Negative Affect Symptoms Research Articles

Ultrasonic Vocalizations as a Measure of Affect in Preclinical Models of Drug Abuse: A Review of Current Findings.

The present review describes ways in which ultrasonic vocalizations (USVs) have been used in studies of substance abuse. Accordingly, studies are reviewed which demonstrate roles for affective processing in response to the presentation of drug-related cues, experimenter- and self-administered drug, drug withdrawal, and during tests of relapse/reinstatement. The review focuses on data collected from studies using cocaine and amphetamine, where a large body of evidence has been collected. Data suggest that USVs capture animals’ initial positive reactions to psychostimulant administration and are capable of identifying individual differences in affective responding. Moreover, USVs have been used to demonstrate that positive affect becomes sensitized to psychostimulants over acute exposure before eventually exhibiting signs of tolerance. In the drug-dependent animal, a mixture of USVs suggesting positive and negative affect is observed, illustrating mixed responses to psychostimulants. This mixture is predominantly characterized by an initial bout of positive affect followed by an opponent negative emotional state, mirroring affective responses observed in human addicts. During drug withdrawal, USVs demonstrate the presence of negative affective withdrawal symptoms. Finally, it has been shown that drug-paired cues produce a learned, positive anticipatory response during training, and that presentation of drug-paired cues following abstinence produces both positive affect and reinstatement behavior. Thus, USVs are a useful tool for obtaining an objective measurement of affective states in animal models of substance abuse and can increase the information extracted from drug administration studies. USVs enable detection of subtle differences in a behavioral response that might otherwise be missed using traditional measures.

Unraveling the relationship between trait negative affectivity and habitual symptom reporting.

ObjectiveIn two studies, we aimed at further elucidating the relationship between trait negative affectivity (NA) and habitual symptom reporting (HSR) by relating these variables to measures of executive function, trait questionnaires, and effects of emotion induction.MethodsHealthy female participants (N = 75) were selected on their scores for trait NA and for the Checklist for Symptoms in Daily Life. Three groups were compared: (1) low NA-low HSR; (2) high NA-low HSR; and (3) high NA-high HSR (low NA-high HSR did not occur). In study 1, participants underwent a Parametric Go/No-go Task and a Stroop Color-Word test, and trait questionnaires measured alexithymia and absorption. Forty-five participants (N = 15 in each group) were further engaged in study 2 to induce state NA using an affective picture paradigm.ResultsImpaired inhibition on the Stroop and Go/No go Task characterized high trait NA, but not high HSR, whereas alexithymia and absorption were elevated in HSR, regardless of trait NA. Negative picture viewing induced elevated state NA in all groups, but only high HSR also reported more bodily symptoms. This effect was moderated, but not mediated by state NA.ConclusionHigh trait NA is a vulnerability factor but not a sufficient condition to develop HSR. Deficient inhibition is related to the broad trait of NA, whereas the moderating effect of state NA on symptom reporting is specific for high HSR. Understanding processes related to alexithymia and absorption may specifically help to explain elevated HSR.

Activity disruption and depressive symptoms in women living with metastatic breast cancer.

Women with breast cancer are at increased risk of depression, and the extent to which valued activities are disrupted by one's illness has been correlated with depressive symptoms in women with early stage breast cancer. This association has not been examined in women with Stage IV (metastatic) cancer, and the temporal directionality of this relationship remains unclear. The goal of the current study was to examine longitudinal, reciprocal relationships between illness-related disruption of social and recreational activities and self-reported symptoms of depression in a sample of women living with Stage IV breast cancer. Participants were 103 women diagnosed with metastatic breast cancer. Women completed measures of depressive symptoms and activity disruption at study entry (T1) and at 3-month follow-up (T2). Activity disruption at study entry did not significantly predict changes in total depressive symptoms or in negative affective or somatic symptoms but did predict reductions in positive affect. Total depressive symptoms at study entry predicted increases in activity disruption, as did negative affective symptoms. Depressive symptoms, specifically negative affective symptoms such as sadness, may exacerbate social and recreational activity disruption in women with metastatic breast cancer. Cancer-related activity disruption may, in turn, result in reductions in positive affect. These results highlight the importance of examining specific constellations of depressive symptoms and suggest that maintaining valued activities may help to preserve enjoyment of life for patients with Stage IV cancer.

Loving-Kindness Meditation to Target Affect in Mood Disorders: A Proof-of-Concept Study.

Conventional treatments for mood disorders primarily focus on reducing negative affect, but little on enhancing positive affect. Loving-kindness meditation (LKM) is a traditional meditation practice directly oriented toward enhancing unconditional and positive emotional states of kindness towards oneself and others. We report here two independent and uncontrolled studies carried out at different centers, one in Boston, USA (n = 10), and one in Frankfurt, Germany (n = 8), to examine the potential therapeutic utility of a brief LKM group intervention for symptoms of dysthymia and depression. Results at both centers suggest that LKM was associated with large-sized effects on self-reported symptoms of depression (d = 3.33 and 1.90), negative affect (d = 1.98 and 0.92), and positive affect (d = 1.63 and 0.94). Large effects were also found for clinician-reported changes in depression, rumination and specific positive emotions, and moderate effects for changes in adaptive emotion regulation strategies. The qualitative data analyses provide additional support for the potential clinical utility of the intervention. This proof-of-concept evaluation of LKM as a clinical strategy warrants further investigation.

Affect and psychiatric symptoms in a veteran polytrauma clinic.

Although the relationship between negative affect and psychiatric symptoms has been well-demonstrated in research, less is known about positive affect relative to negative affect, and its relationship to psychiatric symptoms, especially among veterans. This study examined how levels of positive and negative affect are associated with symptoms of depression, anxiety, and posttraumatic stress disorder (PTSD). Data were collected in a veteran polytrauma clinic; analyses were conducted using data from 94 veterans (87 males) with and without a mild traumatic brain injury (mTBI) diagnosis. Results demonstrate that positive and negative affect were separate dimensions and that both were independently related to each symptom measure. After removing the contribution of negative affect from symptom reports, strong relationships remained between positive affect and psychiatric symptoms. Furthermore, the magnitude of the associations for positive affect and for negative affect with symptoms of depression, anxiety, and PTSD were not impacted by a mTBI diagnosis. Altogether, findings suggest that both positive and negative affect should be uniquely considered when conceptualizing, assessing, and treating returning service members; in addition, positive affect may be an appropriate target of assessment and interventions of persons who have experienced polytrauma.

Functional significance of a novel 7-factor model of DSM-5 PTSD symptoms: Results from the National Health and Resilience in Veterans Study

BackgroundWhile posttraumatic stress disorder (PTSD) symptoms in the recently published Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) are clustered into four factors, emerging confirmatory factor analytic studies suggest that this disorder is best characterized by seven symptom clusters, including re-experiencing, avoidance, negative affect, anhedonia, externalizing behaviors, and anxious and dysphoric arousal symptoms. To date, however, data are lacking regarding the relation between this novel model of DSM-5 PTSD symptoms and measures of clinical significance in this population (e.g., functioning). MethodsUsing data from the National Health and Resilience in Veterans Study (NHRVS), a contemporary, nationally representative sample of 1484 U.S. veterans, we evaluated clinical and functional correlates of a novel 7-factor model of DSM-5 PTSD symptoms. ResultsDifferential patterns of associations were observed between DSM-5 PTSD symptom clusters, and psychiatric comorbidities, suicidal ideation, hostility, and functioning and quality of life. Anhedonia symptoms, in particular, were strongly related to current depression, as well as reduced mental functioning and quality of life. Externalizing behaviors were most strongly related to hostility, supporting the convergent validity of this construct. LimitationsCross-sectional design and employment of self-report measures. ConclusionsThese results suggest that a more refined 7-factor model of DSM-5 PTSD symptoms may provide greater specificity in understanding associations with comorbid psychopathology, suicidal ideation, and functioning and quality of life in U.S. veterans. They further suggest that prevention and treatment efforts that target distinct aspects of the PTSD phenotype may be more effective in mitigating key clinical and functional outcomes in this population.

Daily positive spillover and crossover from mothers' work to youth health.

Prior research shows that employees' work experiences can "spill over" into their family lives and "cross over" to affect family members. Expanding on studies that emphasize negative implications of work for family life, this study examined positive work-to-family spillover and positive and negative crossover between mothers and their children. Participants were 174 mothers in the extended care (nursing home) industry and their children (ages 9-17), both of whom completed daily diaries on the same 8 consecutive evenings. On each workday, mothers reported whether they had a positive experience at work, youth reported on their mothers' positive and negative mood after work, and youth rated their own mental (positive and negative affect) and physical health (physical health symptoms, sleep quality, sleep duration). Results of 2-level models showed that mothers' positive mood after work, on average, was directly related to youth reports of more positive affect, better sleep quality, and longer sleep duration. In addition, mothers with more positive work experiences, on average, displayed less negative mood after work, and in turn, adolescents reported less negative affect and fewer physical health symptoms. Results are discussed in terms of daily family system dynamics.

Methamphetamine differentially affects BDNF and cell death factors in anatomically defined regions of the hippocampus

Methamphetamine exposure reduces hippocampal long-term potentiation (LTP) and neurogenesis and these alterations partially contribute to hippocampal maladaptive plasticity. The potential mechanisms underlying methamphetamine-induced maladaptive plasticity were identified in the present study. Expression of brain-derived neurotrophic factor (BDNF; a regulator of LTP and neurogenesis), and its receptor tropomyosin-related kinase B (TrkB) were studied in the dorsal and ventral hippocampal tissue lysates in rats that intravenously self-administered methamphetamine in a limited access (1h/day) or extended access (6h/day) paradigm for 17days post baseline sessions. Extended access methamphetamine enhanced expression of BDNF with significant effects observed in the dorsal and ventral hippocampus. Methamphetamine-induced enhancements in BDNF expression were not associated with TrkB receptor activation as indicated by phospho (p)-TrkB-706 levels. Conversely, methamphetamine produced hypophosphorylation of N-methyl-d-aspartate (NMDA) receptor subunit 2B (GluN2B) at Tyr-1472 in the ventral hippocampus, indicating reduced receptor activation. In addition, methamphetamine enhanced expression of anti-apoptotic protein Bcl-2 and reduced pro-apoptotic protein Bax levels in the ventral hippocampus, suggesting a mechanism for reducing cell death. Analysis of Akt, a pro-survival kinase that suppresses apoptotic pathways and pAkt at Ser-473 demonstrated that extended access methamphetamine reduces Akt expression in the ventral hippocampus. These data reveal that alterations in Bcl-2 and Bax levels by methamphetamine were not associated with enhanced Akt expression. Given that hippocampal function and neurogenesis vary in a subregion-specific fashion, where dorsal hippocampus regulates spatial processing and has higher levels of neurogenesis, whereas ventral hippocampus regulates anxiety-related behaviors, these data suggest that methamphetamine self-administration initiates distinct allostatic changes in hippocampal subregions that may contribute to the altered synaptic activity in the hippocampus, which may underlie enhanced negative affective symptoms and perpetuation of the addiction cycle.

Dimensional structure of DSM-5 posttraumatic stress symptoms: Support for a hybrid Anhedonia and Externalizing Behaviors model

Several revisions to the symptom clusters of posttraumatic stress disorder (PTSD) have been made in the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Central to the focus of this study was the revision of PTSD's tripartite structure in DSM-IV into four symptom clusters in DSM-5. Emerging confirmatory factor analytic (CFA) studies have suggested that DSM-5 PTSD symptoms may be best represented by one of two 6-factor models: (1) an Externalizing Behaviors model characterized by a factor which combines the irritability/anger and self-destructive/reckless behavior items; and (2) an Anhedonia model characterized by items of loss of interest, detachment, and restricted affect. The current study conducted CFAs of DSM-5 PTSD symptoms assessed using the PTSD Checklist for DSM-5 (PCL-5) in two independent and diverse trauma-exposed samples of a nationally representative sample of 1484 U.S. veterans and a sample of 497 Midwestern U.S. university undergraduate students. Relative fits of the DSM-5 model, the DSM-5 Dysphoria model, the DSM-5 Dysphoric Arousal model, the two 6-factor models, and a newly proposed 7-factor Hybrid model, which consolidates the two 6-factor models, were evaluated. Results revealed that, in both samples, both 6-factor models provided significantly better fit than the 4-factor DSM-5 model, the DSM-5 Dysphoria model and the DSM-5 Dysphoric Arousal model. Further, the 7-factor Hybrid model, which incorporates key features of both 6-factor models and is comprised of re-experiencing, avoidance, negative affect, anhedonia, externalizing behaviors, and anxious and dysphoric arousal symptom clusters, provided superior fit to the data in both samples. Results are discussed in light of theoretical and empirical support for the latent structure of DSM-5 PTSD symptoms.

Actor–partner model of physiology, negative affect, and depressive symptoms in mother–child dyadic interactions

Mother–child interactions can be emotionally charged, particularly when mothers experience difficulties with depression. Further, variation in the tone of such interactions has been linked to variation in youth functioning. Yet, little is known about the role of emotion regulatory processes during mother–child interactions. This study examined negative affective transactions between mothers and youth across 5-min conflict and fun-activity planning discussions, in relation to depressive symptoms and maternal and youth respiratory sinus arrhythmia (RSA). Maternal depressive symptoms predicted more negative affect. Maternal and youth RSA interacted with maternal depressive symptoms to predict both overall affect and the stability of affect across time. The beneficial effects of youth RSA were stronger, but maternal RSA weaker, in the face of elevated maternal depression.

Identity Distress and Negative Affect in College Students

Many young people attend college during the peak years of identity exploration. This research examines the prevalence of identity distress among college students and the degree to which participants may meet the DSM-IV classification for identity problem. In addition, this study examines the extent to which participants with high levels of identity distress report symptoms of depression and other symptoms of negative affect. Findings indicated that 8.1% of the sample met the DSM-IV description for identity problem as assessed with the Identity Distress Survey. Those who met the criteria for identity problem reported significantly more loneliness, overwhelming anger, hopelessness, and depression, compared with those without identity problem. The identity areas of long-term goals, friendships, and career were more likely to be rated as causing severe distress and were more likely to be associated with specific negative affect symptoms. Implications regarding prevention programming for emerging adults and college students in particular are discussed.

A test of the stress-buffering model of social support in smoking cessation: is the relationship between social support and time to relapse mediated by reduced withdrawal symptoms?

Social support has been linked to quitting smoking, but the mechanisms by which social support affects cessation are poorly understood. The current study tested a stress-buffering model of social support, which posits that social support protects or "buffers" individuals from stress related to quitting smoking. We hypothesized that social support would be negatively associated with risk of relapse, and that this effect would be mediated by reduced withdrawal and depressive symptoms (i.e., cessation-related stress) over time. Further, we predicted that trait neuroticism would moderate this mediational effect, such that individuals high in negative affectivity would show the greatest stress-buffering effects of social support. Participants were weight-concerned women (n = 349) ages 18-65 enrolled in a randomized, double-blind, placebo-controlled smoking cessation trial of bupropion and cognitive behavioral therapy. Social support was assessed at baseline, and biochemically-verified abstinence, withdrawal-related symptoms, and depressive symptoms were assessed at 1-, 3-, 6-, and 12-months follow-up. Social support was negatively related to risk of relapse in survival models and negatively related to withdrawal symptoms and depression in mixed effects models. These relationships held after controlling for the effects of pre-quit day negative affect and depression symptoms, assignment to treatment condition, and number of cigarettes smoked per day. A temporal mediation model showed that the effect of social support on risk of relapse was mediated by reductions in withdrawal symptoms over time but not by depression over time. Contrary to hypotheses, we did not find that neuroticism moderated this mediation effect. Increased social support may buffer women from the harmful effects of cessation-related withdrawal symptoms, which in turn improve cessation outcomes.

Depression and anxiety symptoms moderate the relation between negative reinforcement smoking outcome expectancies and nicotine dependence.

Smoking reinforcement expectancies-expectations that smoking modulates mood-can be powerful motivators to smoke, resulting in increased nicotine dependence. The impact of smoking reinforcement expectancies on nicotine dependence may be particularly strong in individuals with increased mood or anxiety symptoms because they may be more likely to act on expectancies with smoking behavior in order to offset their affective symptoms. This study examined levels of emotional symptom dimensions as moderators of the relation between positive and negative smoking reinforcement expectancies and nicotine dependence severity in a community sample. In a cross-sectional design, 317 daily cigarette smokers (215 men) completed self-report measures of smoking reinforcement expectancies, mood and anxiety symptoms, and nicotine dependence. Increasing levels of negative affect and anxiety symptoms strengthened associations between negative reinforcement smoking expectancies and nicotine dependence severity (moderation effects; (βs > .13; ps < .03) but did not moderate relations between positive reinforcement expectancies and dependence. Anhedonia did not moderate relations involving either positive or negative reinforcement smoking expectancies. Distinct components of anxiety and depressive symptoms interact differently with smoking reinforcement expectancies. Emotional symptoms characterized by excesses in aversive (but not deficits in appetitive) functioning may amplify tendencies to compulsively act on negative reinforcement expectancies by smoking. Cessation treatments that target negative reinforcement expectancies may be particularly salient for emotionally distressed smokers.

SY22-2 * STRUCTURE OF CRAVING IN NICOTINE ADDICTION

The aim of this session is to analyze and compare the structure of craving among nicotine, other substances, and behavioral addiction. Craving is hypothesized to be composed of three determinants. The first is the primary reinforcing property of a substance. The potential of nicotine as a primary reinforcer is weaker than that of other substances. On the other hand, it is difficult to define the primary reinforcing property in behavioral addiction. With regard to induction of craving, compensatory desensitization of the reward system that mediates the positive reinforcing property is considered to form a basic component of craving, and can be commonly observed both in substance addiction and in behavioral addiction. The second determinant is the secondary reinforcing property of a substance (conditioned aspects of the environment, such as contextual or specific cues associated with substance taking). Nicotine shows a robust conditioning property. The third determinant to elicit craving is the negative affective motivational property during withdrawal. Nicotine produces negative affective symptoms with a lesser degree of somatic withdrawal signs. As for the secondary conditioning processes and the negative motivational aspects of withdrawal, both substance and behavioral addiction have similar characteristics in nature. Treatment strategy is discussed using this hypothesis.

Mindfulness predicts lower affective volatility among African Americans during smoking cessation.

Recent research suggests that mindfulness benefits emotion regulation and smoking cessation. However, the mechanisms by which mindfulness affects emotional and behavioral functioning are unclear. One potential mechanism, lower affective volatility, has not been empirically tested during smoking cessation. This study examined longitudinal associations among mindfulness and emotional responding over the course of smoking cessation treatment among predominantly low-socioeconomic status (SES) African American smokers, who are at high risk for relapse to smoking and tobacco-related health disparities. Participants (N = 399, 51% female, mean age = 42, 48% with annual income <$10,000) completed a baseline measure of trait mindfulness. Negative affect, positive affect, and depressive symptoms were assessed at five time points during smoking cessation treatment (up to 31 days postquit). Volatility indices were calculated to quantify within-person instability of emotional symptoms over time. Over and above demographic characteristics, nicotine dependence, and abstinence status, greater baseline trait mindfulness predicted lower volatility of negative affect and depressive symptoms surrounding the quit attempt and up to 1 month postquit, ps < 0.05. Although volatility did not mediate the association between greater mindfulness and smoking cessation, these results are the first to show that mindfulness is linked to lower affective volatility (or greater stability) of negative emotions during the course of smoking cessation. The present study suggests that mindfulness is linked to greater emotional stability and augments the study of mindfulness in diverse populations. Future studies should examine the effects of mindfulness-based interventions on volatility and whether lower volatility explains effects of mindfulness-based treatments on smoking cessation.

Relations between mindfulness and mental health outcomes: need fulfillment as a mediator

Links between mindfulness and mental health outcomes have been established, but the explanatory mechanisms responsible for these associations are far less understood. This study examined relationships between mindfulness, need fulfillment and mental health outcomes (negative affect and depressive symptoms). The primary purpose of this paper was to, first, verify the link between mindfulness and mental health outcomes, and second, to better understand and explain why mindfulness is important for mental health outcomes. Specifically, this study sought to examine the potential mediating influence of need fulfillment in the relationship between mindfulness and mental health outcomes. A sample of 399 university students and employees responded to an online survey. Data were collected on personal ratings of trait mindfulness, need fulfillment, negative affect and depressive symptoms. Results indicated a significant positive relationship between mindfulness and need fulfillment, and these variables were negative...

Effects of depressive symptoms on antecedents of lapses during a smoking cessation attempt: an ecological momentary assessment study

To investigate pathways through which momentary negative affect and depressive symptoms affect risk of lapse during smoking cessation attempts. Ecological momentary assessment was carried out during 2 weeks after an unassisted smoking cessation attempt. A 3-month follow-up measured smoking frequency. Data were collected via mobile devices in German-speaking Switzerland. A total of 242 individuals (age 20-40, 67% men) reported 7112 observations. Online surveys assessed baseline depressive symptoms and nicotine dependence. Real-time data on negative affect, physical withdrawal symptoms, urge to smoke, abstinence-related self-efficacy and lapses. A two-level structural equation model suggested that on the situational level, negative affect increased the urge to smoke and decreased self-efficacy (β = 0.20; β = -0.12, respectively), but had no direct effect on lapse risk. A higher urge to smoke (β = 0.09) and lower self-efficacy (β = -0.11) were confirmed as situational antecedents of lapses. Depressive symptoms at baseline were a strong predictor of a person's average negative affect (β = 0.35, all P < 0.001). However, the baseline characteristics influenced smoking frequency 3 months later only indirectly, through influences of average states on the number of lapses during the quit attempt. Controlling for nicotine dependence, higher depressive symptoms at baseline were associated strongly with a worse longer-term outcome. Negative affect experienced during the quit attempt was the only pathway through which the baseline depressive symptoms were associated with a reduced self-efficacy and increased urges to smoke, all leading to the increased probability of lapses.

Examining mutual suppression effects in the assessment of perfectionism cognitions: evidence supporting multidimensional assessment.

Perfectionism cognitions capture automatic perfectionistic thoughts and have explained variance in psychological adjustment and maladjustment beyond trait perfectionism. The aim of the present research was to investigate whether a multidimensional assessment of perfectionism cognitions has advantages over a unidimensional assessment. To this aim, we examined in a sample of 324 university students how the Perfectionism Cognitions Inventory (PCI) and the Multidimensional Perfectionism Cognitions Inventory (MPCI) explained variance in positive affect, negative affect, and depressive symptoms when factor or subscale scores were used as predictors compared to total scores. Results showed that a multidimensional assessment (PCI factor scores, MPCI subscale scores) explained more variance than a unidimensional assessment (PCI and MPCI total scores) because, when the different dimensions were entered simultaneously as predictors, perfectionistic strivings cognitions and perfectionistic concerns cognitions acted as mutual suppressors thereby increasing each others' predictive validity. With this, the present findings provide evidence that--regardless of whether the PCI or the MPCI is used--a multidimensional assessment of perfectionism cognitions has advantages over a unidimensional assessment in explaining variance in psychological adjustment and maladjustment.

Ecological Momentary Assessment of Antecedents and Consequences of Smoking in Adults with Attention-Deficit/Hyperactivity Disorder

The current study assessed antecedents and consequences of ad lib cigarette smoking in smokers diagnosed with attention-deficit/hyperactivity disorder (ADHD) using ecological momentary assessment (EMA). Adult smokers with ADHD (n = 17) completed 870 smoking and 622 nonsmoking electronic diary entries over a 7-day observation period of their naturalistic smoking behavior. Data collection occurred from 2011 to 2012. Generalized estimating equations indicated that ADHD smokers were more likely to smoke when urge to smoke, negative affect, boredom, stress, worry, and restlessness were elevated. In addition, participants were more likely to smoke in situations that elicited higher levels of nervousness and frustration. ADHD symptoms, in general, did not differ between smoking and nonsmoking contexts, though hyperactive–impulsive ADHD symptoms were elevated prior to smoking in frustrating situations. Additional situational antecedent variables were associated with smoking, including being in the presence of others smoking, being in a bar or restaurant, while outside, and while consuming caffeinated or alcoholic beverages. Participants also reported a significant improvement in urge to smoke, negative affect, stress, hunger, and ADHD symptoms after smoking a cigarette. Findings suggest certain contextual factors that may maintain ad lib cigarette smoking in smokers with ADHD and identify potential treatment targets in smoking cessation interventions for this at-risk group. Clinical implications and future research directions are discussed. Funding for this study was provided by the National Institute on Drug Abuse.

Affective mediators of a physical activity intervention for depression in multiple sclerosis.

Previous analyses showed that a telephone-based intervention to increase physical activity in individuals with multiple sclerosis (MS) and depression resulted in significantly improved depressive symptoms compared to a wait-list control group. The aim of this study was to test positive affect and negative affect as mediators of the effect of the physical activity counseling on depressive symptoms. Ninety-two adults with MS, who met diagnostic criteria for either major depression or dysthymia and who reported low levels of physical activity, were randomized 1:1 to a 12-week telephone-based motivational interviewing (MI) intervention to improve physical activity (n = 44) or to a 12-week wait-list control group (n = 48). Self-reported positive and negative affect, physical activity, and depressive symptoms were gathered at baseline and postintervention. Path-analysis was used to test whether positive affect and negative affect mediated the positive effects of the intervention on depressive symptoms. Both positive and negative affect were significant mediators of the effects of the intervention on depressive symptoms; however, only positive affect mediated the association between changes in physical activity and improved depressive symptoms. Findings support physical activity and positive affect as key mediators of the MI treatment effect on improved mood. Decreases in negative affect were also evident in the treatment group, but were not related to improved physical activity. Findings may suggest the use of exercise-based interventions in conjunction with treatments that specifically target negative affective mechanisms for depression.