Does smoking among friends explain apparent genetic effects on current smoking in adolescence and young adulthood?

Abstract

We used data from a prospective cohort study of twins to investigate the influence of unmeasured genetic and measured and unmeasured environmental factors on the smoking behaviour of adolescents and young adults. Twins were surveyed in 1988 (aged 11 -18 years), 1991, 1996 and 2004 with data from 1409, 1121, 732 and 758 pairs analysed from each survey wave, respectively. Questionnaires assessed the smoking behaviour of twins and the perceived smoking behaviour of friends and parents. Using a novel logistic regression analysis, we simultaneously modelled individual risk and excess concordance for current smoking as a function of zygosity, survey wave, parental smoking and peer smoking. Being concordant for having peers who smoked was a predictor of concordance for current smoking (Po0.001). After adjusting for peer smoking, monozygotic (MZ) pairs were no more alike than dizygotic pairs for current smoking at waves 2, 3 and 4. Genetic explanations are not needed to explain the greater concordance for current smoking among adult MZ pairs. However, if they are invoked, the role of genes may be due to indirect effects acting through the social environment. Smoking prevention efforts may benefit more by targeting social factors than attempting to identify genetic factors associated with smoking. Smoking is an important cause of preventable mortality and morbidity in later life (Ezzati and Lopez, 2004), so there is a need to understand the factors associated with its uptake and establishment. Twin studies have the potential to identify whether genetic factors might play a role in explaining individual variation in smoking behaviours. The observation that identical (monozygotic; MZ) twin pairs are more similar than same-sex non-identical (dizygotic; DZ) twin pairs is often interpreted as showing that genetic factors play a role, because this finding is consistent with such an explanation under the assumptions of the classic twin model (CTM). One of the main assumptions of the CTM is that the effects of the shared environment on the relevant trait are the same for MZ and DZ pairs (the equal environments assumption (EEA)). Under this assumption, any greater similarity for MZ pairs compared with DZ pairs is attributed to their greater genetic similarity.Using the CTM, studies of the smoking behaviour of adult twins have been interpreted as showing that genetic factors play a major role in both initiation and persistence of smoking (Carmelli et al,

Socially acquired nicotine self-administration with an aversive flavor cue in adolescent female rats

“…In contrast, many lines of evidence support the role of social environment. For example, peer smoking is one of the strongest predictors of smoking initiation (Greenlund et al 1997; White et al 2008). The social learning theory (Akers 1977), which emphasizes that the definition of rewards/punishments associated with the behavior is transferred between individuals, is well supported by data on smoking initiation (Spear and Akers 1988; Flay et al 1994).…”

“…The majority of first-time cigarette use occurs in the presence of friends (Friedman et al 1985; Hahn et al 1990), and peer smoking is one of the strongest predictors of smoking initiation (Greenlund et al 1997; White et al 2008). Further, being friends of smokers increases the likelihood of becoming a smoker (O'Loughlin et al 1998; Powell et al 2005), while discouragement from the social network is negatively associated with smoking status (Hofstetter et al 2007).…”

Propensity for social interaction predicts nicotine‐reinforced behaviors in outbred rats

“…In spite of these negative effects, approximately 40% of teenagers who experiment with cigarettes become regular smokers (Hofstetter et al ). One critical factor that has large influence on smoking initiation is social environment (Hu et al ; Schepis & Rao ; White et al ). In the socially acquired nicotine SA model, social transmission of the nicotine‐associated odor cue enabled the transition from nicotine‐conditioned taste aversion to stable SA (Chen et al ).…”

“…Social environment is also critical for smoking. In fact, peer smoking is one of the strongest predictors of smoking initiation (Greenlund et al ; White et al ). Using olfactogustatory (OG) stimuli as the contingent sensory cue for intravenous nicotine delivery, we demonstrated the role of social learning in nicotine SA (Chen et al ).…”

Drinking Motives in Female Smokers: Factor Structure, Alcohol Dependence, and Genetic Influences

“…In contrast, regular smokers reported significantly lower conformity motive scores compared to nonregular smokers, suggesting that regular smokers were less motivated to consume alcohol to avoid social consequences such as peer pressure to drink, not being ''liked'' and feeling ''left out.'' There is evidence that adolescents who smoke are more likely to select friends who smoke (Engels et al, 1997), and there is a robust link between the smoking behavior of one's peers and current and future smoking behavior among adolescents and young adults (Ennett et al, 2008;Hoffman et al, 2006;Kobus, 2003;White et al, 2008). Coupled with evidence for peer influences on smoking in women (Rose et al, 1996), one explanation for our finding of lower conformity scores in regular smokers is that smoking behaviors, not alcohol consumption, might be the primary route for smokers to feel amalgamated with their social networks.…”