The recent increase of smoking among teens (1991-1997) is particularly worrying because research has shown that the earlier the onset of smoking, the mote severe nicotine addiction is likely to be. In fact, long-term nicotine dependence has resulted primarily from the initiation of tobacco use during adolescence. Nicotine is generally the first drug used by young people who enter a sequence of drug use including tobacco, alcohol, marijuana and other drugs of abuse.

Existing epidemiological data illustrate the severity of smoking initiation and maintenance in adolescents, and the formidable challenges that prevention and treatment present. Although the majority of quitters are adults, a significant number of teenage smokers attempt to quit and fail and about 40 percent of teen smokers express interest in some form of treatment for tobacco dependence. Thus, further empirical investigation in the areas of adolescent tobacco addiction and treatment are warranted.

Risk factors

Many factors influence the predilection for cigarette smoking, including psychological, biological and environmental factors, and regulation of cigarette sales. Socially and developmentally, smoking can become a way for adolescents to instantly appear independent and mature while fitting in with peers who smoke. According to recent research, experimenting with cigarettes and sex, being uncertain about smoking in the future, reporting having been drunk, having a boyfriend or girlfriend, and believing teachers and friends would not mind if they smoked are some of the strongest predictors of smoking. Important correlates of transition from trail to occasional use include friends' smoking and approval, cigarettes offered by friends, smoking intentions, and alcohol and marijuana use. Significant predictors of the transition from occasional to regular use include only parental smoking and family conflicts.

While little has been reported regarding psychiatric morbidity and how it might impact the adolescent's decision to start and/or continue to smoke, an association of tobacco smoking with depression and anxiety has been demonstrated in adolescents. It has also been reported that ADHD, particularly comorbid ADHD (comorbid with CD, major depression or anxiety disorders), and early initiation of cigarette smoking are associated. Furthermore, the presence of ADHD and major depression has been shown to predict the severity of nicotine dependence in teenagers with substance use disorders.

Other factors contributing to nicotine dependence in adult smokers have yet to be closely examined in adolescent smokers. It is not known whether performance-enhancing effects of nicotine are present in adolescents, and if so, whether they play a role in the initiation or maintenance of cigarette smoking in this age group. Gender factors may also contribute to adolescent smoking dependence. This is suggested by the recent rise in tobacco smoking among adolescent females, which has been shown to be associated with dieting and weight concerns.

The overall impact of regulatory efforts implemented by the FDA in 1997 to reduce adolescents' access to cigarettes remains undetermined. However, an increase in unit sales price should decrease purchases and consumption. Paradoxically, rates of adolescent onset of smoking have been rising despite increasing efforts to curb adolescent access to tobacco.

Although adolescences can access treatment as emancipated minors in some states, they cannot access research trials without parental/guardian involvement. This constraint can bias and reduce recruitment in controlled treatment studies.

Characteristics of nicotine use in adolescents

The onset of and the first self-generated efforts to control tobacco addiction occur most typically during adolescence. Although other subphases have been described, three important clinical phases precede tobacco dependence: trial, occasional use and daily use.

No formal criteria have been adopted to define adolescent nicotine dependence, although several studies are currently in progress. More research is needed to evaluate how various versions of the Fagerstorm (rapid paper and pencil test) and DSM criteria could apply to youth. Many adolescents are in the progress of developing dependence to nicotine and tobacco, whereas the majority of adults have been dependent for a number of years or decades. Smoking patterns are also more variable in rate and frequency in adolescents compared to adults.

Treatment interventions for adolescent smoking

Overall, adolescent smoking cessation programs have yielded low success rates. Compounding this, both recruiting and retaining adolescents in formal cessation programs are challenging. Various types of treatment interventions have been deployed with regards to methodological design, theoretical underpinnings, modalities and settings, length of intervention, age groups, entry criteria, and follow up treatment. Major weaknesses of the studies conducted to date include: weak designs, lack of biochemical validation, underreporting of mean reduction of tobacco use, and a general lack of appropriate control groups. The paucity of generalizable data from controlled studies constitutes an additional barrier to the adoption of suitable and specific treatment modalities for adolescent smoking cessation by the health care community.

In recent studies, teenagers' smoking frequency was inversely related to quitting.

To help tailor cessation programs for youth, factors that could facilitate quitting have been examined. Further characterization of how these factors might enhance tobacco cassation within a context of image, self-efficacy and adoption of long-term healthy behaviors is of specific relevance.

Pharmacological treatment

A lack of controlled studies of pharmacological interventions is also evident. In addition to the lack of controlled studies, insufficient data exist to guide the generalized application of any pharmacotherapies, as many issues pertaining to indication (level of dependence), compliance and tolerability remain unresolved. Tobacco-dependent adolescents experience the same degree and types of withdrawal symptoms as tobacco-dependent adults, and relapse for some of the same reasons as adults.

Safety, low abuse liability and efficacy of nicotine replacement therapy (NRT) - e.g., transdermal patches and gum - for adults have been well documented. However, its effects in adolescences have not well studied. Currently, only two open-label studies of the use of NRT in adolescents have been published. Preliminary data indicate that the adolescent side-effect profile for the nicotine patch is similar to that of adults.

Recent findings support the efficacy of the antidepressant bupropion to enhance adult smoking cessation, regardless of depression history. Thus, bupropion might be another valuable therapeutic agent for a subgroup of tobacco-dependent youth.

Combined treatment

Combined (biopsychosocial) interventions that have been successful in adults may also be indicated for youth. Behavioral support, which can approximately double the efficacy rates of pharmacotherapy in adults, has been limited in previous studies of pharmacological interventions in adolescent smokers.

Reduction as treatment outcome

In the first open label study using transdermal nicotine therapy, the decrease in cigarette consumption seen at week four was sustained until week eight for those adolescents who completed treatment.

The increased severity of tobacco dependence and morbidity associated with earlier age of onset of tobacco smoking underlines the importance of slowing, if not halting, the progression from occasional use of tobacco to dependence. Thus, if it is shown that overall reduction of smoke intake decreases morbidity and mortality, then lower smoking rates could become a valid transitional treatment goal on a continuum toward eventual cessation. However, questions remain about whether harm- or exposure-reduction approaches undermine prevention and cessation efforts.

Conclusion

Clearly, additional adolescent tobacco-related epidemiological and clinical data (including medication trials) are critically needed. For adolescents who seek treatment, appropriate combined and age-specific modalities - few of which have been adequately tested - should be utilized while recognizing the importance of socio-environmental influences of peer and family settings.

[The author would like to acknowledge Joanna Hills for her contribution to this article.]