مسیرهای علی بین رفتار تکانشی، عواقب استفاده از کوکائین و افسردگی

Aims The present study examined whether lifetime cocaine use consequences mediate the relationship between trait impulsiveness and current depression symptoms among regular cocaine users. Methods Regular cocaine users (N = 108) were assessed using: Barratt Impulsiveness Scale subscales (non-planning, attentional, motor sub-scales) to measure trait impulsiveness; a standardized Drug History and Use Questionnaire to measure cocaine use and related consequences; and Beck Depression Inventory to measure current depression symptoms. Results All impulsiveness subscales were positively associated with an earlier age of first cocaine use, a higher degree of current depression symptoms and a greater number of lifetime cocaine use consequences. In three separate simple mediation tests, lifetime cocaine use consequences partially mediated the relationship between each of the impulsiveness subscales (non-planning: R2 = .42; attentional: R2 = .40; motor: R2 = .24) and current depression symptoms. Separate moderated mediation analyses failed to demonstrate an interaction between lifetime cocaine use and cocaine-related consequences predicting depression symptoms for the mediation models. Conclusions Cocaine-related consequences function in a more nuanced manner than just an outcome of impulsiveness or cocaine use, but as a pathway between trait impulsiveness and current depression symptoms.

Regular cocaine users report higher levels of trait impulsiveness than non-users (Coffey et al., 2003, Patkar, Murray, et al., 2004, Poling et al., 2007 and Vonmoos et al., 2013). More importantly from the standpoint of clinical prediction, high trait impulsiveness is associated with increased cocaine use quantity and long-term cocaine consumption (Moeller et al., 2001 and Vonmoos et al., 2013), increased craving (Tziortis, Mahoney, Kalechstein, Newton, & De La Garza, 2011), fewer days of treatment attendance (Moeller et al., 2001 and Patkar, Murray, et al., 2004), greater withdrawal symptom severity (Moeller et al., 2001), and a greater number of depression symptoms (Vonmoos et al., 2013). Regular cocaine users also report substantially higher rates of lifetime major depression (Falck et al., 2004 and Herrero et al., 2008) and current major depression (Rounsaville et al., 1991) than non-users. Hasin et al. (2002) examined the time sequence of depression and cocaine and substance dependence; participants demonstrated nearly four times the likelihood of substance-induced or abstinence-induced major depression compared to prior-onset major depression. Comorbid depression among regular cocaine users has been associated with greater urges to use cocaine during treatment (Brown et al., 1998), increased subjective high when using cocaine and increased depressive symptoms during initial abstinence (Ulsaner, Kalechstein, Richter, Ling, & Newton, 1999), greater likelihood of relapse (Hasin et al., 2002 and McKay et al., 2002), and poorer medication response aimed at reducing cocaine use (Gonzalez, Feingold, Oliveto, Gonsai, & Kosten, 2003). Impulsiveness is a multi-dimensional construct tied to antecedents and consequences of cocaine and other drug dependence (de Wit, 2009, Perry and Carroll, 2008 and Winstanley et al., 2010), making it important to distinguish mechanisms of influence. There are several pathways through which impulsiveness might alter the expression (e.g., course, severity) of cocaine use, abuse, and dependence. For instance, recent data indicate that cocaine users with higher (vs. lower) trait impulsiveness have reduced frontal–cortical gray matter (Crunelle et al., 2014 and Moreno-Lopez et al., 2012), which may perpetuate cocaine use and exacerbate its long-term adverse consequences via reduced executive control of behavior (Jentsch & Taylor, 1999) and/or emotion dysregulation (Fox, Axelrod, Paliwal, & Sinha, 2007). One pathway that may connect impulsiveness to depression is through chronic cocaine use-related adverse consequences. In a recent study, higher trait impulsiveness among recreational and dependent cocaine users was correlated with greater depression symptoms and long-term cocaine consumption (Vonmoos et al., 2013). High levels of trait impulsiveness among regular cocaine users seem to increase risk of greater cocaine-use consequences and comorbid depression symptoms (Moeller et al., 2001 and Vonmoos et al., 2013). Although clinically relevant, it is not clear how trait impulsiveness exerts an influence on depression symptoms among chronic cocaine users. Thus, the aim of the present investigation was to examine the psychological mechanisms and outcomes associated with regular cocaine use. To accomplish this aim, we assessed trait impulsiveness, lifetime cocaine use and related consequences, and current depression symptoms among a sample of regular cocaine users. We specifically evaluated whether lifetime cocaine use consequences might mediate the relationship between trait impulsiveness and current depression symptoms. A variable can be considered a mediator, “to the extent that it accounts for the relation between predictor and criterion” ( Baron & Kenny, 1986, p. 1176). Mediation analyses are advantageous because causality can be prioritized with the independent variable (i.e., trait impulsiveness) preceding the mediator (i.e., lifetime cocaine use consequences) in temporal sequence to predict the criterion (i.e., current depression symptoms; Baron & Kenny, 1986). We theorized that depression symptoms would primarily function as an outcome of impulsive cocaine use-related consequences (see Hasin et al., 2002). To test this possibility, we hypothesized that the number of lifetime cocaine use negative consequences would mediate the relationship between trait impulsiveness and acute depression symptoms. Specifically, we predicted that regular cocaine users with a higher degree of trait impulsiveness would experience a greater number of lifetime cocaine use consequences and, as a result, experience a higher degree of current depression symptoms.

3.1. Sample demographics, cocaine use, trait impulsiveness, and current depression symptoms The sample (N = 108) was primarily male (n = 88, 81.5%) and African-American (n = 87, 80.6%). Age of participants ranged from 24–57 years old (M = 45.5, SD = 7.1). Forty-two percent (n = 45) of participants completed some high school or a high school degree (or equivalent), nearly half (n = 53, 49.1%) had attended college, and the remaining participants (n = 10, 9.3%) completed a bachelor's degree or more. Participants typically used cocaine for the first time during their mid-20's (M = 25.1, SD = 7.2), with regular use beginning on average less than three years later (M = 27.6, SD = 7.2). Participants' duration of time since first cocaine use was about 20 years (M = 20.4, SD = 8.2), with duration of regular use roughly three years fewer (M = 17.9, SD = 8.0). Participants reported using cocaine roughly half the days over the past month (M = 15.2, SD = 8.8) and using cocaine, on average, every other day during the past week (M = 3.5, SD = 2.1). Participants reported using cocaine about four times per day (M = 4.0, SD = 3.7). Smoking crack cocaine (n = 91, 84.3%) was the most common current route of administration; all remaining participants reported snorting (n = 15, 13.9%) as current route. Most participants (n = 79, 73.1%) provided a cocaine positive urine sample at screening, and roughly a third of participants (n = 34, 32.1%) had a THC positive urine sample. Total scores on the DHUQ consequences scale ranged from 0–17 (maximum possible score = 18), with participants reporting an average of about five lifetime cocaine use negative consequences (M = 4.9, SD = 4.2). Scores for the BIS-11 impulsiveness subscales were as follows: attentional (M = 15.1, SD = 4.1), motor (M = 23.4, SD = 5.0), and non-planning (M = 26.4, SD = 5.8). Participants' current depression symptom total scores ranged from 0–39 (M = 12.3, SD = 10.0). BDI-II scores of 14 or more indicate clinically relevant symptoms of depression ( Beck et al., 1996) (n = 42, 38.9%). Within this sample, approximately one in six participants reported mild depression (scores of 14–19; n = 17, 15.7%), nearly one in ten reported moderate depression symptoms (scores of 20–28; n = 10, 9.3%), and approximately one in eight participants reported severe depression symptoms (scores of 29–63; n = 13, 12.0%). 3.2. Correlations among trait impulsiveness, cocaine use and cocaine-related consequences, and current depression symptoms Table 1 presents correlations among the major study variables (trait impulsiveness subscales, lifetime cocaine use, lifetime cocaine use consequences, current depression symptoms) that were used in mediation analyses, as well as age of cocaine use onset and age of regular cocaine use. Positive relationships were observed between scores for all three impulsiveness subscales and current depression symptoms. All three impulsiveness subscales were positively associated with lifetime cocaine use consequences. A higher total number of lifetime cocaine use consequences were associated with higher current depression symptom scores. A greater number of lifetime cocaine uses were positively associated with a greater number of lifetime cocaine use consequences but unrelated to current depression symptoms. Higher non-planning impulsiveness was associated with a greater number of lifetime cocaine uses. Because lifetime cocaine use was not associated with current depression symptoms, mediation analysis was not conducted with this variable.