The link between tobacco use and mental health issues, such as depression, is well-established (CDC, 2022) and has numerous public health implications, especially given the high prevalence of tobacco use (Cornelius et al., 2022) and its personal and societal costs (Hall & Doran, 2016). The prevalence of depression among current smokers is twice as high as that of former or never smokers (Goodwin et al., 2017). In addition, individuals with depression are less likely to quit smoking than those without depression (Weinberger et al., 2017). Individuals who abstain from smoking have been shown to experience considerable improvement in their depression (Stepankova et al., 2017). Furthermore, because quitting smoking is extremely challenging and individuals who smoke try numerous times to quit (Chaiton et al., 2016, Pipe et al., 2022), it is important to understand factors that may affect their ability to remain abstinent.

Smoking self-efficacy (Velicer et al.,1990) is defined as confidence in one’s ability to abstain from smoking in high-risk situations, and is often measured by both intrinsic and extrinsic self-efficacy (Rajani et al., 2021). Importantly, depressed adults tend to experience lower smoking self-efficacy (Wang et al., 2022), and individuals with lower smoking self-efficacy and greater depressive symptoms are less likely to recover from a smoking relapse (Muench et al., 2020).

Studies have found that improving self-efficacy reduces return to use (Elshatarat et al., 2016, Gallus et al., 2023, Klemperer et al., 2020) . Though less frequently examined, there is also evidence to suggest a bidirectional relation between self-efficacy and abstinence, in that abstinence or reducing one’s number of cigarettes per day may lead to increased self-efficacy to abstain, for those interested in quitting (Perkins, Parzynski, Mercincavage, Conklin, & Fonte, 2012). This process may occur because smokers’ cognitive responses to their smoking reduction increases their confidence in further reducing or quitting (i.e., increases self-efficacy). Previous research has shown that smokers who reduce the number of daily cigarettes smoked are more likely to attempt and actually achieve cessation (Begh et al., 2015). Indeed, the number of cigarettes smoked and having at least one quit attempt in the past year have all been associated with higher self-efficacy to quit (Al Thani et al., 2022). Thus, it is imperative to examine how quit attempts affect smoking self-efficacy, as it can improve later smoking cessation outcomes.

To date, despite sex differences in smoking behaviors and cessation, the extent to which male and females differ in changes in self-efficacy resulting from a smoking quit attempt has yet to be examined. Importantly, current and former female smokers are at significantly higher risk of depression than male smokers (McKee and McRae-Clark, 2022, Verplaetse et al., 2016), and being assigned female at birth (AFAB) vs. assigned male at birth (AMAB) confers a greater negative affect of depression on self-efficacy (Park and Lee, 2023, Santos et al., 2018). Additionally, female smokers have more difficulty maintaining long-term abstinence than male smokers (Smith et al., 2016). The findings in the literature on why said sex differences in smoking cessation outcomes exist are mixed. Sex differences in smoking cessation may relate to differing influences of psychological versus environmental barriers to quitting (Davis & Jason, 2005, Ma et al., 2020). For example, for those assigned female at birth (AFAB), psychological factors (e.g., negative emotions and experiences of stress) are more likely to precipitate return to use, compared to those assigned male at birth (AMAB), for whom environmental factors (e.g., smoking in social gatherings or with alcohol) have been found to be more impactful (Dieleman et al., 2021). To summarize, although to our knowledge, no prior research has examined sex differences in the relation between abstinence and self-efficacy, there is considerable evidence that the processes of reducing substance use and improving self-efficacy may show sex differences.

Current research shows that smokers with depression have lower smoking self-efficacy, and that AFAB smokers (vs. AMAB smokers) have lower self-efficacy and greater difficulty quitting smoking. Because smoking self-efficacy is a key predictor of remaining abstinent, it is important to examine how smoking self-efficacy may change over the course of a quit attempt and how changes in self-efficacy differ between sexes. In the present study, we tested whether abstinence during a smoking cessation intervention predicted changes in post-treatment smoking self-efficacy, and whether assigned sex moderated this relationship. We hypothesized that abstinence would be positively associated with increases in overall smoking self-efficacy and its facets, namely confidence abstaining in negative/affective-, positive/social-, and habit/addiction-related situations. Additionally, we hypothesized that among treatment non-responders (participants who did not remain abstinent), reduction in the number of past-week cigarettes from baseline to post-treatment would be associated with higher increases in smoking self-efficacy. Lastly, we also examined whether sex affected the relation between abstinence/cigarette reduction and self-efficacy, such that the relation between abstinence/cigarette reduction and self-efficacy would differ for AFAB smokers versus AMAB smokers. Because there are mixed findings regarding sex differences in self-efficacy, we made no specific hypotheses about the direction of the interaction, and these analyses were exploratory.