Anhedonia, depressed mood, and smoking cessation outcome.

The relation between lifetime depression and smoking cessation outcome has been extensively studied, but remains poorly understood. One important barrier to understanding this association is that important sources of variation within depression may alter how depression confers risk of smoking relapse. Indeed, a recent meta-analytic study showed a modest but statistically significant overall relation between pre-quit lifetime depression status and post-quit relapse risk (Hitsman et al., 2013), but also identified several moderators of this relation, including recency of depression, type of depression measure, and other factors (Hitsman et al., 2013). Other research that indicates that recurrence is another important source of heterogeneity, as recurrent (vs. single episode) forms of lifetime depression predict poorer cessation outcome (Brown et al., 2001; Haas, Munoz, Humfleet, Reus, & Hall, 2004). One important, yet often overlooked, issue is depression's symptomatic heterogeneity. Depression comprises a diverse array of symptoms spanning affective (e.g., sadness), behavioral (e.g., psychomotor changes), cognitive (e.g., concentration problems), and vegetative (e.g., sleep and appetite disruption) features that loosely cluster together (Zimmerman, McGlinchey, Young, & Chelminski, 2006). Given the diversity of depressive symptoms, is possible that only certain symptomatic expressions of depression increase risk of relapse, whereas others are relatively benign with regard to smoking cessation. Thus, combining all symptoms of depression into a single diagnostic category may increase error and obscure important variability in relapse risk within the population of smokers with lifetime depressive symptoms and syndromes. Anhedonia (i.e., diminished interest or pleasure in normally enjoyable activities) and depressed mood (i.e., elevated sadness) constitute the two hallmark features of depression (APA, 1994). Either anhedonia or depressed mood is required (in addition to at least four other symptoms) to qualify for a DSM-IV major depression diagnosis (APA, 1994). Although they are both key symptoms of the same syndrome (i.e., depression), anhedonia and depressed mood are empirically distinct (Zimmerman et al., 2006; i.e., anhedonia commonly occurs without concurrent depressed mood and depresssed mood occurs without concurrent anhedoina), have unique neural correlates (Wacker, Dillon, & Pizzagalli, 2009), and are putatively distinct depressive endophenotypes (Hasler, Drevets, Manji, & Charney, 2004). Research suggests that these two facets of depression are particularly relevant for smoking cessation because they both appear to impact smoking motivation and do so via discrete mechanisms. There is copious evidence that negative affect states, including sadness, influences smoking motivation (Baker, Piper, McCarthy, Majeskie, & Fiore, 2004; Falcone et al., 2012; Leventhal et al., 2013; Litvin & Brandon, 2010). Further, trait depressed mood and negative affect predict greater exacerbations in state negative affect and urge to smoke for negative affect relief upon tobacco abstinence (Gilbert et al., 1998; Leventhal et al., 2013). Anhedonia is also associated with smoking motivation and some research suggests that anhedonic individuals smoke in order to enhance the ability to enjoy activities and experience pleasure (Cook, Spring, & McChargue, 2007; Leventhal, Waters, Kahler, Ray, & Sussman, 2009). Furthermore, anhedonia predicts declines in state positive affect as well as increases in urge to smoke for pleasure upon tobacco abstinence (Cook, Spring, McChargue, & Hedeker, 2004; Leventhal, Ameringer, Osborne, Zvolensky, & Langdon, in press; Leventhal et al., 2009). Thus, the overarching depression construct could heighten risk of cessation failure via two distinct contingencies: (1) omission training whereby abstinence produces deficits in positive affect in anhedonic individuals, which results in a “time out” from reward and strong drive to re-attain smoking-mediated reward, and/or (2) negative reinforcement in which smokers with depressed mood become hyper motivated to escape the distress (negative affect) of withdrawal. Despite the putatively important roles of anhedonia and depressed mood in smoking, empirical data on the relative risk of smoking relapse conferred by lifetime anhedonia and depressed mood is lacking. Yet, distilling the elements of depression that most powerfully predict smoking cessation failure could: (1) elucidate the motivational processes that maintain addiction, (2) meaningfully increase the prediction of cessation failure by reducing error in the predictor, and (3) suggest new relapse prevention interventions that address the core elements of depression-related vulnerability. The current study addresses two critical questions in an effort to distill the depression phenotype as it is related to risk of cessation failure. Does lifetime anhedonia or depressed mood (irrespective of whether they occur in conjunction with a clinical depressive disorder) predict cessation outcomes? Do both types of affective symptoms make independent, additive contributions to prediction, or is one symptom prepotent in accounting for the relation? We focuses on affective as opposed to other types of depressive symptoms because prior cessation research using paper-and-pencil symptom indices illustrate that anhedonia and depressed mood predict poor cessation outcomes (Cook, Spring, McChargue, & Doran, 2010; Leventhal, Ramsey, Brown, LaChance, & Kahler, 2008; Niaura et al., 2001; c.f., Schnoll, Leone, & Hitsman, 2013), whereas non-affective dimensions of depression (e.g., somatic features manifested as sleep problems, appetite changes, concentration problems, and psychomotor slowing) do not directly or incrementally augment such predictions (Leventhal et al., 2008; Schnoll et al., 2013). Similarly, tobacco withdrawal research demonstrates that affective withdrawal symptoms predict cessation failure more consistently than non-affective withdrawal symptoms (McCarthy, Piasecki, Fiore, & Baker, 2006; Piasecki et al., 2000). Thus, affective features may perhaps capture relatively pure facets of depression that directly magnify smoking motivation during a quit attempt. We hypothesized that lifetime history of anhedonia and depressed mood would predict poorer cessation outcomes over and above lifetime DSM-IV classified depressive disorder, which represents an amalgam of cognitive, behavioral, and vegetative features. Given that anhedonia and depressed mood might impede smoking cessation through distinct affective mechanisms (i.e., reward enhancement vs. distress relief), we further hypothesized that these two features would yield additive predictive effects. This research will address these hypotheses using DSM-based interview assessment of anhedonia and depressed mood (Hitsman et al., 2011). Because DSM-based indices are commonly used in treatment settings, their use in this research permits broader and more immediate application of the knowledge derived from them.