Supplementary Material for: Parental Smoking and Smoking Cognitions among Youth: A Systematic Review of the Literature

<b><i>Aims:</i></b> We summarized and discussed the empirical evidence for an association between parental smoking and smoking-related cognitions among youth and for the mediating role of smoking-related cognitions in the relation between parental and youth smoking behaviour. <b><i>Methods:</i></b> We conducted a systematic review of articles published between 1980 and February 2015 using the databases PsychInfo and PubMed. <b><i>Results:</i></b> The systematic search resulted in 41 eligible studies. Only 4 studies investigated smoking-related cognitions as putative mediators in the association between parental and youth smoking. The synthesis of evidence showed a mix of significant and non-significant associations between parental smoking and smoking-related cognitions among youth. A majority of results reported positive associations even when non-significant findings were found. However, studies that report an effect suggest that the effect may be quite modest. <b><i>Conclusion:</i></b> Empirical evidence does not confirm the commonly applied assertions of social learning theories that parental smoking increases the risk of youth smoking through the development of favourable smoking-related cognitions. Methodological and theoretical aspects that might explain the lack of consistent findings are discussed.