Although early results are promising, integrated treatments are not fully empirically-supported, suggesting that further research examining core therapeutic processes within this patient population is needed. Mediators are intervening variables that statistically explain some association between an independent variable and dependent variable . Within the substance dependence treatment literature, researchers have increasingly stressed the importance of studies that seek to identify the mediators of treatment effects with some noting this needs to be “a first priority” . Within the depression treatment literature a similar movement has occurred in parallel . By gaining a greater understanding of the specific processes involved in treatment, therapies can be improved and disseminated more easily into practice settings . However, the search for treatment-specific mediators has often been less than promising, with theoretically dissimilar therapies often producing equivalent treatment effects or showing no differential change on theory-based mediators, and some recommending a paradigm shift in substance use treatment research . However, even studies of alternative treatments with similar effects on mediators and outcomes can provide useful insight into the common mechanisms of treatments, distinct but similarly effective mechanisms, or some combination of both . Previous studies have found that coping skills , self-efficacy ,and social support were common mechanisms of both cognitive-behavioral therapies and comparison interventions, due to similar levels of these variables across treatments and similar magnitude of associations between mechanisms and outcome. While these “null difference” findings are in some ways disappointing , they identify therapeutic processes that generally predict positive outcomes across different treatments. In other studies self efficacy and coping skills were treatment-specific mediators of cognitive behavioral interventions, because greater levels or change were attained and were predictive of group superior reductions in substance use, suggesting that under certain conditions, certain treatments do elicit differential change on therapeutic process variables.
Some of the more robust treatment-specific mediators have been 12-step attendance and affiliation,cannabis grower with greater increases in these mediators repeatedly found for treatments that explicitly encourage 12-step activities . In addition, change in social support for abstinence has been specific mediator of outcome in treatments designed to change social networks . Mediators of substance use may also relate to other outcomes, as one study found greater 12-step meeting attendance was associated with future drinking but also with lower current depressive symptoms . Amid the questionable efficiency in continued reliance on large-scale randomized controlled trials and scrutiny of these designs, further research in proximal variables that mediate treatment outcomes or predict outcomes across treatment conditions has an important role in the further development of substance dependence interventions. Few studies have examined mediators of outcome in patients with substance dependence and psychiatric disorders, and almost none have involved integrated treatments that simultaneously target both disorders. In naturalistic studies of community based, dual-focus self-help groups, the effects of greater meeting attendance and 12-step affiliation on abstinence were mediated by social support, sociability, internal locus of control, and self-help processes . In an observational study of residential treatment, self-efficacy and social support at baseline predicted psychological distress and substance use at follow-up in patients with substance dependence and mixed psychiatric disorders . In one randomized, controlled study, changes in negative mood expectancies predicted long-term alcohol use in patients receiving adjunctive CBT for depression in patients receiving relaxation training . In a study of our sample of veterans with substance dependence and MDD, self-efficacy predicted time to relapse and frequency of substance use during treatment . None of these studies conducted formal statistical tests for mediation, a necessary criterion for the establishment of an intervening variable as a mechanism of change , along with the temporal precedence. There is initial evidence that therapeutic processes involved in substance use treatment and maintenance of abstinence will translate to those with co-occurring MDD, but this literature is currently lacking in methodologically-sound, longitudinal investigations.
In addition to therapeutic process variables identified in general substance dependence treatment studies, level of negative affect likely plays a large role in the maintenance of substance use for individuals with substance dependence and MDD. Negative affect is frequently a precursor to substance use and is dynamically-linked to alcohol and drug use following treatment . These associations may be even stronger in adults with SUDs and MDD, who likely have stronger urges to “self-medicate” with substances to manage depressive symptoms. In one study comparing SUD-only patients to those with SUDs and psychiatric disorders, those with co-occurring MDD were especially likely to experience depressive symptoms prior to relapse . Furthermore, changes in depression and substance use during treatment and follow-up were strongly correlated in our sample of veterans with substance dependence and MDD In addition to the significance of depression severity as proximal risk factor for substance use, the magnitude of improvement in depression during treatment is a potential mechanism of change for substance use behaviors in this population. Prior research suggests the salutary effects of AA meetings on drinking may be explained, in part, by related improvements in depression . Treatment processes or individual characteristics that relate to depression may be especially potent for patients with SUDs and MDD, but prior studies have not examined these effects during or following outpatient treatment for these co-occurring disorders. Models of post-treatment relapse characterize the mediating variables discussed above as critical proximal determinants of substance use but also emphasize the significance of more “distal” risk variables . As such, investigations of mediating variables should also consider the impact of such distal risks on the therapeutic process.Despite a strong clinical rationale that patients with neurocognitive deficits will have poorer outcomes from psychological treatments, especially those that engage higher-order cognitive functions , most studies examining this hypothesis have yielded weak and inconsistent results .
More recently, two studies have examined more indirect effects of neurocognitive impairment: as a predictor of mediating variables, and as a moderator of their effects on substance use. Interestingly, both studies found that greater impairment was linked to lower self-efficacy during treatment, and that therapeutic effects of self efficacy were weaker for impaired patients . These studies highlight complex interactions between variables at different levels of analysis, which are required to fully elucidate our understanding of individual differences in substance dependence treatment outcome. Neurocognitive effects on therapeutic change mechanisms could be similar or even more pronounced in patients with co-occurring MDD. Neurocognitive features of MDD share many impairments with substance dependence, including deficits in memory , processing speed and executive function . Furthermore, better neurocognitive functioning at baseline has predicted greater reductions in depression for patients with depressive symptoms and hazardous alcohol use . This finding in particular suggests impairment is related to recovery from depressive symptoms, an important determinant of substance use for patients with substance dependence and MDD . A prior study of our sample found better substance use outcomes for veterans with poorer cognitive functioning who received integrated CBT as compared to TSF, a result that was somewhat unexpected given the theoretically greater cognitive demands in CBT . Given these prior findings, determining whether neurocognitive impairment interrupts therapeutic change mechanisms has important implications for clinical practice, but these questions have not been examined in patients with co-occurring substance dependence and MDD. Compared to recently emerging literature examining mediators and moderators of outcome in substance-dependent patients,vertical grow systems for sale there is a paucity of research examining these factors in patients with SUDs and co-occurring psychiatric disorders, who are more costly to treat , at greater risk of suicide , are more disabled , and typically have poorer treatment outcomes . The proposed series of studies will make significant contributions in this area of need by focusing on the largest group of substance-dependent adults with co-occurring psychiatric disorders, those with MDD. Results will assist in delineating the specific processes involved in the reduction of both substance use and depressive symptoms over time in this prevalent, chronically disabled, and costly population. The studies will conduct examinations of mediating processes, to explain associations between predictor variables and outcomes . These studies will examine whether specific proximal variables are common mechanisms of change, by highlighting whether specific intrapersonal processes are predictive of outcome regardless of treatment orientation. In addition, results may show that processes traditionally targeted to improve substance use may generalize to depressive symptoms, which has direct implications for clinical practice. By including outcomes up to one-year post treatment, these studies will seek to identify key processes involved in the long-term maintenance of symptom improvement. In addition, this study may be the first to elucidate pathways through which neurocognitive impairment impacts outcome in patients with substance dependence and MDD, which will have significant implications for the treatment of patients with neurocognitive impairment. Compared to the general population, mood and anxiety disorders occur at higher rates among individuals with substance use disorders , and major depression is the most common comorbid Axis I psychiatric disorder . Comorbid MDD is associated with a more chronic and prolonged course of SUDs , higher rates of disability , greater treatment costs and elevated risk of suicide . The prevalence is even greater among those who receive SUD treatment; in some clinical settings over half of patients have MDD .
These patients often have greater severity of problems at intake and poorer outcomes from alcohol or drug treatment . Despite high prevalence and evidence that treatment is less effective, few studies have examined treatment processes within this population. Recent research in SUD interventions has increasingly focused on mechanisms of change, defined as the factors that explain how and why treatments work . Studies of mediators, or variables that account for the association between a predictor and outcome , are a core element of this research . However, these factors have rarely been investigated in patients with SUD and comorbid MDD, which hinders the advancement of interventions for this patient population. Some of the most frequently-studied mediators of SUD treatment have been variables related to 12-step involvement, including attendance at 12-step meetings and participation in 12-step activities . In general SUD samples these variables are consistently associated with reduced alcohol and drug use and mediated the effects of 12-step psychotherapies in clinical trials . However, among patients with comorbidity studies of 12-step involvement have yielded inconsistent findings. In some studies, patients with psychiatric comorbidity attended similar levels of 12-step meetings and experienced similar benefits as those without psychiatric conditions , but others found reduced benefits of 12-step involvement for patients with comorbid MDD . Issues inherent to some community meetings, such as attitudes about psychiatric medication, could interfere with participation . In light of the limited existing research, further studies are needed to evaluate the utility of 12-step involvement in this population. A more complete understanding of 12-step variables may be achieved by examining mediators of therapeutic effects. Among patients with MDD one potential mediating variable is depressive symptoms. Affect regulation is frequently described in the 12-step literature , and 12-step involvement may increase exposure to common therapeutic factors that could reduce depressive symptoms . Therapeutic changes in mood could play a key role in substance use outcomes, as negative affect is often implicated in relapse and reductions in depression over time are associated with reduced alcohol and drug use . In a secondary analysis of Project MATCH , lower depression explained the effects of Alcoholics’ Anonymous attendance on future drinking, but this was mostly attributable to AA’s effects on current drinking . The relative role of depression in mediating 12-step involvement could be greater for patients with comorbid MDD. Depressive symptoms are a prevalent precipitant of relapse for these patients , and prior research with this sample found strong correlations between individual changes in depression and substance use . Thus, improvement in depressive symptoms linked to 12-step involvement could be a key process in the reduction of substance use for patients with SUD and MDD. The goal of this study was to examine relations between 12-step involvement, depression, and substance use in patients receiving treatment for comorbid SUD and MDD. Veterans with alcohol or drug dependence and MDD received antidepressant pharmacotherapy and 6 months of group psychotherapy with either Twelve-Step Facilitation or Integrated Cognitive-Behavioral Therapy , a cognitive behavioral treatment that focused jointly on depression and substance use .