"During early adolescence, a single nicotine injection (0.5 mg/kg) induced significant conditioned place preference (CPP). In contrast, during late adolescence or adulthood, nicotine did not induce CPP after either one or four conditioning trials. Initial locomotor responses to acute nicotine administration during the first conditioning trial also differed with age, with no effect at P28, but substantial inhibitory responses at all doses studied (0.125-0.5 mg/kg) at later ages. Although not differing in their initial locomotor response to nicotine, there was a significantly greater tolerance/sensitization during the second and subsequent drug exposures in late adolescents than in adults."

(Source:  James D. Belluzzi, Alex G. Lee, Heather S. Oliff and Frances M. Leslie, "Age-dependent effects of nicotine on locomotor activity and conditioned place preference in rats," Psychopharmacology, Issue: Online First, 22 January 2004, DOI: 10.1007/s00213-003-1758-6; http://springerlink.metapress.com/app/home/contribution.asp?wasp=lp3efwturk3yp877tmdq&referrer=parent&backto=issue,142,162;journal,1,178;linkingpublicationresults,1:100390,1.) 

"According to the Centers for Disease Control, 80 percent of adult smokers start smoking as adolescents. While there are multiple reasons why teens try smoking, this study supports earlier findings identifying biological reasons for cigarette addiction. These earlier studies have shown that teens develop symptoms of dependence after minimal tobacco exposure and that those who smoke daily as teens will more likely have difficulty quitting than those who start as adults."

(Source:  "UCI tobacco research center study suggests first exposure to nicotine may change adolescents' brains and behavior," University of California, Irvine, May 13, 2004; http://today.uci.edu/news/release_detail.asp?key=1153.)

The international ubiquity of divorce lawyers makes business much easier for American tobacco companies trying to market their slow poison among young people abroad.  Quantifying just how much family disintegration multiplies adolescent customers for tobacco, a new study by public-health scholars at the University of Edinburgh carefully examines the relationship between family structure and tobacco use among fifteen-year-old adolescents in seven European countries: Austria, Denmark, Finland, Germany, Norway, Scotland, and Wales. 

Relying on World Health Organization data, the Edinburgh scholars find that "smoking among 15-year-olds was significantly related to family structure in all countries."  More specifically, "young people in intact families were less likely to be daily smokers than those in lone-parent families, who in turn were less likely to smoke than young people in stepfamilies."  The prevalence of daily smoking among adolescents in single-parent families ran roughly half again higher than that observed in intact families; however, the prevalence of daily smoking among adolescents in step-families in most countries ran double that among adolescents in intact families. 

Closer scrutiny of the data suggests that teens in non-intact families smoke more than peers in intact families in part because they are more likely to live with a parent or other person who smokes and are less likely to live in relative affluence.  But even after statistically accounting for the increased likelihood that teens in single-parent families will live with a smoking parent or other adult and the decreased likelihood that they will live in affluence, the researchers found "higher odds ratios for adolescent smoking in lone-parent families compared to intact families, [though] this only reached [statistical] significance level in Austria (O[dds]R[atio] - 1.80) and Finland (O[dds]R[atio]) - 1.99)." And even with the statistical controls in place for household smoking and relative affluence, the researchers discerned "a strong independent association between being a [teenage] smoker and being in a stepfamily."  

The strong independent linkage between adolescent smoking and stepfamilies, which emerged in every country except Wales, caught the researchers' attention as "the most striking finding of their investigation."  Indeed, in four out of the seven countries investigated, "living in a stepfamily increased the likelihood of being a [teenage] smoker more than any other factor." 

In trying to account for the high level of adolescent smoking observed in stepfamilies, the Edinburgh scholars cite a 1997 study in the United States which concluded that "family structure acted indirectly on smoking through an association with lower levels of attachment in non-intact families."  They also speculate that an increased likelihood of teen smoking in stepfamilies may be the outcome if an adolescent "refuses to recognize the authority of the step-parent, or if the stepparent is reluctant to assume parental authority in dealing with problems relating to his or her stepchildren."  The researchers wonder if stepfamily teens are not inclined to take up smoking if they "spend their time in two different families" and consequently experience "a lack of clarity or disagreement between the two households on certain matters, including smoking."   The researchers further conjecture that adolescents in stepfamilies often take up smoking because "divorced parents are less likely to monitor and discipline their children than those in intact families."