The present study examined the association between pubertal timing and age at first cigarette in a large sample of White and Black adolescent females. When Black and White groups were examined separately, early pubertal timing was associated with earlier age of smoking initiation in Black girls only. This was counter to expectations as most of the literature focuses on White samples and the findings between early timing and substance use are well supported (Dick et al., 2000
; Lanza & Collins, 2002
; Westling et al., 2008
). However, when race was tested as a moderator, there was not a significant interaction between racial group and pubertal timing, but there was a main effect of pubertal timing. Most studies have found that only early timing is associated with increased substance use. For example, girls with early puberty reported a younger age of first cigarette than those with later puberty (Wilson et al., 1994
) and were 1.5 times more likely to smoke (Bratberg, Nilsen, Holmen, & Vatten, 2005
). However, we found that early and on-time groups were at increased risk for early smoking initiation compared with the late timing group.
Although previous research has demonstrated that White adolescents initiate smoking earlier, smoke more, and progress to becoming regular smokers more rapidly than Black adolescents (Harrell et al., 1998
; Kandel, Kiros, Schaffran, & Hu, 2004
), our study shows that a racial disparity may not exist when assessing the effect of pubertal timing on smoking behavior. Late timing for both Whites and Blacks seems to be protective against early smoking initiation. Smoking behavior in adolescents, and especially early age at initiation, is particularly important when examining long-term smoking and health consequences. Youth who begin smoking in lower grades are more likely to be adult smokers (Chassin, Presson, Sherman, & Edwards, 1990
). Additionally, age of smoking initiation is a significant factor for failure in cessation attempts (Khuder, Dayal, & Mutgi, 1999
). These findings point to targeting early and on-time maturers for smoking prevention programs in adolescence. Furthermore, because pubertal timing is occurring earlier for contemporary adolescents than in the past, targeting early and on-time maturers at younger ages may be important.
There are several possible explanations for the differences between our results and other studies. First, variability in how pubertal timing was determined across the studies may yield differences in timing classifications. We used age at menarche, which is an event later in puberty, whereas other studies used ratings of secondary sexual characteristics (e.g., breast and pubic hair development). Although menarche and secondary sexual characteristics are associated, the data suggest only a moderate correlation between the two, thus introducing a potential source of error (Biro et al., 2006
). Second, the majority of the participants were in mid- to late adolescence when it becomes more likely that they will have tried smoking. Several studies have found evidence of a “catch-up” effect when assessing older adolescents. Specifically, late maturing females between 16 and 18.5 years caught up to their early and on-time maturing peers in their alcohol use (Dick et al., 2000
). Thus, in early adolescence, early timing may be important in predicting substance use, while later in adolescence, girls with on-time development may be using substances as much as the early maturers. It is also possible that in late adolescence, pubertal timing effects may be negligible (Stattin & Magnusson, 1990
) with the host of other influences that may be more salient for substance use. However, the age at onset of cigarette use is still important as it influences prolonged substance use into adulthood (Faulkner, Escobedo, Zhu, Chrismon, & Merritt, 1996
; Grant & Dawson, 1997
One limitation of this study may be that our dependent variable was age of first cigarette, which may not necessarily reflect continued smoking. An individual may try a cigarette but then not smoke ever again. However, in the present sample, 68% of those who reported an age at first cigarette have continued to smoke. Thus, like other studies (Lewinsohn et al., 1999
; Sung et al., 2004
), we find that age at first cigarette is an important consideration when assessing future smoking, and intervening early is essential for prevention of long-tem health problems.
A second limitation is that self-report was used for age at menarche and age at first cigarette. Although it is impossible to check the veracity of the reported ages, it is probable that for these events, the adolescent is the most accurate reporter. When our study is completed, we will be able to assess the reliability of reports across time for the age of smoking initiation and age at menarche. The number of girls who had not yet smoked might be viewed as a limitation; however, survival analysis accommodates large amounts of censored data, utilizing the maximum amount of available information from censored data for analysis (Singer & Willett, 1991
An additional limitation may be the sample size for this study. Due to the nature of the pubertal timing variable, there will inherently be more participants in the on-time group than in the early or late groups. However, many studies have used this variable with similar distributions and sample sizes to the current study, thus our confidence is increased. Additionally, because this was a secondary data analysis, we may have limited statistical power, particularly in examining interaction terms. The nonsignificant interaction effect may be due to difficulties with unequal cell sizes and creating categorical variables from continuous ones as well as lack of power (Aguinis, Boik, & Pierce, 2001
; Frazier, Tix, & Barron, 2004
). However, we feel confident that the cell sizes are adequate for the analyses, and the findings are valid and show some novel associations between pubertal timing, smoking onset, and race.
Other factors that were not measured in this study can influence smoking behavior, such as early dating and parental monitoring (Fidler, West, Jarvis, & Wardle, 2006
; Westling et al., 2008
). However, the inclusion of parent and friends smoking did account for two large influences on smoking. Other studies found that friend smoking was related to smoking initiation among Whites but not Blacks (Headen, Bauman, Deane, & Koch, 1991
) and parent smoking contributed to the onset of daily smoking in their teenagers (Hill, Hawkins, Catalano, Abbott, & Guo, 2005
). In the present study, parent smoking was related to age at first cigarette with having a parent who smokes increasing the risk by 1.6 times. Thus, to reduce the risk for daily smoking in adolescents, it may be important to encourage parents to stop or reduce smoking.
Cross-sectional studies have inherent limitations in being unable to unravel causal pathways. Additionally, because we have not observed all the participants through the period of highest risk for smoking initiation, we lose some information about those defined as censored. Some of the girls who enrolled as nonsmokers at the time of the assessment may eventually initiate smoking, but we have no way of knowing when that critical age may be for every individual. Several studies have examined smoking initiation data using survival analysis, and they provide useful information about the risks (Andreeva, Krasovsky, & Semenova, 2007
; Chen, Unger, & Johnson, 1999
). One study found that after age 14, the risk of new smoking initiation decreases (Unger & Chen, 1999
). The majority of the sample is older than 14 years, and thus, we may be more certain that we are capturing the accurate risk model for smoking initiation. In the future, we can examine the smoking onset age for all girls up to age 17 and assess the reliability of age at smoking onset from the subsequent yearly visits.
Overall, our results indicate that early and on-time pubertal development increases the risk for early smoking onset in adolescent girls. Contrary to expectations, we did not find racial differences in this association, indicating that late timing may be protective for both White and Black girls. Our study shows that a racial disparity may not exist when assessing the effect of pubertal timing on smoking behavior for White and Black adolescents. However, possible differences should be examined for other racial minority groups. Additionally, this result provides evidence for the importance of assessing puberty in studies of substance use. While there are clearly multiple factors that contribute to the etiology and maintenance of substance use, we show that omitting puberty is overlooking a substantial influence on early substance use. Future models should aim to incorporate these numerous influences, including a reliable measure of puberty so that we can better understand these complex relationships and work toward the prevention of prolonged substance use.