The study provides novel evidence that expectations of smoking reward facilitate smoking uptake among depressed adolescents. Higher depression symptoms across mid to late adolescence predicted a 17% increase in smoking reward expectations, which in turn predicted a 23% increase in the odds of smoking progression. These findings offer an initial glimpse at reward-related processes that may occur early in the smoking acquisition process for youth with elevated depression symptoms. Expectations that smoking offers several benefits highlight depressed adolescents who are vulnerable to smoking. These expectations of reward are an important mechanism to target in smoking prevention programs for depressed youth.
The influence of smoking reward expectations on adolescent smoking escalation has been largely unexplored. Research has shown that expectations that smoking would remove displeasure, such as reducing negative affect, predicts smoking escalation in adolescents (Heinz et al., 2010
). The present study adds to the sparse literature by showing that expectations that smoking will provide pleasure, motivates smoking among depressed youth. Expectations that smoking confers rewards (e.g., enjoyable, something to do when bored, stay thin) increases the likellihood that depressed adolescents will choose to smoke. As nicotine can ameliorate the affective and reward processing deficits associated with depression (Barr et al., 2008
; Gilbert et al., 2008
; Kenny and Markou, 2006
; Spring et al., 2008
; Warburton and Mancuso, 1998
), and impact neurocognitive processes that are typicaaly diminished in depression (Evans and Drobes, 2009
; Gilbert et al., 2008
; Heishman et al., 2010
), these adolescents may indeed learn that smoking is rewarding. Thus, their smoking experience may then serve to validate their expectations.
Converging research supports the notion that depressed adolescents may find smoking more rewarding than nondepressed adolescents. Depression-prone smokers have greater smoking-induced dopamine release than smokers not prone to depression (Brody et al., 2009
). It is possible that nicotine’s primary reinforcing effects are amplified for youth either prone to depression or during periods of elevated depression symptoms. In addition, individuals prone to depression tend to have fewer reinforcers (Jacobson et al., 1996
; Lewinsohn and Amenson, 1978
; MacPhillamy and Lewinsohn, 1974
) and derive less reward from natural reinforcers in their environment (Forbes et al., 2009
; Shankman et al., 2007
; Wichers et al., 2009
). Recent research has shown that declines in the frequency and enjoyability of typical reinforcers leads to smoking escalation among young adults with elevated depression symptoms (Audrain-McGovern et al., 2011
). Pre-clinical models suggest that nicotine potentiates reward from available reinforcers by increasing the sensitivity of brain reward systems or the ability to derive pleasure from available reinforcers (Kenny and Markou, 2006
). Thus, nicotine has relevant secondary reinforcing effects by increasing the pleasure derived from reinforcers in the context of limited reinforcers (Spring et al., 2008
). Further investigation of reward related mechanisms may identify unique biological and behavioral functions of smoking and nicotine in adolescents with elevated depression symptoms.
From a clinical perspective, these findings provide further support for mid to late adolescence as an etiologically important developmental period for the comorbidity between adolescent smoking and depression. On average, about 25% of adolescents had clinically significant levels of depression symptoms across three years. Assessing smoking reward expectations in this subgroup may identify those adolescents at risk for smoking. As almost 30% - 60% of adults entering smoking cessation programs have a history of major depression (Cinciripini et al., 2005
; Ginsberg et al., 1995
; Glassman et al., 1988
; Haas et al., 2004
) and 50% have elevated depression symptoms (Cinciripini et al., 2005
; Lerman et al., 1996
; Niaura et al., 2001
), addressing this issue during adolescence could have a significant impact on the excess smoking burden incurred by individuals prone to depression. Addressing alternative ways to meet the rewards (e.g., source of pleasure, something to do) expected of smoking may prove to be an important part of adolescent smoking prevention and cessation interventions for depressed youth. Smoking reward expectations may also highlight areas where a depressed adolescent has weak skills such that smoking is perceived as a helpful option, but in reality is an ineffective solution (e.g., a way to handle problems). Although relatively less attention has been paid to these features in adolescent smoking prevention programs, these components may be critical to preventing smoking uptake among youth who have elevated depression symptoms.
The present study also considered the possibility that smoking influenced the development of depression symptoms through smoking reward expectations (e.g., reciprocal directional effect). The rate of smoking progression was associated with a doubling in the rate of change in smoking expectations over time, which translated to a 10% increase in smoking reward expectations for every six months that passed. Further, increases in smoking expectations were associated with a 15% increase in the odds of having high depression across time. Thus, smoking uptake shaped and indeed increased smoking expectations across time. Of note, as smoking expectations increased so did the likelihood of depression. Although the indirect effect failed more stringent tests of significance, the findings raise questions about whether unrealistic or unmet smoking reward expectations (e.g., way to handle problems, a method to stay thin) could contribute to the development of depression in adolescent smokers. This would certainly be consistent with social and cognitive vulnerability models of the depression (Prinstein and Aikins, 2004
; Prinstein et al., 2005
). Addressing alternative and effective ways to meet the rewards expected of smoking and educating youth on unrealistic expectations for smoking may impact adolescent smoking irrespective of the directional pathway.
While this is the first study to examine the link between depression symptoms, smoking reward expectations and adolescent smoking progression, the study has strengths along with potential limitations. Study strengths include an excellent participation rate, a large sample, repeated measures of key variables, smaller measurement intervals than previous adolescent smoking studies, and control for many confounding influences in the statistical models. Although the clinical significance of depression symptoms or “subthreshold depression” among adolescents has been well established (Lewinsohn et al., 2000
), we are not able to measure the extent of depression as diagnostic assessments were not completed. Higher levels of depression as measured by the CES-D may have been reflective of clinical episodes rather than subclinical depression symptoms.
It is also possible that expectations that smoking will reduce displeasure, such as negative mood influences smoking among depressed youth. Unfortunately, we did not measure these expectations in the present study. A broader understanding of the expectations that depressed adolescents have for smoking may help highlight other smoking prevention intervention targets. Finally, we controlled for many confounding influences at baseline, but time-varying influences and the role of psychological comorbidity were not considered in the already complex model. Peer smoking effects, externalizing and anxiety symptoms stand out as important variables to consider across time.
Although not necessarily a limitation, it is important to point out that not all depressed adolescents initiated or progressed in smoking. It is possible that those adolescents who have more consistently elevated symptoms are those most at risk for smoking progression. Identifying which depressed adolescents find smoking rewarding may pin-point those adolescents most vulnerable to progressing to regular smoking and illuminate novel nicotine/smoking actions in this vulnerable population. Our model accounted for 46% of the variance in smoking progression emphasizing that other mechanism warrant investigation.
In summary, this study highlights a novel connection between high depression symptoms, expectations of smoking reward and adolescent smoking progression. As such, this study represents a shift away from research focusing primarily on the role of negative affect in adolescent smoking to reward-related processes. Further research is warranted to increase our understanding of how smoking and nicotine affect adolescents prone to depression, ultimately informing efficacious smoking and possibly depression treatments for this population. Earlier interventions may mitigate the comorbidity that appears to track well into adulthood thereby decreasing the disproportionate smoking attributable morbidity and mortality in a population prone to depression (Prochaska, 2010