Background
Menthol comprises nearly a third of the tobacco market. It’s minty taste and cooling and anesthetizing properties have been posited to reduce the harshness of smoke inhalation, may contribute to tobacco use and smoking initiation in young people [
1‐
4], and may prevent tobacco users from quitting [
5‐
7]. While recent data show decreases in the prevalence of non-menthol cigarette smoking [
6,
8] there has been an increase in menthol cigarette use in young adults during this same time period [
9]. Menthol has been proposed as an important factor in the transition from initiation to regular tobacco use during young adulthood [
3,
4].
Menthol may increase the addictive potential of tobacco use via multiple mechanisms, including biological, genetic, environmental, and dispositional [
10‐
16]. Menthol tobacco use may be maintained through its association with positive, pleasurable, and other hedonistic responses to nicotine. This may attract new users [
3,
4] and facilitate greater ingestion of harmful tobacco constituents [
11]. Further, the highly salient positive sensory properties of menthol may enhance the overall rewarding effects of nicotine reinforcement [
12,
17], thereby strengthening the uptake of cigarette or other nicotine-containing tobacco products among emergent users. This then enhances the addiction potential of menthol tobacco products, and may hinder success at quitting later on [
18].
Psychiatric distress, including depression and anxiety, is linked to tobacco use, greater nicotine dependence, smoking persistence, and poor smoking cessation outcomes [
19‐
22]. Similarly, menthol cigarette smoking has consistently been associated with more severe nicotine dependence [
23] and lower quit rate success than non-menthol smokers [
24‐
26]. A paucity of published research, however, has focused on the link between mental health factors and menthol cigarette and other tobacco product use in young adult populations, despite the exceedingly high rates of menthol tobacco use in this age group. Of the few studies published linking menthol use to mental health, findings show that the prevalence of menthol cigarette smoking is high among those with severe psychological distress compared to those without [
11,
27,
28] and that menthol smokers report worse general mental health than non-menthol smokers [
29,
30]. One recent population-based study of young adults found that menthol cigarette smoking was correlated with marijuana use and binge drinking [
31], two health-risk behaviors that are also robustly linked to psychiatric distress [
32‐
37]. One explanation for the association between menthol cigarette smoking and mental health problems could be due to the cooling sensation of menthol, which has a mildly arousing and stimulating effect [
38], and may dampen frequent or chronic dysphoric mood often present with certain mental illnesses. Indeed, prior research shows that menthol cigarettes are used to enhance drug-related high and to sustain euphoric mood states [
39]. Other research suggests that the nicotine in tobacco, more generally, is used to self-medicate mood disorders [
36,
40]. If this was the case, then menthol tobacco use would not be differentially associated with mental health problems, compared to non-menthol tobacco use. Taken together, the stimulating and arousing properties of menthol in nicotine-containing tobacco products might be attractive to young adults with mental illnesses, perhaps to self-medicate and cope with negative mood states. If menthol increases the subjective effects of nicotine on mood improvement, one might expect greater uptake of menthol tobacco products in young adults with mood problems than those without.
In sum, mental health problems and menthol cigarette smoking have been robustly linked to smoking persistence, nicotine dependence, and poor smoking cessation rates [
20,
41]. Further, a high prevalence of menthol cigarette use has been documented among young adult tobacco users [
8,
42,
43]. As such, it would be important to determine whether menthol tobacco use is associated with increased mental health problems in this age group. Such findings may explain, in part, why menthol cigarette use is correlated with smoking initiation and progression in young people – it is being used to self-medicate or cope with stress and emotional problems. Further, because young adults use a variety of tobacco products, not just cigarettes [
44], it would be important to examine the association of all types of menthol tobacco products, beyond cigarettes, to mental health problems. This study used a national sample of over 9600 young adults to examine the prevalence of depression and anxiety as a function of menthol tobacco product use, after adjusting for demographic and psychosocial risk factors known to impact both mental health and tobacco use (i.e., alcohol, drug use). We hypothesized that menthol tobacco use would be associated with increased mental health risk, above and beyond the impact of other robust mental health and tobacco use risk factors. Additionally, because this study examines the association of menthol tobacco use with depression and anxiety, above and beyond other mental health and tobacco use risk factors, we also describe the links between these risk factors and the outcomes of interest, to situate our primary hypothesis in context. Such findings would suggest that removal of menthol tobacco products from the tobacco marketplace may prevent initiation and progression to regular use among particularly vulnerable groups of incipient users.
Discussion
Studies linking menthol tobacco use, beyond just cigarette smoking, to higher rates of depression/anxiety in young adults are scant. This study sought to uncover whether menthol tobacco-using young adults show certain mental health vulnerabilities relative to non-menthol users, after controlling for other covariates known to impact both mental health and tobacco use in this age group.
Bivariate analyses showed that current menthol-flavored tobacco users reported anxiety and depression at a higher prevalence compared to the full sample and to non-menthol tobacco users. Consistent with prior research, women, those with lower educational and financial means, and those currently using tobacco and other drugs were more likely to report anxiety and depression [
64,
65]. Race was differentially associated with depression and anxiety, such that non-White respondents were most likely to report depression; however race was unrelated to anxiety. Alcohol use was not associated with either depression or anxiety, which we would not expect based on prior [
34,
66]. Our findings may have been due to our assessment of alcohol use, which measured only general consumption in the past 30-days, but not consequences of use or heavy drinking; alcohol-related problems or indices of risky drinking behavior may be better predictors of mental health problems.
Stepwise modified Poisson regression models revealed that the odds of reporting anxiety and depression were nearly two and half times greater among those not meeting basic financial needs, relative to those meeting basic needs with some additional money left over. Further those currently using other drugs, such as cocaine, methamphetamine, or ecstasy, had the highest risk of anxiety and depression; nearly three times higher (for both outcomes) relative to respondents not using other drugs. Lastly, as we predicted, menthol tobacco use was associated with elevated risk for both mental health outcomes, after controlling for a number of other risk factors. This suggests there is something unique about menthol in tobacco products that links it to affective vulnerability. Such findings are concerning given the robust association between psychiatric distress, particularly depression, with more severe nicotine dependence, smoking persistence, and higher rates of smoking relapse among adult tobacco users [
20,
67‐
70]. Thus, mental health may be one factor explaining why menthol smokers have worse cessation outcomes and greater nicotine dependence relative to non-menthol smokers in some studies [
7]. This has important implications for incipient tobacco users with depression or anxiety. These individuals may start their tobacco use “careers” with menthol, but may find it exceedingly difficult to quit in later years because of the subjective rewarding effects of menthol [
16], as well as the desire to self-medicate negative mood symptoms with nicotine [
36,
40].
There could be several reasons why menthol is linked to mental health. First, the stimulating properties of nicotine, coupled with the positive sensory aspects of menthol, may relieve the negative moods and other aversive symptoms (i.e., weight gain, irritability, fatigue) that are common among individuals with depression or anxiety [
36,
40]. If nicotine was the only mood-enhancing factor of tobacco use, then we would not have found differences between menthol and non-menthol tobacco users. These findings add to the literature, and suggest that menthol tobacco has distinct properties that drives its use among certain groups of users, and which may lead to more persistent use later on [
12,
16,
17,
71]. Alternatively, individuals with an underlying vulnerability toward a variety of health-risk behaviors may self-select to use menthol tobacco. This may be because menthol flavoring is offered in a variety of different tobacco products [
43] and vulnerable young adults are likely to try many substances of abuse, not just cigarettes [
72]. A third reason could be that menthol is more likely to be sold in neighborhoods where socially and economically disadvantaged individuals reside, including those with mental health problems. For example, Young-Wolff and colleagues [
27] found that tobacco retailer densities were twice as high in areas occupied by smokers with serious mental illness relative to the general population. Our findings showed that individuals with lower financial means and educational attainment were prone to mental health problems, and thus, the link between menthol use and mental health in young adults may be partially explained by tobacco marketing toward these lower income individuals. We did not assess the impact of tobacco marketing, nor neighborhood composition in this study.
There were several limitations of this study. First, we cannot conclude that menthol causes mental health problems due to the cross-sectional nature of the analyses. Similarly, we did not examine product switching, or the case in which someone could have been a menthol user at one time point, but no longer a menthol user at a subsequent time point; although prior studies indicate this is not common [
1,
73]. Follow-up studies can examine whether age of menthol initiation predicts subsequent onset or progression of anxiety and depression. Second, this was a secondary analysis and we were limited to the measurement items within the dataset. Other factors not currently measured, such as neighborhood composition and social network factors, may impact rates of menthol use and mental health. Third, rates of anxiety and depression in the present study were higher than those reported in other national samples [
21,
22]. This is likely due to the sensitivity of our 2-item measures. A more in-depth clinical assessment of depression, anxiety, and substance use features may be warranted [
74]. Fourth, this study uses an existing online panel to recruit a large, national cohort of young adults. Although African American and Hispanic young adults were oversampled to ensure sufficient sample sizes, our sample may not be representative of the national population of young adults. Finally, we did not examine the impact of individual tobacco products (i.e.,e-cigarettes, LCCs, hookah) on mental health outcomes due to small sample sizes. Given the rising popularity of flavored tobacco use in young people [
43], future work should examine product-specific links between menthol flavoring and mental health in this age group.
This study has several strengths. We are not aware of any national studies that have examined the link of menthol tobacco use, beyond menthol cigarette use, and mental health in young people. Of the two large-scale studies that have been published, both focused on adult populations and used either a general measure of psychiatric distress [
28] or a crude measurement of well-being [
30]. Further, both focused exclusively on menthol cigarette use, not tobacco use more generally. Examining a broad set of menthol tobacco product use, not just cigarette smoking, is particularly relevant to young people. Young adults have the highest rates of tobacco product use (cigarette and non-cigarette products) relative to any other age group and are highly likely to use a variety of different types of tobacco products [
44]. Further, the use of flavored tobacco products, including menthol, is particularly prevalent in this age group [
43].
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
AC, AJ, and AV conceived of the study and oversaw the data analysis. AJ conducted the data analyses. AC and AJ drafted the manuscript. JR, EH, AJ, and AV provided input on the manuscript drafts. All authors read and approved the final manuscript.