A randomized controlled trial of a brief motivational enhancement for non-treatment-seeking adolescent cannabis users.

Evidence for negative effects of early-onset cannabis use has led to a need for effective interventions targeting adolescent cannabis users. A randomized controlled trial of an Australian two-session intervention based on motivational interviewing (the ACCU, or Weed-Check in Dutch) was replicated in a larger Dutch sample of 119 non-treatment-seeking adolescent cannabis users. Outcome measures at the 3-month follow-up were quantity and frequency of cannabis use, symptoms of dependence, stage of change, and psychosocial functioning. Changes in all measures were in the expected direction, yet not significant. In moderation analyses, heavier cannabis users at baseline receiving the Weed-Check had greater reductions in cannabis use than those in the control condition. These results suggest that the Weed-Check might be beneficial for heavier cannabis-using adolescents. Further research is needed to confirm these results in a sample of adolescent heavy cannabis users and to examine the relationship between MI skills of prevention workers and outcome.

Risk moderation of a parent and student preventive alcohol intervention by adolescent and family factors: a cluster randomized trial.

OBJECTIVE: To examine risk moderation of an alcohol intervention targeting parents and adolescents. DESIGN: A cluster randomized trial including 2937 Dutch early adolescents (m=12.68years, SD=0.51) and their parents randomized over four conditions: parent intervention, student intervention, combined parent-student intervention, and control group. SETTING: 152 classes of 19 high schools in The Netherlands (2006). METHOD: Moderators at baseline (adolescent: gender, educational level and externalizing behavior; parent: educational level and heavy alcohol use) were used to examine the differential effects of the interventions on onset of (heavy) weekly drinking at 22-month follow-up. RESULTS: The combined intervention effectively delayed the onset of weekly drinking in the general population of adolescents, and was particularly effective in delaying the onset of heavy weekly drinking in a higher-risk subsample of adolescents (i.e. those attending lower levels of education and reporting higher levels of externalizing behavior). CONCLUSION: Present and previous results have established the combined intervention to be universally effective in postponing weekly alcohol use among Dutch adolescents, with an added effect on postponing heavy weekly drinking in high risk subgroups. Therefore, implementation of this intervention in the general population of schools in The Netherlands is advised. TRIAL REGISTRATION: NTR649.

Mediation and moderation effects of an in-home family intervention: the "in control: no alcohol!" pilot study.

The aim of this study was to examine the effect of a theory-based in-home family intervention (In control: No alcohol!) on adolescent alcohol cognitions via its putative mediators using a randomized controlled design. In the South Holland region of the Netherlands, a total of 213 children (11-12 years) and their mothers were randomly assigned to the prevention program (108 dyads) and the control condition (105 dyads). Mediation effects were analyzed using pretest and two follow-up measurements (5 and 12 months after baseline). A path model was estimated (using Mplus) to examine the effect of the intervention on the putative mediators (frequency- and quality of mother-child communication, rules about alcohol, establishing a nondrinking agreement, and parental monitoring of the child's whereabouts). Outcomes were adolescents' perceived harmfulness of drinking and intention to drink. Multigroup analyses were performed to examine potential differences across gender. The program led to an increase in frequency of alcohol-specific communication, nondrinking agreements, and parental monitoring. Moreover, adolescents in the experimental condition perceived drinking to be more harmful and had less intention to drink compared to adolescents in the control condition. The effect of the program on adolescent alcohol cognitions was significantly mediated through having more frequent conversations about alcohol, yet only among boys. Although results on actual drinking need to be added, findings indicate that this relatively inexpensive, easy-to-administer home intervention is promising.

A cluster randomized trial on the effects of a parent and student intervention on alcohol use in adolescents four years after baseline; no evidence of catching-up behavior.

OBJECTIVE: It is questioned whether the alcohol prevention program "Prevention of Alcohol use in Students" (PAS) is effective in reducing the prevalence of heavy weekend drinking and the amount of drinking among adolescents at the age at which they are allowed to buy alcohol in The Netherlands (16 years). In addition, it is questioned whether the intervention effects are attributed to a delay in onset earlier in adolescence or to the development of skills due to the PAS intervention (mediation analyses). DESIGN: A cluster randomized trial including 3490 Dutch early adolescents (M age=12.66, SD=0.49) and their parents randomized over four conditions; 1) parent intervention, 2) student intervention, 3) combined intervention and 4) control group. OUTCOME MEASURES: Outcome measures were prevalence of heavy drinking and amount of weekend drinking measured at age 16, 50 months after baseline. RESULTS: Only when parents and students were targeted simultaneously could the prevalence of heavy weekend drinking (b=-.44, p=.02) and the amount of alcohol use (b=-.24, p=.02) be reduced. No significant effects of the separate parent and student interventions were found. The effect of the combined PAS intervention on heavy weekend drinking and amount of drinking can be attributed to respectively the increase in self-control and strict parenting, and a delayed alcohol initiation earlier in adolescence. CONCLUSIONS: The current study confirms the effectiveness of the combined PAS intervention up to the legal drinking age of 16. The results underline that postponing the onset of drinking among early adolescents is not only crucial for health development in the short term, but also impacts the development of a healthier drinking pattern later on.

The influence of paternal and maternal drinking patterns within two-partner families on the initiation and development of adolescent drinking.

As it is still unclear to what extent parental drinking is a predictor of children's alcohol use, we tested the association of specific paternal and maternal drinking patterns with both initiation and development of adolescent alcohol use. Longitudinal data (four annual measurements) of parent-child dyads (N=2319) have been used. Parental drinking patterns have been identified using latent class analysis. The association of parental drinking patterns with the initiation and development of 12-15 year olds' drinking have been examined with latent growth curve modeling. Only two out of six parental drinking patterns were related to adolescent drinking. That is, having a heavy drinking father or two heavy episodic drinking parents particularly predicts early and heavier adolescent drinking. When controlled for parenting behaviors and background variables, such as adolescent gender, age and socioeconomic status (SES), these findings remained significant. Interaction analyses revealed that the influence of parental heavy (episodic) drinking differs across gender and is especially strong among adolescents with lower SES. Thus, parental heavy (episodic) drinking, and not so much the frequency of drinking, predicts the initiation and development of alcohol consumption in their offspring. Parents and professionals must be aware that parental heavy drinking affects their offspring, particularly adolescents with lower SES, resulting in earlier and heavier drinking among this high-risk group.

Developmental alcohol-specific parenting profiles in adolescence and their relationships with adolescents' alcohol use.

Previous studies on general parenting have demonstrated the relevance of strict parenting within a supportive social context for a variety of adolescent behaviors, such as alcohol use. Yet, alcohol-specific parenting practices are generally examined as separate predictors of adolescents' drinking behavior. The present study examined different developmental profiles of alcohol-specific parenting (rule-setting, quality and frequency of communication about alcohol use) and how these patterns relate to the initiation and growth of adolescents' drinking. A longitudinal sample of 883 adolescents (47 % female) including four measurements (between ages 12 and 16) was used. Latent class growth analysis revealed that five classes of parenting could be distinguished. Communication about alcohol appeared to be fairly stable over time in all parenting classes, whereas the level of rule-setting declined in all subgroups of parents as adolescents grow older. Strict rule-setting in combination with a high quality and frequency of communication was associated with the lowest amount of drinking; parents scoring low on all these behaviors show to be related to the highest amount of drinking. This study showed that alcohol-specific rule-setting is most effective when it coincides with a good quality and frequency of communication about alcohol use. This indicates that alcohol-specific parenting behaviors should be taken into account as an alcohol-specific parenting context, rather than single parenting practices. Therefore, parent-based alcohol interventions should not only encourage strict rule setting, the way parents communicate with their child about alcohol is also of major importance.

Differential impact of a Dutch alcohol prevention program targeting adolescents and parents separately and simultaneously: low self-control and lenient parenting at baseline predict effectiveness.

To test whether baseline levels of the factors accountable for the impact of the Prevention of Alcohol use in Students (PAS) intervention (self-control, perceived rules about alcohol and parental attitudes about alcohol), moderate the effect of the intervention. A cluster randomized trial including 3,490 Dutch early adolescents (M age=12.66, SD=.49) and their parents randomized over four conditions: 1) parent intervention, 2) student intervention, 3) combined intervention and 4) control group. Moderators at baseline were used to examine the differential effects of the interventions on onset of (heavy) weekly drinking at 34-month follow-up. The combined intervention was only effective in preventing weekly drinking among those adolescents who reported to have lower self-control and more lenient parents at baseline. No differential effect was found for the onset of heavy weekly drinking. No moderating roles of self-control and lenient parenting were found for the separate student and parent interventions regarding the onset of drinking. The combined intervention is more effective among adolescents with low-self control and lenient parents at baseline, both factors that were a specific target of the intervention. The relevance of targeting self-control in adolescents and restrictive parenting is underlined.

Results of the 'in control: no alcohol!' pilot study.

More than 50% of Dutch 12-year olds already started drinking. Since it is known that delaying the onset of alcohol use results in a lower risk of alcohol-related problems, the recently developed 'In control: No alcohol!' prevention program is targeted at elementary school children and their mothers. In this pilot study, the success of program implementation and impact of the program on quality of alcohol-specific communication, rules and monitoring were evaluated, using a randomized controlled design. A total of 108 children (11-12 years) and their mothers participated in the prevention program, while the control group consisted of 105 dyads. Families participating in the experimental condition showed an increase in frequency of alcohol-specific communication and 75% of the dyads reported that they took part in at least 3 of 5 magazines, suggesting implementation was successful. The program led to an increase in quality of communication but only for those dyads in which mothers' alcohol use was above average. The program led parents to set up a non-drinking contract with their children and to monitor their children more closely. Results are promising but need to be replicated in a larger longitudinal study.

Effectiveness of the home-based alcohol prevention program "In control: no alcohol!": study protocol of a randomized controlled trial.

BACKGROUND: In the Netherlands, children start to drink at an early age; of the Dutch 12-year olds, 40% reports lifetime alcohol use, while 9.7% reports last-month drinking. Starting to drink at an early age puts youth at risk of developing several alcohol-related problems later in life. Recently, a home-based prevention program called "In control: No alcohol!" was developed to delay the age of alcohol onset in children. The main aim of this project is to conduct a Randomized Controlled Trial (RCT) to evaluate the effectiveness of the program. METHODS/DESIGN: The prevention program will be tested with an RCT among mothers and their 6 grade primary school children (11-12 years old), randomly assigned to the prevention or control condition. The program consists of five printed magazines and an activity book designed to improve parental alcohol-specific socialization. Parent-child dyads in the control group receive a factsheet information brochure, which is the standard alcohol brochure of the Trimbos Institute (the Netherlands Institute for Mental Health and Addiction).Outcome measures are initiation of alcohol use (have been drinking at least one glass of alcohol), alcohol-specific parenting, susceptibility to drinking alcohol, alcohol expectancies, self-efficacy, and frequency and intensity of child alcohol use. Questionnaires will be administered online on secured Internet webpages, with personal login codes for both mothers and children. Mothers and children in both the experimental and control condition will be surveyed at baseline and after 6, 12, and 18 months (follow-ups). DISCUSSION: The present study protocol presents the design of an RCT evaluating the effectiveness of the home-based "In control: No alcohol!" program for 6 grade primary school children (11-12 years old). It is hypothesized that children in the prevention condition will be less likely to have their first glass of alcohol, compared to the control condition. When the prevention appears to be effective, it can easily and relatively quickly be implemented as a standard alcohol prevention program on a large scale. TRIAL REGISTRATION: Nederlands Trial Register NTR2564.

Why target early adolescents and parents in alcohol prevention? The mediating effects of self-control, rules and attitudes about alcohol use.

AIMS: To examine the effects of a parent and student intervention offered separately and simultaneously (PAS) on onset of weekly drinking via its putative mediators. DESIGN: A randomized trial with four conditions; (1) parent intervention, (2) student intervention, (3) combined parent-student intervention and (4) control group. SETTING: High schools selected randomly, located in different areas. PARTICIPANTS: A total of 2937 early adolescents (mean age = 12.6, standard deviation = 0.49) and their parents. MEASUREMENTS: Mediation effects were analysed using pretest data and two follow-up measurements (10 and 22 months after baseline). A path model was estimated (Mplus) to examine the effect of the interventions on adolescent-reported mediators (self-control, perceived parental rules and attitudes about alcohol) and parent-reported mediators (parental rules and attitudes about alcohol). Outcome was onset of weekly drinking. FINDINGS: The parent intervention modified rules and attitudes about alcohol as reported by parents. An indirect effect of the parent intervention via parental rules was found. The combined intervention affected both adolescent-reported and parent-reported rules and attitudes about alcohol and adolescents' perceived self-control, yet only perceived rules and self-efficacy, as reported by adolescents, and parental attitudes mediated the association between the combined intervention and onset of weekly drinking. No significant effects were found of the separate student intervention on the mediating factors. CONCLUSIONS: The PAS programme proved to be effective as predicted by the theoretical assumptions underlying the interventions. Interventions with parents and adolescents to prevent adolescent alcohol consumption may usefully target parental rules about alcohol and adolescents' self-confidence.

Alcohol-specific socialization practices and alcohol use in Dutch early adolescents.

The present study examined the associations of alcohol-specific socialization practices and heavy parental drinking with alcohol use in early adolescents. Cross-sectional nationwide survey data from 2599 parent-adolescent (mean age=12.16) dyads were used to conduct logistic regression analyses. Onset of alcohol use as well as infrequent and regular drinking were associated with tolerant rules and attitude as reported by adolescents, and by a tolerant attitude as reported by parents. In contrast to former studies including middle and late adolescents, parental alcohol use was not found to be associated with early adolescent alcohol use, nor did parental alcohol use influence the impact of parental rules. Restrictive alcohol-specific socialization was, independent of parental alcohol use, related to absence of (regular) early adolescent drinking. Thus, this study demonstrated that in early adolescence alcohol-specific parenting is more important for adolescent drinking than parental alcohol use.

Preventing heavy alcohol use in adolescents (PAS): cluster randomized trial of a parent and student intervention offered separately and simultaneously.

AIMS: To evaluate the effectiveness of two preventive interventions to reduce heavy drinking in first- and second-year high school students. DESIGN AND SETTING: Cluster randomized controlled trial using four conditions for comparing two active interventions with a control group from 152 classes of 19 high schools in the Netherlands. PARTICIPANTS: A total of 3490 first-year high school students (mean 12.68 years, SD=0.51) and their parents. Intervention conditions (i) Parent intervention (modelled on the Swedish Örebro Prevention Program) aimed at encouraging parental rule-setting concerning their children's alcohol consumption; (ii) student intervention consisting of four digital lessons based on the principles of the theory of planned behaviour and social cognitive theory; (iii) interventions 1 and 2 combined; and (iv) the regular curriculum as control condition. Main outcome measures Incidence of (heavy) weekly alcohol use and frequency of monthly drinking at 10 and 22 months after baseline measurement. FINDINGS: A total of 2937 students were eligible for analyses in this study. At first follow-up, only the combined student-parent intervention showed substantial and statistically significant effects on heavy weekly drinking, weekly drinking and frequency of drinking. At second follow-up these results were replicated, except for the effects of the combined intervention on heavy weekly drinking. These findings were consistent across intention-to-treat and completers-only analyses. CONCLUSIONS: Results suggest that adolescents as well as their parents should be targeted in order to delay the onset of drinking, preferably prior to onset of weekly drinking.

Body mass index and body weight perception as risk factors for internalizing and externalizing problem behavior among adolescents.

PURPOSE: To examine the relationship between body mass index (BMI), body weight perception (BWP), and indicators of internalizing and externalizing distress and social, attention and thought problems in a large representative sample of Dutch youth. METHODS: A total of 1826 pupils in the eighth grade of primary education and 5730 students in the first four years of secondary education gave their height and weight to obtain an estimate of their BMI. They reported their evaluation of their body weight and completed Achenbach's Youth Self-Report (YSR) (1991), which assesses eight types of problem behavior. Data were analyzed in a multivariate framework with BMI and BWP as predictors and the YSR scores on different kinds of problem behavior as dependent variables, controlling for background characteristics. RESULTS: Both BMI and BWP are associated with internalizing and externalizing problem behavior, and social, attention and thought problems. Multivariate tests show that BWP is more closely linked to problem behavior than BMI. Adolescents who were either underweight or overweight but considered themselves in good shape had no more problems than the group with normal BMI and BWP 'good'. The perception of being 'too thin' and particularly the perception of being 'too heavy' best predict problem behavior in both male and female adolescents. Overweight youngsters with an adequate perception of their weight have less somatic complaints than their normal-weight peers who perceive themselves as too heavy, but they show higher withdrawnness, social problems, and anxiety/depression. CONCLUSIONS: Adolescent girls are more dissatisfied with their weight than boys; however, the relationship between weight perception and problem behavior is the same for both genders.

Estimating non-response bias in a survey on alcohol consumption: comparison of response waves.

AIMS: According to 'the continuum of resistance model' late respondents can be used as a proxy for non-respondents in estimating non-response bias. In the present study, the validity of this model was explored and tested in three surveys on alcohol consumption. METHODS: The three studies collected their data by means of mailed questionnaires on alcohol consumption whereby two studies also performed a non-response follow-up. RESULTS: Comparisons of early respondents, late respondents and non-respondents in one study showed some support for 'the continuum of resistance model', although another study could not confirm this result. Comparison of alcohol consumption between three time response groups showed no significant linear pattern of differences between response waves. CONCLUSIONS: The hypothesis that late respondents are more similar to non-respondents than early respondents, could not be confirmed or rejected. Repeated mailings are effective in obtaining a greater sample size, but seem ineffective in improving the representativeness of alcohol consumption surveys.