The role of parents in preventing adolescent alcohol and cannabis use

This thesis aimed to investigate the role of parents in preventing adolescent alcohol and cannabis use. First, we investigated the association of specific parental drinking patterns with 12-15 year olds' drinking. Only two out of six parental drinking patterns, i.e. having a heavy drinking father or having two heavy episodic drinking parents, predicted early and heavier adolescent drinking. In addition, adolescents were found to be less likely to drink alcohol when parents set strict rules regarding alcohol use, when they have constructive conversations with their parents about alcohol and when parents are aware of the harmfulness of adolescent drinking. These associations were similar across gender and educational tracks, yet stronger for older, compared to younger adolescents. Moreover, between 2007 and 2011, Dutch parents increasingly adopted strict alcohol-specific practices, with the exception of parents of 16-year old adolescents, while adolescent reports of lifetime and last month alcohol use decreased, except for 16-year olds. Third, in order to quantify the effectiveness of family interventions in preventing and reducing adolescent drinking, we conducted a meta-analysis of randomized controlled trials. Results suggest that the overall effect of family interventions on adolescent drinking is small, yet consistent and effective even at 48 months. Fourth, in a pilot study we examined the effect of an in-home family intervention (In control: No alcohol!, RCT), consisting of five magazines focusing on applying evidence based alcohol-specific parenting practices (N = 213, age = 11-12 years). Results on frequency of alcohol-specific communication, non-drinking agreements, parental monitoring and adolescent alcohol cognitions are promising, yet an additional RCT could not replicate its findings. Fifth, we found that in addition to general parenting practices, restrictive cannabis-specific rules are related to lower adolescent cannabis and hard drug rates. In addition, children of parents who ever used cannabis had a higher prevalence of cannabis use. However, restrictive cannabis-specific rules were equally related to a lower chance of adolescent cannabis use, independent of parental cannabis use. Sixth, a systematic review and meta-analysis of RCTs revealed that family interventions targeting parent-child dyads are likely to be effective in preventing and reducing adolescent cannabis use in general populations, but no evidence for effective prevention of hard drug use was found. We underline the need to strengthen the evidence-base with more trials, especially among at-risk populations. These findings have a number of implications: 1) parents and professionals must be aware that parental heavy drinking affects their offspring, resulting in earlier and heavier drinking, 2) future policy and prevention efforts should pay more attention to the quantity of alcohol consumed by adolescents and to alcohol prevention among adolescents aged 16 years and over, and 3) it may be time to shift research and prevention efforts towards at-risk adolescents, whose substance use is particularly high, whereas the available prevention efforts are sparse and evidence of its effectiveness is insufficient