in school, lower perception that school work is meaningful, or that school learning is important for later life. Marijuana use ever or in the past 30 days showed a similar pattern. A greater percent of respondents who indicated that their grades were worse than most other students were males (33.9% vs 23.8%, p < .0001), non-Whites (42.1% vs 26.5%, p < .0001), Hispanics (45.3% vs 26.8%, p < .0001), or their guardian had lower education (46.0% for grade school or less, 47.6% for some high school, 49.8% for completed high school, 31.6% for some college, 25.1% for completed college, and 19.2% for graduate or professional school, p < .0001). In addition, the percent that indicated their grades were not better than most were more likely not to live with their mother (44.6% vs 27.8%, p = .0139). They were also more likely to not live with their father (39.8% vs 26.5%, p < .0001) or to live with a stepfather (46.1% vs 27.7%, p < .0001). Grade 12 students also were asked how wrong it was for them to use marijuana, how wrong their friends thought it was to use marijuana, and how wrong their parents thought it was to use marijuana (Table 4). Risk perception of marijuana was sig-
314
nificantly associated with how wrong they thought it was to use the drug. Marijuana ever use or in the past 30 days showed a similar pattern. If friends thought it was very wrong to use marijuana, 85.3% thought it was very wrong to use marijuana; if friends did not think it was very wrong to use marijuana, 20.9% thought it was very wrong to use marijuana. If parents thought it was very wrong to use marijuana, 74.6% thought it was very wrong to use marijuana, whereas if parents did not think it was very wrong to use marijuana, 15.6 thought it was very wrong to use marijuana. Those who thought it was very wrong to use marijuana were more likely to be females (75.3 vs 64.2%, p = .0070), Whites (71.1% vs 62.0%, p = .0190), or non-Hispanics (72.4% vs 49.3%, p < .0001). Their guardian also had higher education (54.3% for grade school or less, 46.8% for some high school, 63.0% for completed high school, 64.8% for some college, 75.2% for completed college, and 73.9% for graduate or professional school, p < .0001). Finally, the percent that indicated it was very wrong to use marijuana were more likely to live with their mother (71.1% vs 50.9%, p < .0001), or live with their father (73.0% vs 54.8%, p < .0001). The percent indicating it was very wrong to use marijuna was lower if they lived with a stepfather (50.5%, vs 71.1%, p = .0025).
Merrill et al DISCUSSION The increasing perception that marijuana use has no risk is consistent with state and national patterns.2,22,33 One study showed that commercialization of marijuana in Colorado has resulted in lower risk perception.34 Legalization of marijuana in many places for therapeutic purposes also may have contributed to lower perception of marijuana risk.35,36 On the other hand, one study found that legalization was not related to perceived risk of monthly use of marijuana.37 A direct relationship was observed within each school grade of decreasing risk perception of marijuana use and increasing use of the drug. This observation is consistent with other studies.2,38-40 Across school grades, students who viewed marijuana as not risky were ≥9 times more likely to have ever used marijuana. The strength of the association was even stronger between no perceived risk of marijuana use and marijuana use in the past 30 days, indicating a dose-response relationship. Adolescence is a key risk period for drug abuse because it involves major transitional periods, such as new and demanding academic, social, and emotional challenges associated with school.41 In high school, students have the additional challenge of anticipating leaving home for college or work, which can heighten stress and, consequently, increase experimentation and reliance on drugs. It may be that some of the decreasing risk perception seen in late teen years is an attempt to justify use of marijuana as life’s challenges become greater. The Theory of Health Behavior indicates that health behaviors are directly influenced by anticipated benefits versus the costs of the action.42,43 In a study of 15 commonly used drugs, regular users rated the drugs’ potential harms and benefits. The study involved 5791 individuals from over 40 countries.44 Of several potential harms and benefits presented to the participants, marijuana was ranked consistently more beneficial and less harmful than the other psychoactive drugs, which helps explain why it is the most commonly used psychoactive drug in the world. The World Health Organization estimates that about 147 million people (2.5% of the world’s population), consumes cannabis, compared with 0.2% who use cocaine and 0.2% who use opiates.45 This study found that those who were more likely to view marijuana use as not risky were also more likely to perform poorer academically, to come from families where the guardian had lower education, not to live with a mother or father or to live with a stepfather, or to be a member of a racial/ethnic minority group. These were also the individuals most likely to use marijuana. Other research has shown these characteristics to be most commonly associated with marijuana use.46 High risk groups for marijuana use may perceive less risk from the behavior because they are not educated by their guardians about marijuana risks,
parental support and supervision may be absent, or poor engagement in school may cause them to miss drug prevention messages. Further, if those using marijuana do not value the importance of school learning for later life, although they may recognize that marijuana use can hurt their academic performance, this may not matter to them and, therefore, they would not view marijuana as a risky behavior. This may be increasingly true in families where the guardian has lower education, potentially resulting in education being less valued. Marijuana use is associated with poorer academic performance.47,48 Data from 3 large, long-running longitudinal studies in Australia and New Zealand, shows dose-response relationships between cannabis use and reduction in high-school completion and degree attainment, increased later cannabis dependence, use of other illicit drugs, and suicide attempts.48 In addition, early onset of marijuana use is related to lower educational attainment.49-51 Parent and peer perception of how wrong marijuana use is strongly correlated with the student’s perception of how wrong it is. Marijuana use is greater among those whose parents and/or peers use marijuana.46 There is a stronger correlation between peer perception of how wrong it is to use marijuana and how wrong the student perceives it to be than between the parents’ perception of how wrong it is compared with the students. The greater influence from friends may result if parents are not present to monitor and provide structure in their child’s life. The current study found that students were less likely to view marijuana use as very wrong if they did not live with their mother or father, or lived with a stepfather. Such situations often are associated with poor and inconsistent family management practices, more family conflict, low bonding, poor parental monitoring, and lack of structure and rules, each being a risk factor for marijuana use.52 Peer influence toward marijuana use has the potential to play an even bigger role in the student’s life in such situations. Hispanic students were less likely to perceive marijuana use as risky and more likely to have ever used marijuana or to have used it within the past 30 days. Although Hispanic parents were not less likely than their non-Hispanic counterparts to view marijuana use as very wrong, their friends were significantly less likely to view marijuana use as very wrong. The fact that Hispanic students tended to view education as less important for later life and have poorer academic performance than non-Hispanic students supports why they may be more likely to perceive marijuana as not risky. In addition, because Hispanic students are less likely to live with their father or more likely to live with a stepfather, there may be less family monitoring, which, in turn, may cause Hispanic students to be more likely to be influenced by peers.53 The higher consumption of marijuana among Hispanics
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Use of Marijuana and Changing Risk Perceptions compared with non-Hispanics (who are primarily Whites in our survey) is consistent with the National Survey on Drug Use and Health for adolescents.54 Conclusion The association between perceived risk and use of marijuana is complex. Some of the decrease in perceived risk may be because of legalization of marijuana for medical and recreational uses. Although the literature provides considerable evidence that marijuana use can have detrimental effects in terms of academic performance, low connectedness to school, truancy, and school dropout, if these areas are not valued as important, then marijuana may not be considered by the student to be risky behavior. Furthermore, challenging life changes through adolescence may cause many to adopt marijuana as a means of coping, with the perceived benefits outweighing perceived harm. This is especially true for students raised in households where education is less valued, and where there is less family monitoring and family structure, thereby leaving them more open to the influence of substance-using peers. Human Subjects Statement This secondary data analysis was deemed exempt from human subjects review. Conflict of Interest Statement None to declare. References
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