Activity levels and drug use in a sample of Spanish adolescents

Authoress: Noelia L. AleixandreT, Miguel J. Perello del Río, Alfonso L. Palmer Pol

Balearic Islands University, Department of Psychology, Ctra. Valldemossa, km 7.5, 07122 Palma de Mallorca, Spain



The importance of adolescents taking part in various activities as a protective factor in substance consumption has been demonstrated over time. The objective of this paper is to analyze a sample of 1378 adolescents and the explanatory capacity of participating in different activities in relation to present-day alcohol, cannabis and tobacco consumption. Count variables were used as response variables, thus the Poisson Regression Model was applied in the analysis, within the context of a Generalized Linear Model. The results of the research demonstrate the explanatory value and differences in explanatory roles of each activity in connection with each the substances studied. D 2005 Elsevier Ltd. All rights reserved.

Keywords: Substance use; Substance-free behaviour; Adolescent; Alcohol; Tobacco; Cannabis

1. Introduction

According to the Diagnostic and Statistical Manual of Mental Disorder (DSM-IV-TR, 2002), two of the criteria for substance dependency are related to dependent subjects’ activity levels. It appears clear that substance dependent and abusive subjects decrease their educational, work-related, domestic or recreational activities, relegating them to second place in favour of activities related to drug consumption, as the latter end up acquiring a greater reinforcing power. From the functional analysis of behaviour, this decline in non-drug consumption-related activities explains why substances positively or negatively reinforce behaviours associated with their consumption and the external or internal stimulus situations associated with them.

One study conducted with 206 subjects with an average age of 18.89 who had consumed alcohol or other drugs in the preceding 30 days showed results that demonstrated that the reinforcement that drugfree activities provide subjects has a predictive value on drug consumption behaviours. It found a negative relationship between the reinforcing level of drug-free activities and drug consumption, to such a degree that frequency of consumption increases if the amount of reinforcement of the drug-free activity perceived by the subject decreases (Correia, Benson, & Carey, 2005; Correia, Simons, Carey, & Borsari, 1998).

However, on the other hand, when dealing with adolescents, and drug consumption behaviour is seen within a wide range of health risk behaviours, it was found that activity level is not as decisive. It seems that adolescents involved in multiple health risk behaviours were also involved in many other positive behaviours (Lindberg, Boggess, & Williams, 1999). Behavioural theories assume that drug or alcohol consumption should be understood within the context in which that behaviour occurs.

The objective of this study was to verify the relation between participating in pleasurable or reinforcing activities and the consumption of different addictive substances. It specifically aimed to prove the explanatory capacity of participating in different activities in present day substance consumption.

2. Method

The sample was made up of 1378 subjects of which 43.7% were men and 56.3% were women. Ages oscillated between 13 and 19 years of age and the average age of the subjects was 15.67 years of age. Of the 1378, 50.2% consumed fermented beverages, 52.3% consumed distilled beverages, 44.6% consumed cannabis cigarettes and 48.4% consumed cigarettes. In all the cases we are with nonproblematic sample. The adolescents were asked for their informed consent verbally and were informed that their responses were confidential. A differentiation was made in the alcohol variable between fermented beverages (wine, beer. . .) and distilled beverages (whisky, vodka. . .) and their different associated graduations were taken into account. The measures were all subsequently converted to standard beverage units (SBU, when one SBU equals 10 g of ethanol) in order to carry out the analysis.

The Generalized Linear Model was used as a reference framework to analyze data whose response variable is a count and consequently the model to apply is the Poisson Regression. This model requires compliance with equidispersion. The analysis was conducted with the Stata 8.0 and SPSS 11.0.

3. Results

3.1. Descriptive

Subjects who have tried drugs participate in a low total number of activities (0–2), in a proportion statistical significantly higher than those who have not tried them (v2=10.69; p b.001). Subjects’ responses showed that those who have not tried drugs visit libraries and sports centers more often, while subjects who have tried drugs presented statistically higher values in visiting pubs and discotheques (v2=33.057; p b.001). In our sample, there were no statistically significant differences in subjects’ gender and having tried the different substances or not.

3.2. Modelling

One way to verify equidispersion is through the regression test proposed by Cameron and Trivedi (1990). After verifying the non-compliance of equidispersion and executing various possible fits, the model, which presents the best fit in our data, is the Negative Binomial Regression Model.

As the study works with count data, interpretation cannot be conducted directly on the model’s coefficients, due to the lack of linearity; thus the transformation to IRR (Incidence Rate Ratio) through the exponentiation of the coefficients, exp(b), was used as the interpretation of this transformation is similar to the odds ratios, when the remaining variablesare always maintained constant.

Table 1, shows the variables for all the substances, which appear significant. Social activities and the age of first use appear as explanatory variables in the consumption of fermented beverage. Subjects who claimed to participate customarily in social activities consume 54% more beverages than those who claimed not to participate in these activities. Furthermore, consumption decreases 5% for each year the
age of first year increases.

Social activities, families and trips appear significant in distilled beverages. Subjects who indicated participating in social activities consume 34% more than those would do not participate in this type of activity, producing an expected change of 1.8 more drinks per week compared to those who do not customarily participate in these activities. Subjects who indicated participating in family activities consume 35% less than those who did not participate in these activities, producing an expected change in the number of drinks of 2.5 fewer standard drinks per week. Those who indicated taking trips increased their consumption of distilled beverages by 36% compared to those who do not participate in these

Table 1

Variables for all the substances

The response variables utilised in the research were the amounts consumed in the last week.

activities. The age of first use also appears to influence consumption of these substances, specifically a decrease of 9% for each year first use increases. Furthermore, a trend in the significance of cultural activities can also be indicated. Subjects who participated in cultural activities present an expected change in the number of distilled drinks of 1.18 fewer standard drinks than subjects who do not
participate in this type of activity.

Cultural activities, trips and the age of first use appear as explanatory variables in cannabis consumption. Subjects who say that they customarily participate in cultural activities consume 48% less than subjects who do not participate in these activities (2.24 fewer cannabis cigarettes per week). Participating in activities related to trips increases consumption by 65% compared to those who do not participate in this type of activity (an expected change in consumption of 2.36 more cannabis cigarettes per week). As for the age of first use, consumption decreases by 27% for each year first use increases.

Only sports activities appear significant in the consumption of tobacco. Subjects who indicated participating in sports activities consume 59% less tobacco than subjects who do not participate in sports activities, which translates into an expected value of 20 fewer cigarettes per week. The remaining activities in our sample do not appear as explanatory in tobacco consumption.

4. Discussion

The results of this study are consistent with prior research indicating the need for alternative activities to substance consumption (Carroll, 1996; Vuchinich & Tucker, 1988). In general, subjects who consumed one of the different substances participate in fewer drug-free activities (Van Etten, Higgins, Budney, & Badger, 1998).

The age of first use influences current consumption of different substances. In all cases it appears that later first use of substance consumption leads to lower consumption and as Carroll (1996), among others, indicates, subjects who participate in more non-drug related activities begin consumption later. Activities not related to drugs are thus converted into a protective factor, because later first use of a drug means a delay associated with the consumption of other, potentially more dangerous drugs (Kandel & Yamaguchi, 1985; Yu & Williford, 1992). Nevertheless, it can be verified how the influence of this variable on each one of the substances varies differentially, as later first use means a greater decrease in the consumption of distilled beverages than in fermented beverages, but cannabis is where the greatest influence as regards a greater decrease in consumption can be observed.

Higher levels of activities are not always related to a lower consumption of addictive substances; participating in social activities appears related to greater substance consumption, specifically alcohol (distilled and fermented) and the weight of this variable in fermented beverages is much greater than in distilled beverages. On the other hand, taking trips is also predictive of greater cannabis and distilled beverage consumption and the influence of this variable is greater on cannabis.

Although the variables introduced in the model, which explain the consumption of each one of the substances, are different, all of them appear in the same sense. As previously indicated, behavioural theories assume that drug consumption must be understood within the context it takes place in. Within the context, the availability of alternative reinforces incompatible with consumption and an environmental restriction to obtain substances is determinant (Vuchinich & Tucker, 1996). Thus, the increase in proven protective activities, as well as the proposal of non-drug use related activities must be taken into account in preventing and treating problems related to addictive substances. Providing young people with easy access to alternatives activities to consuming drugs, activities they can participate in frequently, allows the age of first use in consumption to be delayed as well as consumption to be reduced. This research was partially supported by the National Plan on Drugs, Spain.


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