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Paediatr Child Health. 2009 April; 14(4): 225–230.
PMCID: PMC2690535

Language: English | French

The role of economic and cultural status as risk indicators for alcohol and marijuana use among adolescents

Mark Lemstra, PhD PhD, Cory Neudorf, MD MHSc FRCPC, Ushasri Nannapaneni, MA, Norman Bennett, MSc, Christina Scott, BA, and Tanis Kershaw, BA (Hons)

Abstract

INTRODUCTION:

A number of reports suggest that Aboriginal cultural status is a major risk indicator for drug and alcohol use. The primary purpose of the present paper was to determine whether Aboriginal cultural status is independently associated with risk behaviours, such as marijuana use and alcohol abuse, among youth after multivariate adjustment for other factors, such as socioeconomic status.

METHODS:

Every student between grades 5 and 8 in Saskatoon, Saskatchewan, was asked to complete a questionnaire in February 2007. Logistic regression was used to determine the independent risk indicators associated with alcohol abuse and marijuana use.

RESULTS:

Four thousand ninety-three youth participated in the school health survey. At the cross-tabulation level, cultural status and neighbourhood income were both strongly associated with alcohol and marijuana use. After multivariate adjustment, the association between Aboriginal cultural status and alcohol abuse was not statistically significant (crude OR=3.52 to adjusted OR=0.80). For marijuana use, the association was significantly reduced (crude OR=9.91 to adjusted OR=2.79). After controlling for all other variables, results showed that low-income youth were 103% more likely to get drunk at least once and were 163% more likely to have tried marijuana at least once.

CONCLUSION:

To be more successful, future policies directed toward reducing risk behaviours among youth should consider neighbourhood income characteristics.

Keywords: Adolescents, Alcohol drinking, Alcohol-related disorders, Drugs, Marijuana, Socioeconomic factors

Résumé

INTRODUCTION :

Un certain nombre de rapports laisse supposer que la culture autochtone est un important indicateur de risque de consommation de drogue et d’alcool. Le présent article visait d’abord à déterminer si la culture autochtone s’associe en elle-même à des comportements à risque comme la consommation de marijuana et l’abus d’alcool chez les jeunes après rajustement multivarié compte tenu d’autres facteurs, tels que la situation socioéconomique.

MÉTHODOLOGIE :

Chaque élève de la 5e à la 8e année de la ville de Saskatoon, en Saskatchewan, a été invité à remplir un questionnaire en février 2007. La régression logistique a permis de déterminer les indicateurs de risque indépendants associés à l’abus d’alcool et à la consommation de marijuana.

RÉSULTATS :

Quatre mille quatre-vingt-treize (4 093) jeunes ont participé à l’enquête sur la santé en milieu scolaire. Dans les tableaux croisés, la situation culturelle et le revenu du quartier s’associaient tous deux fortement à la consommation d’alcool et de marijuana. Après rajustement multivarié, l’association entre la culture autochtone et l’abus d’alcool n’était pas statistiquement significative (RR brut=3,52 par rapport au RR rajusté=0,80). Pour ce qui est de la consommation de marijuana, l’association diminuait considérablement (RR brut=9,91 par rapport au RR rajusté=2,79). Après avoir contrôlé toutes les autres variables, les résultats ont démontré que les jeunes à faible revenu étaient à 103 % plus susceptibles de s’être saoulés au moins une fois et à 163 % plus susceptibles d’avoir pris de la marijuana au moins une fois.

CONCLUSION :

Pour être plus efficaces, les futures politiques visant à réduire les comportements à risque chez les jeunes devraient tenir compte des caractéristiques de revenu des divers quartiers.

The prevalence of risk behaviours, such as marijuana use and alcohol abuse, among youth in North America has been steadily increasing since the 1980s, with sharp inclines since the early 1990s (111). Alcohol is the drug of choice among North American adolescents, and it is used by more young people than tobacco or illicit drugs (1214). A review of American population-based studies (5,15) suggests that drug and alcohol risk behaviours start at approximately 10 years of age, and peak between 14 and 15 years of age. A national study (4) suggests that for Canadian youth who are 15 years of age, the prevalence of alcohol use is 25% for boys and 19% for girls. The prevalence of alcohol use for Canadian youth who are between 11 and 13 years of age is 12% for boys and 8% for girls (4). A Canadian addiction survey (16) indicated that 61.4% of youth between 15 and 17 years of age had used marijuana in their lifetime, and 37% had used it at least once in the past 12 months.

In 2004, The Centre for Addictions and Mental Health (Toronto, Ontario) reported that Aboriginal youth are two to six times at a higher risk for every alcohol-related problem compared with other youth (17). Results from the 2002 Alberta Youth Experience Survey (18) indicated that a higher percentage of Aboriginal youth compared with non-Aboriginal youth reported signs of alcohol abuse (34.5% and 12.3%, respectively), and twice as many Aboriginal youth between grades 7 and 9 had used marijuana compared with non-Aboriginal youth (52.1% and 26.8%, respectively). These data suggest that being of Aboriginal ethnicity increases the risk of marijuana use or alcohol abuse among adolescents.

Through an extensive literature search, the authors found no studies that reviewed the independent association between Aboriginal cultural status and marijuana use after multivariate adjustment. Only one American study (19) was found by the authors that reviewed the independent association of Aboriginal cultural status with alcohol use after multivariate adjustment for variables, such as socioeconomic status (SES). In this study, initial differences in alcohol use by cultural status were no longer statistically significant in the final multivariate model (19).

The primary purpose of the present paper was to determine whether Aboriginal cultural status is independently associated with the risk behaviours of marijuana use and alcohol abuse (being drunk) among youth after multivariate adjustment for other factors, such as SES.

METHODS

Every student attending school in the city of Saskatoon, Saskatchewan, between grades 5 and 8, were asked to complete a questionnaire in February 2007. There were 9958 youth registered in these grades. The survey instrument used in the study was taken from the National Longitudinal Survey for Children and Youth (NLSCY), which was developed by Statistics Canada (20,21). The scope of the NLSCY is comprehensive, dealing with multiple health, social and educational outcomes that have been validated for Canadian youth between 10 and 13 years of age (20,21).

Alcohol abuse was measured by the question, ‘Have you ever been drunk’, with dichotomous yes/no response categories; marijuana use was measured by the question, ‘Have you tried marijuana in the past 12 months’, with yes/no response categories. Cultural status was stratified as Caucasian, Aboriginal or other. Neighbourhood income was calculated with the 2001 census information to identify six contiguous low-income cut-off neighbourhoods compared with the rest of Saskatoon (20). Other covariates included were five SES variables, 10 demographic variables, 12 school-related variables, 25 behaviour-related variables, 13 health-related variables, 24 mental health variables, and 10 family and friends variables.

A five-stage informed consent protocol was employed, including both public and Catholic school boards, the principals of each individual school, the teacher from each individual classroom and each parent, as well as written informed consent from each youth. The classroom teacher (not the researchers) asked the students to complete the questionnaire in the classroom. At that time, the students were told that they were free to consent or not consent and were free to not complete any question that made them uncomfortable. This information was on the questionnaire as well. Students and parents who chose to not participate were not isolated in any way.

Cross-tabulations were performed with alcohol abuse and marijuana use and all other variables, but only the ones with significant associations are presented in Table 1. Two separate logistic regression models were built for alcohol abuse (being drunk) and marijuana use, with all other covariates. A hierarchical well-formulated front-wise modelling approach was used instead of a computer-generated stepwise algorithm (22). Stepwise models were built that started with cultural status and progressively included socioeconomic variables, demographics, school variables, behaviours, health status, mental health, and friends and family. In the final model, the unadjusted effect of each covariate was determined and entered one step at a time based on changes in the −2 log likelihood and the Wald test (23). The variables were tested independently in a hierarchical fashion, but are presented in blocks in the table for clarity. The final regression model included factors with beta values for which P<0.05 (23). Confounding was tested by comparing the estimated coefficient of the outcome variable from models containing the covariates with models not containing the covariates (23). Interaction was assessed with product terms (23). R2 was used to determine the proportion of variance in the outcome variable explained by the knowledge of the explanatory variables, but not as a measure of the appropriateness of the final model (23). Goodness-of-fit of the final model was assessed by the Hosmer-Lemeshow statistical test (23). The final results are presented as adjusted ORs with 95% CIs (23). All analyses were performed using the SPSS 16.0 (SPSS Inc, USA) software package.

TABLE 1
Cross-tabulations for variables, such as ‘have been drunk’ and ‘have tried marijuana’, among youth nine to 15 years of age in schools in Saskatoon, Saskatchewan

Ethics approval was obtained from the University of Saskatchewan Behavioural Research Ethics Board (BEH # 06–237).

RESULTS

Of the 9958 eligible respondents, 4093 (41.1%) youth participated in the school health survey. There were statistically significant differences between the respondents and nonrespondents with regard to sex and neighbourhood income. In Saskatoon, 51.2% of youth between five and 14 years of age are boys compared with 46.5% of the sample, and 9.9% of youth live in one of six low-income neighbourhoods compared with 2.5% of the sample. In all other cases, demographic census information corresponded with the sample.

At the cross-tabulation level, Aboriginal cultural status and neighbourhood income were both strongly associated with alcohol abuse and marijuana use among adolescents. For example, 16.7% of Aboriginal youth had been drunk at least once compared with 5.4% of Caucasians, and 21.5% of Aboriginal youth had tried marijuana in the past 12 months compared with 2.7% of Caucasians. Similarly, 30.1% of youth in the low-income neighbourhoods had been drunk compared with 5.8% of youth in the rest of Saskatoon, while 35.7% of youth in the low-income neighbourhoods had tried marijuana in the past 12 months compared with 3.8% of youth in the rest of Saskatoon. The other covariates associated with youth who reported having been drunk and youth who reported trying marijuana are provided in Table 1.

When the outcome measures were stratified by income and cultural status at the same time, it was evident that income reduced the association between cultural status and risk behaviours. For example, 30.3% of low-income Aboriginal youth had been drunk compared with only 13.2% of higher-income Aboriginal youth; 42.9% of low-income Aboriginal youth had tried marijuana compared with 16.2% of higher-income Aboriginal youth (Table 2).

TABLE 2
Stratified analysis: Cultural status by neighbourhood income and the outcome measures

A hierarchical model-building strategy is presented by blocks in Tables 3 and and4.4. At the first stage of model building, the OR for Aboriginal cultural status for alcohol abuse (being drunk) reduced from 3.52 to 2.45 (a 107% reduction in the OR) when adjusted for neighbourhood income alone. Introduction of age did not have an impact on the model. On introducing the school variables (skipped school and have been bullied), the OR of Aboriginal youth being drunk reduced to 1.36. When self-esteem was added to the model, the OR further dropped to 1.28. When the covariates – friends tried marijuana and friends drank alcohol – were added to the model, the independent association between Aboriginal cultural status and being drunk became protective, although not statistically significant (Table 3).

TABLE 3
Stepwise modelling: Crude and adjusted (adj) estimates of ‘having been drunk’ among adolescents nine to 15 years of age in schools in Saskatoon, Saskatchewan
TABLE 4
Stepwise modelling: Crude and adjusted (adj) estimates of ‘having tried marijuana’ among adolescents nine to 15 years of age in schools in Saskatoon, Saskatchewan

For marijuana use, the OR reduced from 9.91 to 6.88 after controlling for neighbourhood income alone (a reduction of 303% in the OR). On adding the school variables (skipped school, suspended from school and been bullied) the OR was reduced to 3.99. After adding the mental health variables (suicide ideation and self-esteem), the OR dropped to 3.61. When the covariate – friends tried marijuana – was added to the model, the OR for Aboriginal cultural status reduced to 2.79. With the addition of all the covariates to the model, the independent association between Aboriginal cultural status and marijuana use reduced from 9.91 to 2.79 (a reduction of 712%) (Table 4).

Neighbourhood income was a direct confounder to the relationship between Aboriginal cultural status and alcohol abuse or marijuana use. Interaction was not present in either of the final models.

The R2 for the final models were 0.159 for alcohol abuse and 0.143 for marijuana use, suggesting a reasonable explanation of the proportion of variance in the outcome variable explained by the knowledge of the explanatory covariates. The goodness-of-fit test results – 0.380 for alcohol abuse and 0.856 for marijuana use – suggest that the final models are appropriate and that the predicted values are accurate representations of the observed values in an absolute sense. The estimated slope coefficients and standard errors for the models are small and, as such, colinearity is not suspected.

DISCUSSION

In light of the growing trend in alcohol abuse and marijuana use among adolescents, the authors assessed the independent association between cultural status and risk behaviours, while controlling for other covariates. After stratifying by income, the prevalence of alcohol abuse and marijuana use reduced substantially for both Caucasians and Aboriginal youth. Stratification for income alone did not explain the variance that was still present in higher-income Aboriginal youth in comparison with higher-income Caucasian youth. Although income is an important risk indicator, it does not explain all of the variance, necessitating multivariate regression with more variables in the models than income alone.

After multivariate regression, the common risk indicators for alcohol abuse and marijuana use were low-income neighbourhoods, skipping school, being bullied, low self-esteem and having friends that have tried marijuana. The individual differences between the two models were age and if their friends drank alcohol (for the alcohol model), while being suspended from school and suicide ideation were additional covariates for the marijuana model after multivariate adjustment. Our study found a substantially reduced association between Aboriginal cultural status and marijuana use, and no association with alcohol abuse.

Our results challenge the common notion that the increase in the prevalence of risk behaviours, such as alcohol abuse and marijuana use, is independently associated with Aboriginal cultural status (24,25). After controlling for neighbourhood income alone in the models, there was a significant reduction in the OR for alcohol abuse (3.52 to 2.45) and marijuana use (9.91 to 6.88) among Aboriginal youth. After further multivariate adjustment, the association between Aboriginal cultural status and risk behaviours substantially reduced.

A recent systematic literature review (26) found that marijuana use and alcohol abuse among adolescents did not appear to be significantly associated with SES. The studies in this review used a range of definitions to capture SES (ie, family income, parents’ education, parents’ occupation and neighbourhood characteristics). However, there was only one study (26) in the pool of 29 studies reviewed that used neighbourhood characteristics as an SES variable for both alcohol abuse and marijuana use. This study found significant differences between neighbourhood schools stratified by income for both alcohol abuse and marijuana use, which supports our finding. Future research should investigate specific pathways that may explain the relationship between neighbourhood characteristics and risk behaviours.

Other research has found a positive association between peer influence and drug and alcohol usage in adolescents (27,28). Two American national longitudinal studies (29,30) on adolescent health found self-esteem, school connectedness, school attendance, SES, emotional distress, suicidality and history of victimization/witnessing violence to be risk indicators for both alcohol abuse and marijuana use. The results found in these studies are consistent with our results.

The present study had some limitations. First, written consent was obtained for 41.1% of the eligible students. The five-stage consent protocol served as an administrative barrier in achieving higher participation rates. It is important to note that the response bias by sex and neighbourhood income might have an impact on the representativeness of the sample and subsequent results. The prevalence of drinking by sex was not significant, so the impact of sex is negligible. However, the sample had under-representation from low-income children and, as such, likely reduced estimates of overall prevalence. The main purpose of the study, however, was to determine risk indicators for drug use and alcohol abuse, not prevalence rates of drug and alcohol. Second, the study does not have adequate representation from boys and low-income neighbourhoods. However, the absence of any exclusion criteria provides a real-world sample. Third, the study design is cross-sectional and can only describe the associations and not causations.

Adolescence is a period of biological, intellectual and psychosocial development. Many lifelong skills and behaviour patterns are established during this time. Thus, interventions to change behaviours need to occur at an early age (31). Furthermore, it is established that school-based interventions are the most effective in altering adolescent risk behaviours (32). However, the most effective primary prevention programs for reducing marijuana use and alcohol abuse among adolescents, who are between 10 to 15 years of age, are comprehensive school-based primary prevention programs that include anti-drug information combined with refusal skills, self-management skills and social skills training (33).

CONCLUSIONS

Our study suggests that income status is strongly associated with adolescent risk behaviour and, as such, interventions to prevent or reduce these behaviours should consider income during intervention design. Aboriginal cultural status has a greatly reduced role in risk behaviours after multivariate adjustment. The findings in the study suggest that interventions should focus on at-risk populations in low-income neighbourhoods because a major risk indicator (income) is modifiable (ie, policy changes through taxes and social programs), whereas cultural status is not.

Acknowledgments

The research was supported by a grant from the Canadian Institutes of Health Research (Grant #149320). The authors thank George Rathwell, Gordon Martell, Gary Beaudin, Ceal Tournier, Terry Dunlop, Lynne Warren and Stephanie Karst for their assistance.

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